Tropical Storm Marco

Tropical Storm Marco Track 2200 Hours August 24 2020

Tropical Storm Marco Wind Speed FieldTropical Storm Marco – NWS National Hurricane Center Miami FL 1000 PM CDT Mon Aug 24, 2020 (see 10 pm video below)

Visible imagery and surface observations indicated that Marco made landfall around 6 pm CDT near the mouth of the Mississippi River. Shortly before landfall, reports from an Air Force Reserve Hurricane Hunter plane indicated that Marco was still producing a small area of tropical-storm-force winds over water to the northeast of its center. Since then, the system has moved almost due west along the southeast coast of Louisiana while its deep convection has become farther displaced from the low-level center. Between the lack of central convection and Marco’s proximity to land, it is likely that the winds have decreased since earlier this evening and the intensity has been lowered to 30 kt.

If deep convection does not redevelop overnight, Marco will become a remnant low as soon as Tuesday morning. Regardless of its status, Marco should move generally westward near the coast of Louisiana while it weakens for the next day or so and could continue to produce heavy rain for portions of the north-central Gulf Coast tonight. The system is then forecast to dissipate by early Wednesday, if not sooner.

FORECAST POSITIONS AND MAX WINDS

INIT  25/0300Z 29.0N  89.8W   30 KT  35 MPH - Depression (ESE Port Fourchon, LA)
 12H  25/1200Z 29.0N  91.3W   25 KT  30 MPH - Low (ESE Marsh Island, LA)
 24H  26/0000Z 29.0N  93.3W   25 KT  30 MPH - Low (ESE Galveston, TX)
 36H  26/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Mon Aug 24, 2020 

There has been little change to the structure of Marco over the past few hours, with the deep convection and associated heavy rainfall being sheared well to the northeast of the exposed center of circulation. Based on earlier Hurricane Hunter aircraft and scatterometer data, there was a small area of tropical-storm-force winds in the strongest convection located about 50-75 n mi offshore of the northern Gulf coast. Since the shower and thunderstorm activity is persisting, it is assumed that these winds are still occurring in that offshore area and the initial intensity is being held at 35 kt.

The exposed vortex should continue to spin down as the center of the cyclone reaches the southeastern Louisiana coast late this evening, which would result in the coastal areas being spared from experiencing sustained tropical-storm-force winds. The official NHC forecast shows Marco weakening to a tropical depression tonight, which is in agreement with the model guidance. Strong vertical wind shear should strip away any remaining convection associated with Marco at some point tonight, as indicated by GFS and ECMWF simulated satellite imagery. When the convection does diminish, most of the model guidance does not show any significant new convection developing thereafter. So it is anticipated that Marco will degenerate to a remnant low by Tuesday.

Marco’s initial motion is northwest at 6 kt. As the cyclone continues to weaken and degenerate to a remnant low, a turn to the west-northwest is expected as the system becomes steered in the low-level flow. The latest NHC track forecast is little changed from the previous one, and is near the TVCN consensus track guidance.

Key Messages:

  • 1. Gusty winds, heavy rainfall, and lingering coastal flooding are expected from Marco along portions of the Gulf Coast through this evening. For information on these hazards see products from your local National Weather Service office.
  • 2. Tropical Storm Laura could bring dangerous storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of the week, and tropical cyclone wind and surge watches have been issued for portions of the U.S. Gulf Coast.
FORECAST POSITIONS AND MAX WINDS

INIT  24/2100Z 29.0N  88.9W   35 KT  40 MPH - Tropical Storm (ESE Port Eads, Louisiana)
 12H  25/0600Z 29.7N  89.9W   30 KT  35 MPH - Depredion (ENE Carlisle, Louisiana)
 24H  25/1800Z 30.3N  91.8W   25 KT  30 MPH - Low (WSW Henderson, Louisiana)
 36H  26/0600Z 30.8N  94.0W   20 KT  25 MPH - Low (WSW Zion Hill, Texas)
 48H  26/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Mon Aug 24, 2020 

Strong southwesterly shear is taking its toll on Marco, with the edge of the nearest deep convection now displaced 50 n mi northeast of the exposed circulation center. Data from an Air Force Reserve Hurricane Hunter aircraft that investigated the system this morning measured 45-kt surface winds with the onboard SFMR instrument in that convection, but winds of only 20 to 30 kt were measured between this thunderstorm activity and the cyclone’s center. Sampling by the aircraft has also revealed that winds of tropical storm force are likely no longer occurring in any portion of the circulation except in that convection. Based on the SFMR data, the initial intensity is initialized at 45 kt.

The shear is not forecast to abate in the foreseeable future, and the simulated satellite imagery in the GFS and ECMWF suggests that Marco will degenerate into a remnant low on Tuesday. The latest NHC forecast is near the various consensus aids, which shows the cyclone weakening to a tropical depression late tonight. Based on the updated intensity forecast, tropical storm conditions are no longer expected to be produced by Marco over the central portions of the Louisiana coast, and the Tropical Storm Warnings for those locations have been discontinued.

Marco has slowed down and has moved a little to the right of the forecast track over the past few hours, with an initial motion of NNW/7 kt. The track guidance for the entire forecast period has shifted back northward, and is just south of where it was this time yesterday. The official forecast track was adjusted eastward in the near term to accommodate the recent right-of-track bias. After 12 h, the track forecast lies between the previous one and most of the consensus track guidance. On this track, Marco is expected to move inland tonight, and remain inland when the system turns west-northwestward in the low-level flow by Tuesday morning.

Key Messages:

  • 1. Gusty winds, dangerous storm surge, and heavy rainfall are expected from Marco along portions of the Gulf Coast beginning later today. Interests in these areas should follow any advice given by local government officials.
  • 2. Tropical Storm Laura could bring additional storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of the week. This could result in a prolonged period of hazardous weather for areas that may also be affected by Marco. Interests there should monitor the progress of Marco and Laura and updates to the forecast during the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  24/1500Z 28.5N  88.5W   45 KT  50 MPH - Tropical Storm (ESE Port Eads, Louisiana)
 12H  25/0000Z 29.2N  89.3W   35 KT  40 MPH - Tropical Storm (WNW Pilottown, Louisiana)
 24H  25/1200Z 30.0N  91.3W   30 KT  35 MPH - Low (WNW Pierre Part, Louisiana)
 36H  26/0000Z 30.5N  93.6W   30 KT  35 MPH - Low (WSW  Fields, Louisiana)
 48H  26/1200Z 30.9N  95.9W   25 KT  30 MPH - Low (WSW Madisonville, Texas)
 60H  27/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Sun Aug 23, 2020 

Marco is feeling the effect of strong southwesterly shear. The center, as identified by an Air Force Reserve Hurricane Hunter aircraft, is displaced to the southwest edge of the convective canopy. That said, Marco has not quite fully decoupled yet and has moved well right of the previous forecast. Data from the plane indicates that Marco has weakened; the highest flight-level winds were only 58 kt with unflagged SFMR winds just above 50 kt. Marco’s intensity has been lowered slightly to 60 kt, but this is probably generous.

The intensity guidance remains maddeningly inconsistent. The most recent runs of the HWRF and HMON show that there is still a chance that Marco could reach the Gulf Coast as a hurricane, despite the shear. While this seems unlikely given the current structure of the cyclone, it also seems slightly premature to rule it out entirely. After all, the shear lessened enough to allow Marco to briefly strengthen after it was strongly sheared for a time last night. The rest of the guidance shows Marco weakening further as it approaches the coast, and this seems like a more likely solution. The NHC forecast just holds Marco at 60 kt for the next 24 h, but its certainly possible it could already be weaker than that. Rapid weakening is likely by 36 h if it hasn’t happened sooner and Marco is forecast to become a remnant low by early Wednesday.

Marco’s track is tied entirely to its intensity and structure. Once Marco becomes fully decoupled it will slow and turn westward. It is not out of the question that this could happen before Marco reaches the coast and the system never makes landfall. However, as long as the strong southwesterly upper-level flow contributes to the steering, Marco will continue to move more northward to north-northwestward. Due to the recent northward movement of Marco’s center, the NHC track forecast has been adjusted in that direction, but it is blended to the previous forecast by about 36 h and onward. Confidence in this forecast unfortunately remains low since the model spread remains usually high.

It is worth noting that Marco is a small tropical cyclone. The large area of Tropical Storm and Hurricane watches and warnings along the northern Gulf Coast is a reflection of the unusually high uncertainty in the forecast, and it is unlikely that all of those regions will experience tropical-storm-force winds or life-threatening storm surge associated with Marco. However, impacts will likely occur in some portions of the watch/warning area beginning on Monday, and heavy rain is likely across most of the region during the next couple of days. Changes to the watches and warnings are likely on Monday and users should consult products from their local weather forecast office for more information about potential hazards in their area.

Key Messages:

  • 1. Strong winds, life-threatening storm surge, and heavy rainfall are expected from Marco along portions of the Gulf Coast beginning on Monday. Interests in these areas should follow any advice given by local government officials.
  • 2. Tropical Storm Laura could bring additional storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of the week. This could result in a prolonged period of hazardous weather for areas that may also be affected by Marco. Interests there should monitor the progress of Marco and Laura and updates to the forecast during the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  24/0300Z 26.8N  87.6W   60 KT  70 MPH - Tropical Storm (WNW Fot Myers, FL)
 12H  24/1200Z 28.0N  88.7W   60 KT  70 MPH - Tropical Storm (ESE Port Eads, LA)
 24H  25/0000Z 29.0N  90.2W   60 KT  70 MPH - Tropical Storm (WSW Port Fourchon, LA)
 36H  25/1200Z 29.6N  92.0W   40 KT  45 MPH - Tropical Storm (Marsh Island, LA)
 48H  26/0000Z 29.8N  93.6W   30 KT  35 MPH - Post Tropical (ESE Baytown, TX)
 60H  26/1200Z 29.7N  94.9W   25 KT  30 MPH - Post Tropical (ESE Baytown, TX)
 72H  27/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Sun Aug 23, 2020

Shortly after the 10 AM CDT advisory was issued, the Air Force Reserve Hurricane Hunter aircraft investigating Marco measured SFMR winds of 65 to 69 kt for several minutes. A dropsonde around the same time also measured winds equivalent to 64 kt at the surface. Based on these data, it was evident that Marco had strengthened into a hurricane. Since that time, the convective pattern has changed little, and the final leg of the aircraft mission did not reveal any notable changes to the cyclone’s intensity. Therefore, the initial intensity has been set to 65 kt, which is also in agreement with the latest Dvorak intensity estimate from SAB.

Marco continues to move north-northwest at around 11 kt. Model guidance is in good agreement on a north-northwest and then northwest motion into Monday morning as Marco nears the northern Gulf coast. However, there has been a major shift in the track guidance beyond Monday morning, and the majority of the forecast models now keep Marco offshore of the northern Gulf coast for the next few days rather than moving it inland over Louisiana Monday afternoon. Since this shift was so abrupt, I would rather split the difference between the previous official forecast track and the latest consensus tracks until another round of model runs can confirm this new suggested track is higher confidence. Based on this shift in track, tropical storm conditions are expected farther west along the Louisiana coast, and a Tropical Storm Warning has been issued from Morgan City to Cameron, Louisiana. It should be noted that if the trend in the models are correct, some of the impacts over portions of the north-central Gulf coast could be lessened.

The current shear analysis from UW-CIMSS shows that Marco is experiencing about 20-25 kt of southwesterly shear, yet Marco has been able to slowly strengthen in this environment today, likely due to the presence of very warm waters and plenty of atmospheric moisture. By late tonight and through Monday, the SHIPS guidance suggests this shear will increase to over 30 kt. This should limit any further intensification, and could cause Marco to weaken before it nears the northern Gulf coast Monday afternoon. By Monday night, the shear is forecast to increase to close to 40 kt, which should strip the convection away from the center of the cyclone, causing it to weaken. After 48 h, Marco is now expected to become a remnant low devoid of deep convection. The official NHC intensity forecast is similar to the previous one, but is at the high end of the guidance through 24 h.

Key Messages:

  • 1. Hurricane conditions, life-threatening storm surge, and heavy rainfall are expected from Marco along portions of the Gulf Coast beginning on Monday. Interests in these areas should follow any advice given by local government officials.
  • 2. Tropical Storm Laura could bring additional storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of the week. This could result in a prolonged period of hazardous weather for areas that may also be affected by Marco. Interests there should monitor the progress of Marco and Laura and updates to the forecast during the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  23/2100Z 25.8N  87.8W   65 KT  75 MPH - Category 1 (WSW Naples, FL)
 12H  24/0600Z 27.1N  88.6W   65 KT  75 MPH - Category 1 (WSW St. Petersburg, FL)
 24H  24/1800Z 28.5N  89.7W   65 KT  75 MPH - Category 1 (WSW Port Eads, LA)
 36H  25/0600Z 29.3N  91.4W   50 KT  60 MPH - Tropical Storm (ESE Bayou Vista, LA)
 48H  25/1800Z 29.8N  93.2W   35 KT  40 MPH - Tropical Storm (WNW Creole, LA)
 60H  26/0600Z 29.9N  95.1W   30 KT  35 MPH - Low (WSW Crosby, TX)
 72H  26/1800Z 29.7N  96.8W   25 KT  30 MPH - Low (Weimar, TX)
 96H  27/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Sun Aug 23, 2020

Deep convection with cloud tops of -75 to -80 degrees C has persisted over the center of Marco for the past several hours. An Air Force Reserve Hurricane Hunter aircraft currently investigating the cyclone measured winds equivalent to 62 kt both with the SFMR and in a dropsonde in the northeastern eyewall. However, the aircraft reported peak 850-mb flight level winds of only 64 kt. Based on a blend of these data it appears that Marco is on the cusp of becoming a hurricane, but is not quite there yet. Therefore, the initial intensity remains 60 kt.

Based on the SHIPS guidance, Marco has about a 12-24 hour window to intensify in an environment characterized by moderate southwesterly shear, very warm waters, and plenty of atmospheric moisture. After that time, the vertical wind shear is expected to increase and this should begin to dominate the cyclone’s environment. The latest NHC intensity forecast is unchanged from the previous one, forecasting Marco to become a hurricane later today, and maintaining hurricane intensity up until landfall in agreement with the latest LGEM intensity guidance. While it is possible that Marco will weaken just prior to landfall due to the increasing shear, there is little difference in the impacts between a 60 and 65 kt system.

Marco is moving north-northwestward or 340/12 kt. Although the overall guidance has not changed much since the previous advisory, there remains considerable spread in this guidance by the time Marco reaches the northern Gulf coast. This spread could be attributed to the varying ways the models handle the system as it encounters the more hostile environment near the coast. Since the track consensus aids have changed little through 36 h, the official forecast is essentially the same as the previous one through that time. The model guidance has shifted a little northward beyond 36 h, so the official forecast was nudged to the north during that time as well.

Key Messages:

  • 1. Hurricane conditions, life-threatening storm surge, and heavy rainfall are expected from Marco along portions of the Gulf Coast beginning on Monday, and Hurricane and Storm Surge Warnings have been issued. Interests in these areas should follow any advice given by local government officials.
  • 2. Tropical Storm Laura could bring additional storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of the week. This could result in a prolonged period of hazardous weather for areas that may also be affected by Marco. Interests there should monitor the progress of Marco and Laura and updates to the forecast during the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 24.7N  87.3W   60 KT  70 MPH - Tropical Storm (WSW Key West, FL)
 12H  24/0000Z 26.4N  88.1W   65 KT  75 MPH - Category 1 (WSW Fort Myers, FL)
 24H  24/1200Z 28.2N  89.1W   65 KT  75 MPH - Category 1 (WSW Port Eads, LA)
 36H  25/0000Z 29.5N  90.4W   55 KT  65 MPH - Tropical Storm (WSW Cut Off, LA)
 48H  25/1200Z 30.5N  92.1W   35 KT  40 MPH - Tropical Storm (WSW Opelousas, LA)
 60H  26/0000Z 31.2N  93.8W   30 KT  35 MPH - Low (WNW  Fairmount, TX)
 72H  26/1200Z 31.8N  95.4W   25 KT  30 MPH - Low (WNW Maydelle, TX)
 96H  27/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Sat Aug 22, 2020 

Marco has taken on distinctly sheared appearance. Reports from an Air Force Reserve Hurricane Hunter plane, microwave imagery, and radar imagery from Cuba all indicate that deep convection is limited to the east side of the tropical storm and that it no longer has a nearly closed eyewall. The degradation of Marco’s structure appears to be primarily due to strong upper-level southwesterly flow. Despite the shear, the plane still measured SFMR winds near 55 kt and the intensity is held at that value.

Marco is a small tropical storm and will be susceptible to rapid changes in structure and intensity until it reaches the northern Gulf Coast. Such systems are often not very resilient in a high-shear environment, however even a brief relaxation of the shear could result in quick strengthening. It would not be surprising if Marco’s intensity evolves in step-wise fashion consisting of periods of arrested development followed by fast strengthening if/when the shear relaxes. While the statistical models still show Marco becoming a hurricane within 24 h, the run-to-run consistency of the dynamical guidance remains poor. The latest HWRF, HMON and GFS forecasts show Marco weakening as it approaches the northern Gulf Coast, and this remains a distinct possibility if the shear remains consistently high. The NHC intensity forecast has not been changed substantially, in large part due to the low confidence of the forecast, and is consequently above all of the guidance at 36 and 48 h when Marco is forecast to be near the northern Gulf Coast. Additional adjustments to the forecast are likely on Sunday.

In sharp contrast to earlier today, no large changes were made to the track forecast, though that should not be interpreted as an increase in forecast confidence. Marco is forecast to move north-northwestward and approach the northern Gulf Coast on Monday. As it moves inland and weakens, a turn toward the west at a slower forward speed is anticipated. This turn could occur before or after Marco moves inland, and will be tied in part to exactly when Marco begins to weaken since a stronger, deeper storm should continue to feel the affects of the upper-level southwesterly flow and move farther north while a weaker system will be steered westward by a low- to mid-level ridge extending over the southeastern US. The NHC forecast is nearly on top of the multi-model consensus, but the spread in the guidance is still higher than normal.

Key Messages:

  • 1. Tropical storm conditions will continue over portions of extreme western Cuba for a few more hours. Heavy rainfall is also expected overnight in the eastern portions of the Mexican states of Quintana Roo and Yucatan, and across far western Cuba, which could result in flash flooding.
  • 2. Marco is expected to be at or near hurricane strength when it approaches the central Gulf Coast as a hurricane on Monday. Hurricane conditions, life-threatening storm surge, and heavy rainfall are possible along portions of the Gulf Coast beginning on Monday, and Hurricane and Storm Surge watches have been issued. Interests in these areas should follow any advice given by local government officials.
  • 3. Tropical Storm Laura could bring additional storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of next week. This could result in a prolonged period of hazardous weather for areas that may also be affected by Marco. Interests there should monitor the progress of Marco and Laura and updates to the forecast during the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  23/0300Z 22.8N  86.3W   55 KT  65 MPH - Tropical Storm (WNW Cancun, Mexico)
 12H  23/1200Z 24.3N  87.1W   65 KT  75 MPH - Category 1 (WNW Cancun, Mexico)
 24H  24/0000Z 26.3N  87.9W   70 KT  80 MPH - Category 1 (WSW Fort Myers, FL)
 36H  24/1200Z 28.3N  88.9W   70 KT  80 MPH - Category 1 (ESE Port Eads, LA)
 48H  25/0000Z 29.6N  90.4W   55 KT  65 MPH - Tropical Storm (WNW Larose, LA)
 60H  25/1200Z 30.5N  92.0W   35 KT  40 MPH - Tropical Storm (WNW  Leonville, LA)
 72H  26/0000Z 30.9N  93.5W   30 KT  35 MPH - Depression (ESE  Almadane, LA)
 96H  27/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Sat Aug 22, 2020

Cutting to the chase, there have been some big changes among the model guidance, and subsequently the NHC forecast, for Marco this afternoon. While at this point it’s a little speculative, the data collected by this morning’s NOAA G-IV flight in the environment around Marco and across the Gulf of Mexico may have played a key role in the significant eastward shift seen in nearly all the 12z models. This isn’t to say that the uncertainty in the eventual track has diminished.

In fact, various ensemble members from some of the global models still show a potential risk to the coast anywhere from Texas to Alabama, and it’s entirely possible that the volatile shifts seen in the models could continue. That being said, the new NHC track forecast has been shifted significantly eastward and now shows the center of Marco reaching southeastern Louisiana in about 2 days, which is the scenario currently shown by the GFS, ECMWF, HCCA, Florida State Superensemble, and the TVCN multi-model consensus. After Marco reaches the coast, the western Atlantic ridge is expected to build westward and should cause the cyclone to move more slowly toward the west-northwest across southern portions of Louisiana.

As far as the intensity is concerned, the last fix made by this morning’s reconnaissance flight indicated that the pressure had leveled off, and no higher winds had been observed from what was measured earlier in the flight. The radar presentation from Cuban radar has also degraded a bit, so Marco’s initial intensity is held at 55 kt. Marco is beginning to move into a zone of moderate southwesterly shear, but otherwise favorable conditions of warm ocean water and some upper-level divergence are expected to foster strengthening during the next day or so. With the exception of the HWRF, the other intensity models show Marco reaching hurricane strength, and the NHC foreast continues to show that possibility while Marco moves over the central Gulf. The shear is still expected to strengthen in 36-48 hours when the system is approaching the northern Gulf Coast, but with the shift in the forecast track, now there may not be enough time for Marco to weaken below hurricane intensity before it reaches land. The new NHC intensity forecast is near or just above the HCCA and Florida State Superensemble models and holds Marco as a hurricane until it reaches the coast.

The forecast track changes now bring tropical storm force winds to the coast in 36-48 hours, which necessitates the issuance of Hurricane and Storm Surge Watches for a portion of the northern Gulf Coast. These watches will likely need to be upgraded to warnings later tonight.

Key Messages:

  • 1. Tropical storm conditions will continue over portions of extreme western Cuba through this evening. Heavy rainfall is also expected in the eastern portions of the Mexican states of Quintana Roo and Yucatan, and across far western Cuba, which could result in flash flooding.
  • 2. Marco is expected to approach the central Gulf Coast as a hurricane on Monday. Hurricane conditions, life-threatening storm surge, and heavy rainfall are possible along portions of the Gulf Coast beginning on Monday, and Hurricane and Storm Surge watches have been issued. Interests in these areas should follow any advice given by local government officials.
  • 3. Tropical Storm Laura could bring additional storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of next week. This could result in a prolonged period of hazardous weather for areas that could be affected by Marco. Interests there should monitor the progress of Marco and Laura and updates to the forecast during the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  22/2100Z 21.9N  85.7W   55 KT  65 MPH - Tropical Storm (WNE Las Tubas, Cuba)
 12H  23/0600Z 23.3N  86.5W   65 KT  75 MPH - Category 1 (WNE Las Tubas, Cuba)
 24H  23/1800Z 25.3N  87.3W   75 KT  85 MPH - Category 1 (WSW Naples, FL)
 36H  24/0600Z 27.5N  88.3W   75 KT  85 MPH - Category 1 (ESE New Orleans, LA)
 48H  24/1800Z 29.3N  89.6W   65 KT  75 MPH - Category 1 (WSW Empire, LA)
 60H  25/0600Z 30.4N  91.1W   50 KT  60 MPH - Tropical Storm (ESE Baton Rouge, LA)
 72H  25/1800Z 31.1N  92.7W   40 KT  45 MPH - Tropical Storm (ENE Calcasieu, LA)
 96H  26/1800Z 32.3N  95.6W   25 KT  30 MPH - Low (ESE Brownsboro, TX )
120H  27/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Sat Aug 22, 2020 

Reconnaissance data, geostationary and microwave satellite imagery, and radar data from Cuba all indicate that Marco is strengthening quickly this morning. The Air Force Reserve Hurricane Hunters measured a peak 850-mb flight-level wind of 69 kt, and there were several SFMR measurements of 50-55 kt to the northeast of the center. These data support raising Marco’s initial intensity to 55 kt, and the central pressure based on dropsonde data has fallen to 992 mb. The crew on the plane reported the formation of a partial eyewall, which agrees with what we’ve seen on recent microwave and radar images.

The track forecast has been complicated by the fact that the plane has fixed Marco’s center to the east of the previous forecast track, and that makes the current motion north-northwestward, or 340/10 kt. The subtropical ridge currently located over the southwestern Atlantic is forecast to build westward along the northern Gulf Coast during the next few days, and this expanding ridge is expected to push Marco northwestward and then eventually westward while the cyclone moves across the Gulf of Mexico. This general thinking has not changed, but the adjusted initial position ended up shifting the track guidance to the north and east on this cycle. In response, the new NHC track forecast has been adjusted eastward and northward during the first 3 days and is generally between the HCCA and TVCN consensus aids.

Marco has finally tapped into the favorable conditions over the northwestern Caribbean Sea, and the cyclone’s overall small size and small radius of maximum winds makes it susceptible to quick changes in intensity. The tropical storm is just beginning to move into a higher zone of shear to its north, but conditions should remain conducive enough for Marco to intensity to a hurricane during the next 24 hours. After that time, southwesterly shear is expected to increase over 20 kt by day 2 and then over 30 kt by day 3, and those conditions, along with the cyclone’s small size, should cause weakening as Marco gets closer to the central and northwestern Gulf coast. The updated NHC intensity forecast has been increased during the first 2 days and lies above the HCCA/Florida State Superensemble solutions but below the SHIPS/LGEM scenarios. The intensity forecast comes back in line with the previous forecast by day 3 during the expected weakening phase, and Marco is ultimately expected to dissipate over Texas by the end of the forecast period.

The updated track forecast suggests that watches could be required for a portion of the central Gulf Coast later today.

Key Messages:

  • 1. Marco is forecast to strengthen to a hurricane as it moves into the southeastern Gulf of Mexico by tonight, and tropical storm conditions are expected over the northeastern coast of the Yucatan Peninsula and in extreme western Cuba. Heavy rainfall is also expected in the eastern portions of the Mexican states of Quintana Roo and Yucatan, and across far western Cuba, which could result in flash flooding.
  • 2. Marco is expected to move across the central Gulf of Mexico as a hurricane Sunday and approach the central Gulf Coast on Monday. There is an increasing risk of impacts from storm surge, winds, and heavy rainfall from the upper Texas coast to Louisiana early next week, and interests there should monitor the progress of Marco, as storm surge, tropical storm, and/or hurricane watches could be issued later today.
FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 20.9N  85.3W   55 KT  65 MPH - Tropical Storm (ENE Play del Carmen, Mexico)
 12H  23/0000Z 22.1N  86.0W   65 KT  75 MPH - Category 1 (WSW Las Tumbas, Cuba)
 24H  23/1200Z 23.9N  87.1W   75 KT  85 MPH - Category 1 (WNW Cancun, Mexico)
 36H  24/0000Z 25.6N  88.4W   75 KT  85 MPH - Category 1 (WSW Naples, FL)
 48H  24/1200Z 27.2N  89.9W   70 KT  80 MPH - Category 1 (WSW Port Eads, LA)
 60H  25/0000Z 28.5N  91.6W   60 KT  70 MPH - Tropical Storm (WSW Grand Isle, LA)
 72H  25/1200Z 29.1N  93.6W   50 KT  60 MPH - Tropical Storm (WSW Galveston, TX)
 96H  26/1200Z 29.3N  96.6W   35 KT  40 MPH - Tropical Storm (WSW  Speaks, TX)
120H  27/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM EDT Fri Aug 21, 2020 

An Air Force Reserve Hurricane Hunter aircraft has investigated the system over the northwest Caribbean during the past few hours. The plane reported a number of unflagged SFMR winds between 35 and 40 kt and max flight level winds of 41 kt. A blend of these data supports an intensity of 35 kt, and therefore, this system has been designated as Tropical Storm Marco. Deep convection has increased near and to the east of Marco’s center during the past few hours. Although there still isn’t much evidence of inner-core banding, the data from the plane does indicate that the center of Marco has become better defined since the afternoon and that the minimum pressure has dropped.

Unfortunately the intensity forecast has not become any clearer and confidence in that aspect of the forecast is quite low. Marco is embedded within an environment that could support a fast rate of strengthening. However, recent microwave data does not indicate that the system has developed an inner-core, and only gradual strengthening is likely until it does. The intensity guidance spread is quite high, with the GFS and ECMWF global models both showing little further strengthening, while the HMON regional model rapidly makes Marco a hurricane before it reaches the northeast tip of the Yucatan peninsula. That possibility can not be ruled out, but a majority of the intensity guidance favors the weaker solution of the global models. Even with the HMON outlier included, the NHC intensity forecast is above the model consensus. Once Marco moves over the central Gulf of Mexico, a rapid increase in wind shear associated with an upper-level trough should limit the potential for further strengthening, and weakening is still anticipated before Marco nears the northern Gulf Coast, as shown in the previous official forecast.

Confidence in the track forecast is also lower than normal, as the models spread remains quite high. Only small adjustments were made to the NHC forecast which heavily favors the GFS and ECMWF solutions on the left side of the track guidance. It is worth noting that the NHC track forecast is near middle of the GFS and ECMWF ensembles. Marco is currently forecast to move northwestward toward a weakness in the subtropical ridge over the central Gulf of Mexico for the next day or two, before the ridge builds and turns the tropical cyclone farther west. Near the end of the period, Marco’s track and intensity could be also influenced by Tropical Storm Laura which is also forecast to be over the Gulf of Mexico, however the details of that interaction are highly uncertain at this time. Given the high uncertainty in the forecast, larger than normal changes could be required to future advisories.

Key Messages:

  • 1. Marco is forecast to strengthen over the northwestern Caribbean Sea through Saturday as it approaches the northeast coast of the Yucatan Peninsula. A Hurricane Watch and a Tropical Storm Warning are in effect for portions of that region.
  • 2. The system is expected to move into the south-central Gulf of Mexico as a tropical storm on Sunday. Although some strengthening is anticipated on Sunday, weakening is forecast as the system approaches the northwestern Gulf coast on Tuesday. It is still too soon to know exactly the location and magnitude of impacts the system will produce along the central or northwestern Gulf Coast, and interests in that area should continue monitoring the progress of this system over the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  22/0300Z 18.7N  84.9W   35 KT  40 MPH - Tropical Storm (ESE Mahahual, Mexico)
 12H  22/1200Z 19.7N  85.7W   45 KT  50 MPH - Tropical Storm (WSW Tulum, Mexico)
 24H  23/0000Z 21.1N  86.7W   50 KT  60 MPH - Tropical Storm (WNW Cancun, Mexico)
 36H  23/1200Z 22.7N  88.0W   55 KT  65 MPH - Tropical Storm (WSW Cancun, Mexico)
 48H  24/0000Z 24.4N  89.5W   60 KT  70 MPH - Tropical Storm (WNW Mérida, Mexico)
 60H  24/1200Z 25.9N  91.0W   60 KT  70 MPH - Tropical Storm (ESE Galveston, Texas)
 72H  25/0000Z 27.5N  92.8W   60 KT  70 MPH - Tropical Storm (WSW Galveston, Texas)
 96H  26/0000Z 29.0N  95.4W   45 KT  50 MPH - Tropical Storm (ESE Lake Jackson, Texas)
120H  27/0000Z 30.0N  97.4W   30 KT  35 MPH - Tropical Storm (WNW Watterson, Texas)

NWS National Hurricane Center Miami FL 500 PM EDT Fri Aug 21, 2020 

Since this morning’s advisory, the low-level swirl on which the Air Force reconnaissance plane made its last fix has apparently become the new center of circulation of the depression. A little bit of deep convection has developed over this new center during the past few hours, but on the whole there is very little convective activity in the central region of the circulation. The strongest and most persistent convection is located within a band that extends across the Cayman Islands toward western Cuba. An ASCAT pass from this morning showed winds of 25-30 kt to the northeast of the new center, so 30 kt remains the initial intensity on this advisory.

It is a bit of a mystery why the depression has struggled to develop much central convection, given a seemingly low-shear environment and warm waters. Since these conditions are expected to continue for the next few days, intensification is still indicated in the official forecast, although the rate of strengthening has been muted a bit while the system approaches the Yucatan Peninsula given its current structure. After the center moves over the Gulf of Mexico, many of the models still show the cyclone reaching hurricane intensity in about 3 days, including the intensity consensus, and that possibility is still shown in the NHC forecast. By day 4, the cyclone is likely to be blasted by 30-40 kt of southwesterly shear, which would lead to weakening while it approaches the northwestern Gulf coast. The official forecast has been reduced at that time, although it’s noteworthy to mention that it still lies above all the guidance on day 4.

Now that there is more confidence in the initial position, the new motion estimate is a little to the right from before, but still toward the northwest, or 325/11 kt. A deep-layer trough over the Gulf of Mexico is forecast to be shoved aside by the Atlantic subtropical ridge building westward over the next 2 days. Even with this pattern change, the cyclone is expected to move generally northwestward for the entire 5-day forecast period. However, there has been a notable westward bend in some of the track models, (particularly the GFS and ECMWF) from days 3-5, which is likely due those models having a weaker cyclone steered more by the low-level ridge at that time. Since the NHC intensity forecast is mirroring this particular model trend, the track forecast has been shifted westward from the previous prediction on days 4 and 5 toward the GFS and ECMWF solutions. The track forecast is still of rather low confidence, with the spread among the model guidance being larger than normal at every forecast time period.

Key Messages:

  • 1. Tropical Depression Fourteen is expected to strengthen over the northwestern Caribbean Sea through Saturday, and it could still be near hurricane strength when it reaches the east coast of the Yucatan Peninsula of Mexico late Saturday. A Hurricane Watch and a Tropical Storm Warning are in effect for portions of that region.
  • 2. The system is expected to move into the south-central Gulf of Mexico as a tropical storm on Sunday. Although some strengthening is anticipated Sunday and Monday, weakening is forecast as the system approaches the northwestern Gulf coast on Tuesday. It is still too soon to know exactly the location and magnitude of impacts the system will produce along the central or northwestern Gulf Coast, and interests in that area should continue monitoring the progress of this system over the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z 17.7N  84.3W   30 KT  35 MPH - Depression (ENE Belize City, Belize)
 12H  22/0600Z 18.6N  85.0W   35 KT  40 MPH - Tropical Storm (ESE Mahahual, MX)
 24H  22/1800Z 19.8N  85.9W   45 KT  50 MPH - Tropical Storm (ESE Cozumel, MX)
 36H  23/0600Z 21.2N  87.1W   55 KT  65 MPH - Tropical Storm (WNW Cancun, MX)
 48H  23/1800Z 22.9N  88.7W   55 KT  65 MPH - Tropical Storm (ENE Progreso, MX )
 60H  24/0600Z 24.6N  90.4W   60 KT  70 MPH - Tropical Storm (ENE Progreso, MX)
 72H  24/1800Z 26.2N  92.2W   65 KT  75 MPH - Category 1 (ENE Brownsville, TX)
 96H  25/1800Z 28.5N  95.0W   50 KT  60 MPH - Tropical Storm (ESE Galveston, TX)
120H  26/1800Z 30.0N  97.5W   30 KT  35 MPH - Low (WNW Rockne, TX)

NWS National Hurricane Center Miami FL 1100 AM EDT Fri Aug 21, 2020 

An Air Force Reserve Hurricane Hunter aircraft flew into the depression a few hours ago, and the plane made two center fixes that were about 35 n mi apart, indicating that there are likely multiple low-level swirls rotating around a common center. A well-defined swirl coincident with the second center fix has become apparent in visible satellite imagery, but for now a blend of the aircraft fixes is being used for the initial position until we can be sure the satellite feature is in fact the one and only center. Flight-level and SFMR winds, outside of heavy rainfall, indicate that the maximum winds remain 30 kt. Deep convection is still lacking in organization, with the heaviest activity well to the north near the Cayman Islands and along the Honduras coast.

The depression is moving northwestward, or 305/12 kt, along the southwestern periphery of an Atlantic subtropical ridge and toward a deep-layer trough over the Gulf of Mexico. This northwestward motion is expected to persist for the entire 5-day forecast period, with a decrease in forward speed anticipated while the cyclone approaches the Yucatan coast. The track guidance has slowed down a bit during that time, especially the GFS, and the new NHC forecast is therefore a little slower than the previous forecast. After that time, an increase in forward speed is expected, and the NHC forecast lies to the west of the TVCN model consensus, closer to the GFS, ECMWF, and HCCA scenarios.

The structure of the depression aside, the environment still appears conducive for strengthening while the system approaches the Yucatan Peninsula. Vertical shear over the depression is currently less than 10 kt and is expected to remain low for the next 36-48 hours, and sea surface temperatures will be around 30 degrees Celsius. Therefore, steady intensification is shown in the official forecast through 36 hours, and the NHC prediction lies near the upper end of the guidance envelope between the HCCA and HWRF solutions just before the center reaches the Yucatan coast.

After some weakening while over the Yucatan Peninsula, re-intensification is likely to occur over the central Gulf of Mexico between days 2 and 3 while vertical shear remains relatively low, and the cyclone could become a hurricane during that time, as shown by the HCCA, HWRF, and HMON models. After day 3, southwesterly vertical shear of 30 kt or more is expected to develop over the northwestern Gulf, and the official forecast follows the trend of all the intensity guidance, showing weakening by day 4 as the cyclone approaches the southeastern Texas or southwestern Louisiana coastline. This forecast remains highly uncertain, however, and users are urged to continue monitoring changes to this forecast over the next couple of days.

Key Messages:

  • 1. Heavy rainfall and gusty winds over portions of the coasts of Nicaragua and Honduras, including the Bay Islands, are expected to diminish today.
  • 2. Tropical Depression Fourteen is expected to strengthen over the northwestern Caribbean Sea through Saturday, and it is expected to be near or at hurricane strength when it reaches the east coast of the Yucatan Peninsula of Mexico late Saturday. A Hurricane Watch and a Tropical Storm Warning are in effect for portions of that region.
  • 3. The system is expected to move into the south-central Gulf of Mexico as a tropical storm on Sunday. Some strengthening is anticipated while it moves northwestward over the central Gulf of Mexico early next week, but it is too soon to know exactly how strong it will get or the location and magnitude of impacts it will produce along the central or northwestern Gulf Coast. Interests in that area should continue monitoring the progress of this system over the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 16.6N  84.1W   30 KT  35 MPH - Depression (WSW Barra Patuca, Honduras)
 12H  22/0000Z 17.4N  85.0W   40 KT  45 MPH - Tropical Storm (ENE Mangrove Bight, Honduras)
 24H  22/1200Z 18.6N  85.9W   50 KT  60 MPH - Tropical Storm (ESE Mahahual, Mexico)
 36H  23/0000Z 20.0N  86.9W   60 KT  70 MPH - Tropical Storm (ESE Cozumel, Mexico)
 48H  23/1200Z 21.5N  88.2W   50 KT  60 MPH - Tropical Storm (WSW Nichili, Mexico)
 60H  24/0000Z 23.2N  89.7W   55 KT  65 MPH - Tropical Storm (WNW Progreso, Mexico)
 72H  24/1200Z 25.1N  91.4W   65 KT  75 MPH - Category 1 (WSW Brownsville, TX)
 96H  25/1200Z 28.7N  94.1W   60 KT  70 MPH - Tropical Storm (WSW Galveston, TX)
120H  26/1200Z 31.3N  95.5W   40 KT  45 MPH - Tropical Storm (WSW Croskett, TX)

NWS National Hurricane Center Miami FL 1100 PM EDT Thu Aug 20, 2020

The overall convective pattern has improved somewhat since the previous advisory, with a band of deep convection having developed near and just south of the low-level center. A pronounced mid-level circulation has been rotating westward to the north of the center of the broader low-level circulation, which has likely prevented the cyclone from becoming a tropical storm by now, especially given the very impressive outflow pattern. However, NOAA buoy 42057 to the north of the center recently reported a sustained wind of 29 kt at 4 meters elevation, which equals about a 32-kt 10-meter wind speed, which means that the cyclone isn’t far from becoming a tropical storm. The intensity is being maintained at 30 kt until convection becomes more persistent.

The center has been reforming a little farther north and has also slowed down, with the initial motion now being west-northwestward or 285/12 kt. The slower and farther north initial position has required a slight northward shift in the forecast track for the next 24 hours and, as a result, the center of the cyclone is no longer expected to make landfall very far inland over Honduras or Nicaragua, if it makes landfall at all. By 36 hours, the new NHC forecast track shifts back closer to the previous advisory track due to a strong mid-level ridge extending westward across Florida and into the eastern and central Gulf of Mexico. That feature is expected to keep the cyclone moving in a general northwestward direction on days 2-5, resulting in landfall over the northeastern Yucatan Peninsula on Saturday, and be approaching the northwestern Gulf coast by the middle of next week. The official forecast track lies along the southern edge of the guidance envelope, close to the middle of the simple consensus models and a little south of the NOAA-HCCA corrected model.

Due to the northward shift in the new forecast track, the center and inner-core wind field of the cyclone will not be disrupted as much as previously expected, which has significant implications in the intensity forecast. The depression is now expected to reach hurricane strength just before it makes landfall on the east side of the Yucatan Peninsula in about 48 hours. Weakening is forecast in 60 hours while the cyclone moves across northeastern Yucatan, followed by gradual re-strengthening thereafter. Ocean temperatures along the path of the cyclone are forecast to be 30.0-30.5 deg C and the vertical shear is expected to remain low at less than 10 kt through 96 hours. Those conditions coupled with the impressive outflow pattern should allow for at least typical strengthening.

By 120 hours, the GFS- and ECMWF-based SHIPS models show the vertical wind shear increasing sharply from the southwest to 20-25 kt, which would normally induce weakening. However, it appears that those models are incorporating some strong jetstream winds of 60-70 kt well to the northwest of the center of the cyclone, which has resulted in high bias in the shear output. Therefore, the cyclone is forecast to be near hurricane strength when it approaches the Texas coast in 120 hours. The new intensity forecast is similar to but a little higher then the previous advisory due to less land interaction than previously expected, and is is a blend of the Decay-SHIPS and LGEM models, which are at the upper-end of the guidance envelope.

Key Messages:

  • 1. Tropical Depression Fourteen is expected to strengthen over the northwestern Caribbean Sea through Saturday, and is likely to produce tropical-storm-force winds and heavy rainfall over portions of the coasts of Nicaragua and Honduras, including the Bay Islands, beginning tonight through Friday. The system is expected be near or at hurricane strength when it reaches the Yucatan Peninsula of Mexico late Saturday where a Hurricane Watch and a Tropical Storm Warning are in effect.
  • 2. The system is expected to move into the south-central Gulf of Mexico as a tropical storm on Sunday. Some strengthening is anticipated while it moves northwestward over the western Gulf of Mexico early next week, but it is too soon to know exactly how strong it will get or the location and magnitude of impacts it will produce along the central or northwestern Gulf Coast. Interests in that area should continue monitoring the progress of this system over the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  21/0300Z 14.9N  82.2W   30 KT  35 MPH - Depression (ESE Bismuna Tara, Nicaragua)
 12H  21/1200Z 15.5N  83.8W   35 KT  40 MPH - Tropical Storm (ESE Uhi, Honduras)
 24H  22/0000Z 16.8N  85.1W   45 KT  50 MPH - Tropical Storm (ENE Mangrove Bight, Honduras)
 36H  22/1200Z 18.2N  86.0W   55 KT  65 MPH - Tropical Storm (ESE Xcalak, Mexico)
 48H  23/0000Z 19.8N  87.2W   65 KT  75 MPH - Category 1 (ESE Punta Allen, Mexico)
 60H  23/1200Z 21.4N  88.5W   40 KT  45 MPH - Tropical Storm (ESE  Yalsihón, Mexico)
 72H  24/0000Z 23.2N  89.8W   50 KT  60 MPH - Tropical Storm (WNW Mérida, Mexico)
 96H  25/0000Z 26.7N  92.3W   65 KT  75 MPH - Category 1 (ESE Corpus Christi, Texas)
120H  26/0000Z 29.1N  94.3W   65 KT  75 MPH - Category 1 (ESE Galveston, Texas)

NWS National Hurricane Center Miami FL 500 PM EDT Thu Aug 20, 2020

An Air Force Reserve Hurricane Hunter aircraft investigating the system found an area of lighter winds–likely where the center would be–farther south than previous estimates. The highest flight-level wind measured by the aircraft was 30 kt at an altitude of 2500 feet, and although there were some SFMR measurements over 40 kt, these looked coincident with some heavy rain rates and thus are probably not reliable. Therefore, the initial intensity remains 30 kt. Structurally, the depression has a large cloud envelope with sporadic convective cells located in loose bands.

The updated initial position derived from the aircraft data indicates that the current motion is still westward, or 270/16 kt. This southward adjustment really only affected the first 36 hours or so of the forecast, with NHC’s official track forecast being shifted southward during that period. This ends up taking the cyclone’s center over extreme northern Nicaragua and northeastern Honduras in 12-24 hours. After 36 hours, model guidance remains in good agreement that the system should turn northwestward due to a deep-layer trough over the Gulf of Mexico. The new set of model guidance has not shifted much from the previous cycle, and the NHC track forecast is very close to the morning forecast despite the initial position adjustment, with perhaps a slight eastward shift on days 4 and 5. In general, the NHC forecast is closest to the GFS and HCCA model solutions.

The depression’s farther-south position makes the intensity forecast more complicated with potentially more land interaction with parts of Central America. Slight strengthening to tropical storm strength is expected before the center reaches Honduras and Nicaragua, with little change thereafter until the center re-emerges over the Gulf of Honduras. Low shear and warm sea surface temperatures should then support further intensification up until it reaches the Yucatan Peninsula. Since there is significant uncertainty in how land interaction will affect the cyclone’s intensity, the forecast intensity has been flat-lined between day 2 and day 4, with the understanding that the the winds could increase or decrease from the value shown. Vertical shear is expected to increase by day 5, and some weakening is shown at that time.

Key Messages:

  • 1. Tropical Depression Fourteen is expected to strengthen over the northwestern Caribbean Sea through Saturday, and is likely to produce tropical-storm-force winds and heavy rainfall over portions of the coasts of Nicaragua and Honduras, including the Bay Islands, beginning tonight through Friday. The system could be near or at hurricane strength when it reaches the Yucatan Peninsula of Mexico late Saturday, and watches could be required for a portion of that area tonight.
  • 2. The system is expected to move into the south-central Gulf of Mexico as a tropical storm on Sunday. Some strengthening is anticipated while it moves northwestward over the western Gulf of Mexico early next week, but it is too soon to know exactly how strong it will get or the location and magnitude of impacts it will produce along the central or northwestern Gulf Coast. Interests in that area should continue monitoring the progress of this system over the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 14.3N  81.0W   30 KT  35 MPH - Depression [island](Fresh Water Bay, Colombia)
 12H  21/0600Z 14.7N  83.0W   35 KT  40 MPH - Tropical Storm (Bismuna Tara, Nicaragua)
 24H  21/1800Z 15.6N  84.7W   35 KT  40 MPH - Tropical Storm (WSW Brus Laguna, Honduras)
 36H  22/0600Z 17.0N  85.6W   45 KT  50 MPH - Tropical Storm (ENE Mangrove Bight, Honduras)
 48H  22/1800Z 18.7N  86.6W   55 KT  65 MPH - Tropical Storm (E Mahahual, Mexico)
 60H  23/0600Z 20.3N  87.9W   55 KT  65 MPH - Tropical Storm (WNW Tulum, Mexico)
 72H  23/1800Z 22.1N  89.2W   55 KT  65 MPH - Tropical Storm (ENE Progreso, Mexico)
 96H  24/1800Z 26.0N  91.5W   55 KT  65 MPH - Tropical Storm (ENE Brownsville, Texas)
120H  25/1800Z 28.5N  93.5W   50 KT  60 MPH - Tropical Storm (ESE Gaalveston, Texas)

NWS National Hurricane Center Miami FL 1100 AM EDT Thu Aug 20, 2020

Visible satellite images indicate that the area of disturbed weather moving across the central Caribbean Sea has developed a closed surface circulation, with the center embedded beneath cellular convective cells and a large cirrus canopy. Also, convection has increased in organization, and TAFB and SAB have given the system classification of T2.0/30 kt and T1.5/25 kt, respectively. Therefore, advisories are being initiated on Tropical Depression Fourteen with maximum winds of 30 kt. An expected ASCAT pass later today and an Air Force Reserve Hurricane Hunter mission scheduled for this afternoon should give us a better handle on both the depression’s center location and its maximum winds.

The depression continues to move westward at a pretty good clip, currently estimated to be on a heading of 280 degrees at 18 kt. This motion is being driven by the western extent of the Bermuda high, which currently noses into the northwestern Caribbean Sea. However, a deep-layer trough over the Gulf of Mexico is expected to become the main driver in the coming days, causing the cyclone to slow down and turn rather suddenly toward the west-northwest and northwest in the next 24-36 hours. A general northwestward motion should then continue until the end of the 5-day forecast period, bringing the system across the Yucatan Peninsula Saturday night and into the central and western Gulf of Mexico early next week. Most of the reliable track models are clustered close to one another, and the official NHC track forecast is therefore very close to the multi-model consensus aids, including the HCCA model.

Once the depression slows down during the next 24-36 hours, environmental conditions appear ideal for strengthening. The magnitude of vertical shear is expected to be less than 10 kt for at least the next 2 days, while the system will be moving over the deep, warm waters of the northwestern Caribbean Sea, where sea surface temperatures are 29-30 degrees Celsius. Given these conditions, some of the intensity guidance actually appears more muted than I would have expected, and I have therefore elected to closely follow the SHIPS and LGEM models, which are near the upper end of the guidance envelope.

It is possible that the depression could be near or at hurricane strength when it approaches the Yucatan Peninsula of Mexico in 2-3 days. Some weakening is anticipated when the center moves over land, and then re-strengthening is likely after it moves over the Gulf of Mexico. There will be an increase in shear over the Gulf in 4-5 days, and right now there is greater-than-normal uncertainty in how this will affect the cyclone’s intensity at that point. For now, the official forecast on days 4 and 5 shows a flat-lined intensity, and this scenario lies a little above the ICON intensity consensus and the HCCA model solution.

Key Messages:

  • 1. Tropical Depression Fourteen is expected to strengthen over the northwestern Caribbean Sea through Saturday, and it could produce tropical-storm-force winds and heavy rainfall over portions of the coast of Honduras and the Bay Islands beginning tonight through Friday. The system could be near or at hurricane strength when it reaches the Yucatan Peninsula of Mexico late Saturday, and watches could be required for a portion of that area later today.
  • 2. The system is expected to move into the south-central Gulf of Mexico as a tropical storm on Sunday. Some strengthening is anticipated while it moves northwestward over the western Gulf of Mexico early next week, but it is too soon to know exactly how strong it will get or the location and magnitude of impacts it will produce along the central or northwestern Gulf Coast. Interests in that area should continue monitoring the progress of this system over the next few days.
FORECAST POSITIONS AND MAX WINDS

INIT  20/1500Z 15.1N  79.7W   30 KT  35 MPH - Depression (WSW Negril, Jamaica)
 12H  21/0000Z 15.5N  81.9W   35 KT  40 MPH - Tropical Storm (WSW Lempira, Honduras)
 24H  21/1200Z 16.3N  84.2W   40 KT  45 MPH - Tropical Storm (ENE Barra Patuca, Honduras)
 36H  22/0000Z 17.1N  85.5W   50 KT  60 MPH - Tropical Storm (ESE Belize City, Belize)
 48H  22/1200Z 18.4N  86.4W   55 KT  65 MPH - Tropical Storm (ESE Chetumal, Mexico)
 60H  23/0000Z 19.9N  87.4W   60 KT  70 MPH - Tropical Storm (ENE Punta Allen, Mexico)
 72H  23/1200Z 21.5N  88.9W   45 KT  50 MPH - Tropical Storm (ENE Santa Clara, Mexico)
 96H  24/1200Z 25.0N  92.0W   50 KT  60 MPH - Tropical Storm (ESE Galveston, Texas)
120H  25/1200Z 28.0N  94.0W   50 KT  60 MPH - Tropical Storm (ESE Galveston, Texas)

NWS National Hurricane Center Miami FL 800 PM EDT Wed Aug 19, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A tropical wave and accompanying broad area of low pressure is producing a concentrated area of showers and thunderstorms over the central Caribbean Sea. This system is gradually becoming better organized, and a tropical depression is likely to form in a couple of days when the system reaches the northwestern Caribbean Sea. This low-pressure area is moving westward, and interests in Honduras and the Yucatan Peninsula should closely monitor its progress. Regardless of development, this disturbance will likely produce heavy rains across a large portion of Central America and southeastern Mexico late this week and this weekend. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…80 percent.
  • 2. Satellite images indicate that the low-pressure system located about 850 miles east of the Windward Islands is gradually becoming better defined. In addition, the associated showers and thunderstorms are showing signs of organization, and a tropical depression could be forming. The system is expected to move generally west-northwestward at 15 to 20 mph, and interests in the northern Leeward Islands should closely monitor its progress as tropical storm watches could be required as early as this evening. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high...90 percent.
  • 3. A tropical wave over western Africa is producing disorganized showers and thunderstorms. This wave is expected to move over the far eastern tropical Atlantic on Friday, and some slow development is possible through the weekend while it moves west-northwestward at 15 to 20 mph across the eastern tropical Atlantic. * Formation chance through 48 hours…low…10 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Wed Aug 19, 2020 

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. Showers and thunderstorms have become more concentrated today in association with a tropical wave currently located over the central Caribbean Sea. Some gradual development of this system is possible over next day or so while it moves westward at about 15 to 20 mph across the central Caribbean Sea. After that time, the wave is forecast to move more slowly west-northwestward, and a tropical depression is likely to form later this week when the system reaches the northwestern Caribbean Sea. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…80 percent.
  • 2. An elongated area of low pressure, located about 1000 miles east of the Windward Islands continues to produce a concentrated area of showers and thunderstorms. Although recent satellite-derived wind data indicates that the low is not well-defined, environmental conditions are conducive for further development, and a tropical depression is expected to form during the next day or two while the system moves generally west-northwestward at 15 to 20 mph across the central and western portions of the tropical Atlantic. Interests in the Lesser Antilles should monitor the progress of this system. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high…90 percent.
  • 3. A large area of showers and thunderstorms, located over Guinea and Sierra-Leone, Africa, is associated with a vigorous tropical wave. Environmental conditions are expected to be conducive for some development of this system while the wave enters the extreme eastern Atlantic on Friday. By early next week, however, conditions are forecast to become less favorable for tropical cyclone formation while it moves west-northwestward at 15 to 20 mph toward the central tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low...30 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Wed Aug 19, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A tropical wave located over the eastern Caribbean Sea is producing disorganized showers and thunderstorms, along with gusty winds in these thunderstorms. Some gradual development of this system is possible over next day or so while it moves westward at about 15 to 20 mph across the central Caribbean Sea. After that time, the wave is forecast to move more slowly west-northwestward, and a tropical depression is likely to form late this week or this weekend when the system reaches the northwestern Caribbean Sea. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high…80 percent.
  • 2. An elongated area of low pressure, located a little over 1000 miles east of the Windward Islands continues to produce a concentrated area of showers and thunderstorms mainly on the west side of the disturbance. Environmental conditions are conducive for further development, and a tropical depression is expected to form during the next day or two while the system moves generally west-northwestward at 15 to 20 mph across the central and western portions of the tropical Atlantic. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high…90 percent.
  • 3. A large area of showers and thunderstorms, located over Guinea and Sierra-Leone, Africa, is associated with a vigorous tropical wave. Environmental conditions are expected to be marginally conducive for some development of this system while the wave enters the extreme eastern Atlantic on Friday. By early next week, however, conditions are forecast to become less favorable for tropical cyclone formation while it moves west-northwestward at 15 to 20 mph toward the central tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Tue Aug 18, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A tropical wave located over the eastern Caribbean Sea is producing a large area of cloudiness and disorganized thunderstorms, along with strong gusty winds on the north side of the disturbance. Significant development of this system is unlikely during the next day or so while it moves quickly westward at about 20 mph across the eastern and central Caribbean Sea. After that time, however, the wave is forecast to move more slowly west-northwestward, and a tropical depression is likely to form late this week or this weekend when the system reaches the northwestern Caribbean Sea. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high…80 percent.
  • 2. A broad and elongated area of low pressure located about 1000 miles west-southwest of the Cabo Verde Islands continues to produce a concentrated area of showers and thunderstorms on the west side of the disturbance. Environmental conditions are conducive for further development, and a tropical depression is expected to form during the next day or two while the system moves generally west- northwestward at 15 to 20 mph across the central and western portions of the tropical Atlantic. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high…90 percent.

NWS Weather Prediction Center College Park MD 200 PM EDT Tue Aug 18, 2020 

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A tropical wave over the eastern Caribbean Sea continues to produce an area of disorganized thunderstorms and gusty winds. This wave is moving quickly westward at about 20 mph and significant development is unlikely while it moves across the eastern and central Caribbean Sea during the next day or two. After that time, however, the wave is forecast to slow down, and a tropical depression will likely form late this week or this weekend when it reaches the northwestern Caribbean Sea. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…high…70 percent.
  • 2. An area of low pressure located about 1300 miles east of the Lesser Antilles is producing a concentrated area of showers and thunderstorms. Environmental conditions are conducive for development, and a tropical depression is expected to form within the next couple of days while the system moves west-northwestward at 15 to 20 mph across the central and western portions of the tropical Atlantic. Interests in the Lesser Antilles should monitor the progres of this system. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Tue Aug 18, 2020 

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A tropical wave over the eastern Caribbean Sea is producing an area of disorganized thunderstorms and gusty winds. Significant development of this system is unlikely during the next couple of days while it moves quickly westward at about 20 mph across the eastern and central Caribbean Sea. After that time, however, the wave is forecast to move more slowly westward, and a tropical depression could form late this week or this weekend when it reaches the northwestern Caribbean Sea. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…60 percent.
  • 2. A broad area of low pressure located about 900 miles west-southwest of the Cabo Verde Islands is producing a concentrated area of showers and thunderstorms. Environmental conditions are conducive for further development, and a tropical depression is likely to form within the next couple of days while the system moves westward to west-northwestward at 15 to 20 mph across the central and western portions of the tropical Atlantic. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 200 AM EDT Tue Aug 18, 2020 

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. Disorganized showers and thunderstorms continue in association with a tropical wave located over the eastern Caribbean Sea. This disturbance is moving westward at about 20 mph, and is forecast to continue to move quickly westward over the eastern and central Caribbean Sea during the next couple of days, which is likely to limit significant development. After that time, however, the system is forecast to move more slowly westward across the western Caribbean, where upper-level winds could become more conducive for the development of a tropical depression during the latter part of this week. Regardless of development, locally heavy rainfall and gusty winds are expected over portions of the Windward and southern Leeward Islands this morning. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…60 percent.
  • 2. A broad area of low pressure located a little over 700 miles west-southwest of the Cabo Verde Islands is producing a concentrated area of showers and thunderstorms displaced to the west of an elongated surface circulation. Environmental conditions are conducive for further development, and a tropical depression is likely to form within the next day or two while the system moves westward to west-northwestward at 15 to 20 mph across the central and western portions of the tropical Atlantic. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Mon Aug 17, 2020 

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A tropical wave near the Windward Islands continues to produce a large area of disorganized showers and thunderstorms. This disturbance is moving westward at about 20 mph, and is expected to continue to move quickly westward over the eastern and central Caribbean Sea during the next couple of days, which is likely to limit significant development. After that time, however, the system is forecast to move more slowly westward across the western Caribbean, where upper-level winds could become more conducive for the development of a tropical depression during the latter part of this week. Regardless of development, locally heavy rainfall and gusty winds are expected over portions of the Windward and southern Leeward Islands through Tuesday morning. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…60 percent.
  • 2. Satellite images indicate that a broad area of low pressure located about 700 miles west-southwest of the Cabo Verde Islands has become better organized since yesterday, with increasing banding features near the center. Environmental conditions are conducive for further development, and a tropical depression is likely to form within a couple days while the system moves westward to west-northwestward at 15 to 20 mph across the central and western portions of the tropical Atlantic. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Mon Aug 17, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A tropical wave approaching the Windward Islands is producing a large area of disorganized shower and thunderstorm activity. This disturbance is moving westward at about 20 mph, and is expected to continue to move quickly westward over the eastern and central Caribbean Sea during the next couple of days, which is likely to limit significant development. After that time, however, the system is expected to move more slowly westward across the western Caribbean, where upper-level winds could become more conducive for the development of a tropical depression during the latter part of this week. Regardless of development, locally heavy rainfall and gusty winds are expected over portions of the Windward and southern Leeward Islands through Tuesday morning. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…50 percent.
  • 2. A tropical wave over the eastern tropical Atlantic is forecast to interact with another disturbance located several hundred miles southwest of the Cabo Verde Islands within the next day or two. This interaction is expected to lead to the formation of a broad area of low pressure, and conditions are forecast to be conducive for the development of a tropical depression during the middle-to-latter part of this week while the system moves westward to west- northwestward at 15 to 20 mph across the central and western portions of the tropical Atlantic. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…high…70 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Mon Aug 17, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A fast-moving tropical wave located a couple of hundred miles east of the Windward Islands continues to produce disorganized shower and thunderstorm activity. This disturbance is expected to move westward at about 20 mph during the next few days, and that fast forward speed is likely to limit significant development while the system approaches the Windward and southern Leeward Islands today, and moves across the eastern and central Caribbean Sea on Tuesday and Wednesday. After that time, however, the system is expected to move more slowly westward across the western Caribbean Sea, where upper-level winds could become more conducive for the development of a tropical depression during the latter part of this week. Regardless of development, locally heavy rainfall and gusty winds are expected over portions of the Windward and southern Leeward Islands beginning today through Tuesday morning. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…50 percent.
  • 2. Another tropical wave located over the eastern tropical Atlantic to the south-southwest of the Cabo Verde Islands is producing disorganized cloudiness and showers. The wave is forecast to move westward to west-northwestward at 15 to 20 mph during the next few days, and environmental conditions are expected to become more conducive for the development of a tropical depression during the middle-to-latter part of this week while the system moves across the central and western portions of the tropical Atlantic. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…60 percent.

NWS National Hurricane Center Miami FL 200 AM EDT Mon Aug 17, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

  • 1. A fast-moving tropical wave located about 400 miles east of the Windward Islands continues to produce disorganized shower and thunderstorm activity. This disturbance is expected to move westward at about 20 mph during the next few days, and that fast forward speed is likely to limit significant development while the system approaches the Windward and southern Leeward Islands today, and moves across the eastern and central Caribbean Sea on Tuesday and Wednesday. After that time, however, the system is expected to move more slowly westward across the western Caribbean Sea, where upper-level winds could become more conducive for the development of a tropical depression during the latter part of this week. Regardless of development, locally heavy rainfall and gusty winds are expected over portions of the Windward and southern Leeward Islands beginning this evening through Tuesday morning. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…50 percent.
  • 2. Another tropical wave located over the far eastern tropical Atlantic well to the south-southeast of the Cabo Verde Islands is producing a large area of cloudiness and disorganized showers. The wave is forecast to move westward to west-northwestward at 15 to 20 mph during the next few days, and environmental conditions are expected to become more conducive for the development of a tropical depression during the middle-to-latter part of this week while the system moves across the central tropical Atlantic. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…medium…60 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Sun Aug 16, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center has issued the last advisory on Post-Tropical Cyclone Josephine, located a couple of hundred miles north of San Juan, Puerto Rico.

  • 1. Shower and thunderstorm activity has continued to increase in association with a fast-moving tropical wave located about 500 miles east of the Windward Islands. This disturbance is expected to move westward at about 20 mph during the next few days, and that fast forward speed is likely to limit significant development while the system approaches the Windward and southern Leeward Islands on Monday, and moves across the eastern Caribbean Sea on Tuesday. After that time, however, the system is expected to move more slowly westward across the central and western Caribbean Sea, where upper-level winds could become more conducive for the development of a tropical depression during the middle-to-latter part of this week. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium...50 percent.
  • 2. Another tropical wave located over the far eastern tropical Atlantic well to the southeast of the Cabo Verde Islands is producing a large area of cloudiness and disorganized showers. The wave is forecast to move westward at 15 to 20 mph during the next few days, and environmental conditions are expected to become more conducive for the development of a tropical depression during the middle-to- latter part of this week while the system moves across the central tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Sun Aug 16, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Depression Josephine, located a couple of hundred miles north-northeast of San Juan, Puerto Rico.

  • 1. Shower and thunderstorm activity has increased in association with a fast-moving tropical wave located about 700 miles east of the Windward Islands. This system is expected to move westward at about 20 mph during the next few days, and that fast speed is likely to limit significant development while the system approaches the Windward and southern Leeward Islands Monday, and moves across the eastern Caribbean Sea on Tuesday. After that time, the system is expected to move more slowly westward across the central and western Caribbean Sea, and upper-level winds could be conducive for development during the middle to latter part of this week. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. Another tropical wave located over the far eastern tropical Atlantic is producing a large area of cloudiness and showers. This wave is forecast to move westward at 15 to 20 mph during the next few days, and some development will be possible by the middle to latter part of the week as environmental conditions become more conducive while the system is over the central tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium...40 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Sun Aug 16, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Storm Josephine, located a couple of hundred miles northeast of San Juan, Puerto Rico. The National Hurricane Center has issued the last advisory on Post-Tropical Cyclone Kyle, located several hundred miles southwest of Cape Race, Newfoundland.

  • 1. A fast-moving tropical wave located about 850 miles east of the Windward Islands is producing a small area of disorganized showers and thunderstorms. This system is expected to move westward at about 20 mph during the next few days, and that fast speed is likely to limit development while the system approaches the Windward and southern Leeward Islands today and Monday and moves across the eastern Caribbean Sea on Tuesday. After that time, the system is expected to move more slowly westward across the central and western Caribbean Sea, and upper-level winds could be conducive for development during the middle to latter part of this week. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…30 percent.
  • 2. Another tropical wave located just west of the coast of Africa is producing a large area of cloudiness and showers. This wave is forecast to move westward at 15 to 20 mph during the next few days, and some development will be possible by the middle to latter part of the week as environmental conditions become more conducive while the system is over the central tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 200 AM EDT Sun Aug 16, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Storm Josephine, located just over a hundred miles north-northeast of the northern Leeward Islands, and on Tropical Storm Kyle, located several hundred miles southwest of Cape Race, Newfoundland.

  • 1. A fast-moving tropical wave located over the central tropical Atlantic several hundred miles east of the Windward Islands is producing a small area of disorganized showers and thunderstorms. This system is expected to move westward at about 20 mph during the next few days, and that fast speed is likely to limit development while the system approaches the Windward and southern Leeward Islands today and Monday and moves across the eastern Caribbean Sea on Tuesday. After that time, the system is expected to move more slowly westward across the central and western Caribbean Sea, and upper-level winds could be conducive for development during the middle to latter part of this week. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…30 percent.
  • 2. Another tropical wave moving off the coast of Africa is producing a large area of cloudiness and showers. This wave is forecast to move westward at 15 to 20 mph during the next few days, and some development will be possible by the middle to latter part of the week as environmental conditions become more conducive while the system is over the central tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Sat Aug 15, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Storm Josephine, located over the tropical Atlantic Ocean a few hundred miles northeast of the northern Leeward Islands, and on Tropical Storm Kyle, located several hundred miles southeast of the New England states of the United States.

  • 1. A westward-moving tropical wave located over the central tropical Atlantic several hundred miles east of the Windward Islands is currently producing limited shower and thunderstorm activity. However, upper-level winds are expected to become a little more conducive for development by the middle of next week as the disturbance approaches the central and southern Lesser Antilles and moves into the eastern Caribbean Sea. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…20 percent.

If this system is named, it will become Tropical Storm Marco.

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Video: 10 PM Update: Tropical Storm Laura enters Gulf of Mexico; Marco downgraded to Tropical Depression