Tropical Storm Hanna

Tropical Depresssion Hanna Track 1600 Hours July 26 2020
Tropical Depresssion Hanna Track 1600 Hours July 26 2020

Tropical Depresssion Hanna Impact AreaTropical Storm Hanna – NWS National Hurricane Center Miami FL 400 PM CDT Sun Jul 26, 2020 (see NEW video below)

Surface observations along with radar and satellite imagery show that Hanna continues to weaken as it moves farther inland. There have been no recent observations of sustained tropical-storm-force winds, and Doppler velocities have continued to decrease. Based on these trends, the initial wind speed has been reduced to 30 kt. Hanna should continue to spin down while it moves over the high terrain of northeastern Mexico. The system is forecast to become a remnant low in 12-18 hours, and should dissipate over the mountains of Mexico by late Monday, if not sooner. Hanna is moving west-southwestward or 245/8 kt. The cyclone should continue on this general heading and speed until dissipation occurs. The updated NHC track forecast is again similar to the previous advisory and is close to the dynamical model consensus. This is the last NHC advisory on Hanna.

Key Messages

  • 1. Heavy rainfall from Hanna has already produced numerous reports of flash flooding across south Texas. Additional heavy rainfall will continue to result in life-threatening flash flooding over south Texas and northern Mexico, and isolated minor river flooding in south Texas.
FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 25.6N 100.6W   30 KT  35 MPH - Depression (WSW Rancho Carvajal, Mexico)
 12H  27/0600Z 25.2N 101.6W   25 KT  30 MPH - Depression (WSW General Treviño, Mexico)
 24H  27/1800Z 25.0N 102.6W   20 KT  25 MPH - Low (WSW Bajio de Ahuichila, Mexico)
 36H  28/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Sun Jul 26, 2020 

Surface observations and WSR-88D radar data from Brownsville, Texas, indicate that Hanna continues to weaken as it moves farther inland. The radar shows a couple of fairly well-defined bands of convection over the eastern semicircle and tropical-storm-force wind gusts have been reported at observing sites along the U.S./Mexico border within the past couple of hours. The initial intensity has been reduced to 40 kt, and is based primarily on recent observations and Doppler radar velocities. Hanna should continue to weaken quickly during the next 12-24 hours as it moves inland over Mexico. Hanna is forecast to become a tropical depression later today and dissipate over the mountainous terrain of Mexico by Monday night.

Hanna is moving west-southwestward or 250/8 kt. The system is forecast to continue moving west-southwestward around the southern portion of a mid-level ridge over the central United States. The new NHC track forecast is similar to the previous advisory and lies near the various consensus aids.

Key Messages

  • 1. Tropical storm conditions are expected to persist into this afternoon near and to the east of the center of Hanna.
  • 2. Heavy rainfall from Hanna has already produced numerous reports of flash flooding across south Texas. Additional heavy rainfall will continue to cause life-threatening flash flooding over south Texas and northern Mexico, and isolated minor to moderate river flooding in south Texas.
  • 3. Storm surge along the Texas coast should continue to diminish today.
FORECAST POSITIONS AND MAX WINDS

INIT  26/1500Z 26.1N  99.7W   40 KT  45 MPH - Tropical Storm (WSW General Treviño, Mexico)
 12H  27/0000Z 25.5N 100.6W   30 KT  35 MPH - Depression (WSW Monterrey, Mexico)
 24H  27/1200Z 25.0N 101.9W   25 KT  30 MPH - Low (WNW General Cepeda, Mexico)
 36H  28/0000Z 24.9N 102.9W   20 KT  25 MPH - Low (WSW Huariche )
 48H  28/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Sat Jul 25, 2020 

Hanna made landfall around 2200 UTC over Padre Island, Texas, and then made a second landfall a little more than an hour later in eastern Kenedy County, Texas. The estimated intensity was 80 kt for both of those landfalls. Since then, Hanna has been moving inland over southern Texas and has weakened. The initial intensity is lowered to 65 kt for this advisory, based on Doppler radar velocity data and surface observations. Even though the hurricane has weakened some, it still has an impressive appearance in radar images with an eye, eyewall, and rainbands evident.

The storm is moving west-southwestward at 8 kt, steered by a mid-level ridge situated to its north over the central United States. This motion should continue, taking Hanna across extreme southern Texas overnight and across northeastern Mexico on Sunday. The new NHC track forecast is just a little south of the previous one, trending toward the latest consensus models.

Now that Hanna is inland, rapid weakening is forecast. Hanna should fall below hurricane strength in the next few hours and weaken to a tropical depression by late Sunday. Hanna is forecast to dissipate over the rugged terrain of Mexico on Monday.

Key Messages

  • 1. Life-threatening storm surge will continue along portions of the Texas coast from Port Mansfield to Port O’Connor, where a Storm Surge Warning is in effect. Residents in these locations should follow advice given by local emergency officials.
  • 2. Hurricane conditions will continue within the Hurricane Warning area along the Texas coast for a few more hours. Strong winds are expected to spread farther inland across portions of south Texas where a Tropical Storm Warning is in effect.
  • 3. Hanna is expected to produce heavy rains across portions of southern Texas and northeastern Mexico. These rains will result in life-threatening flash flooding and isolated minor to moderate river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 26.6N  98.0W   65 KT  75 MPH - Category 1 (WNW Raymondville, TX)
 12H  26/1200Z 26.2N  99.1W   45 KT  50 MPH - Tropical Storm (WNW Alto Bonito, MX)
 24H  27/0000Z 25.4N 100.6W   30 KT  35 MPH - Low (WNW Los Lirios, MX)
 36H  27/1200Z 24.6N 101.9W   20 KT  25 MPH - Low (WSW Mazapil, MX)
 48H  28/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Sat Jul 25, 2020 

NOAA Doppler weather radar data from Brownsville and Corpus Christi, Texas, along with reconnaissance data from the Air Force Hurricane Hunters indicate that Hanna has continued to strengthen this afternoon. A 30-nmi-wide eye remains distinct in the radar data, and dropsonde and 700-mb flight-level-level height data from the aircraft indicate that the central pressure has decreased to 973 mb. The aircraft measured a peak 700-mb flight-level wind speed of 86 kt on its last outbound leg, which equates to about 77 kt at the surface. Coincident with the flight-level wind data were SFMR surface wind speeds of 80 kt. In addition, Doppler velocity values have been averaging close to 100 kt between 5000-6000 ft in the northern and northeastern eyewall, which converts to 80-kt surface wind speed estimates. Based on these data, the initial intensity has been increased to 80 kt. No further strengthening is anticipated before the center of Hanna’s eye makes landfall along the south Texas coast in a few hours.

Doppler radar and aircraft reconnaissance fixes indicate that Hanna has finally made the much anticipated turn toward the west-southwest, now showing an initial motion of 255/07 kt. A west-southwestward motion is expected to continue for the next 48 hours, which will take Hanna well inland over south Texas, followed by eventual dissipation in about 48 h over over the mountains of northeastern Mexico. The new NHC track forecast remains unchanged from the previous advisory, and lies near the center of the tightly packed consensus models.

Key Messages

  • 1. Life-threatening storm surge will continue along portions of the Texas coast from Port Mansfield to Sargent, where a Storm Surge Warning is in effect. Residents in these locations should follow advice given by local emergency officials.
  • 2. Hurricane conditions will continue within the Hurricane Warning area along the Texas coast through this evening. Strong winds will also spread inland across portions of South Texas where Tropical Storm and Hurricane Warnings are in effect.
  • 3. Hanna is expected to produce heavy rains across portions of southern Texas and northeastern Mexico. These rains will result in life-threatening flash flooding and isolated minor to moderate river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  25/2100Z 26.8N  97.2W   80 KT  90 MPH - Category 1 (E Padre Island, TX)
 12H  26/0600Z 26.7N  98.4W   50 KT  60 MPH - Tropical Storm (WNW La Reforma, Mexico)
 24H  26/1800Z 26.0N 100.0W   30 KT  35 MPH - Low (ENE Higueras, Mexico)
 36H  27/0600Z 25.5N 101.4W   20 KT  25 MPH - Low (WDW  La Rosa, Mexico)
 48H  27/1800Z...DISSIPATED INLAND

NWS National Hurricane Center Miami FL 1000 AM CDT Sat Jul 25, 2020

NOAA Doppler radar data from Corpus Christi and Brownsville, Texas, along with reconnaissance data from the NOAA Hurricane Hunters indicate that Hanna has continued to strengthen this morning. A well-defined but fairly large 30-35-nmi-wide eye has formed and recent dropsonde data from the eye indicate that the central pressure has dropped to 978 mb.

The aircraft measured a peak 700-mb flight-level wind speed of 77 kt, which equates to about 69 kt at the surface. During the past hour, Doppler velocities have sharply increased with numerous patches of 85-90 kt between 7000-8000 ft common in the northern eyewall. Although these values would typically correspond to surface winds of about 75 kt, the Doppler velocity are occurring in low reflectivity regions of 25-30 dBZ, so the full effect of those winds are likely not reaching the surface. This could be why the highest SFMR surface wind observed by the aircraft was only 63 kt. The initial intensity has been increased to 70 kt, which is a blend of the aircraft flight-level, radar, and SFMR surface wind speed estimates.

The center position is a tad north of the recon fixes due to some southward tilt of the eye caused by northerly shear. This has resulted in a slower westward motion of 270/06 kt. The ridge to the north of the hurricane has been slowly building westward and southwestward based on upper-air data over the past 24 hours. This slow ridging pattern is expected to continue for the next 48 hours, resulting in Hanna gradually turning toward the west-southwest by late this afternoon or evening, with landfall occurring in about 12 h along south Texas coast. After landfall, Hanna should continue its west-southwestward motion until dissipation over the mountainous terrain of northeastern Mexico in 48-60 h. The new NHC track forecast is similar to the previous advisory track, and lies close to the tightly packed consensus model guidance.

Although the deep-layer vertical wind shear is expected to remain out of the north-northwest to north at about 20 kt, the relatively large and stable eye, along with the expected convective vigor of the hurricane, could result in a little more strengthening just before landfall occurs. After landfall, rapid weakening of the wind field is expected. However, the weakening peak winds will have no negative effect on the likelihood for heavy rainfall or the possibility of isolated tornadoes developing.

Key Messages

  • 1. Life-threatening storm surge is occurring along portions of the Texas coast from Port Mansfield to Sargent, where a Storm Surge Warning is in effect. Residents in these locations should follow advice given by local emergency officials.
  • 2. Hurricane conditions are expected along the Texas coast from Port Mansfield to Mesquite Bay, where a Hurricane Warning is in effect. Tropical storm conditions are expected to first reach the coast within the warning area this morning.
  • 3. Hanna is expected to produce heavy rains across portions of southern Texas and northeastern Mexico. These rains could result in life-threatening flash flooding and isolated minor to moderate river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 27.1N  96.3W   70 KT  80 MPH - Category 1 (ESE Port Aransas, TX)
 12H  26/0000Z 26.9N  97.6W   70 KT  80 MPH - Category 1 (ESE Armstrong, TX)
 24H  26/1200Z 26.4N  99.1W   45 KT  50 MPH - Tropical Storm (WSW Fronton, MX)
 36H  27/0000Z 25.9N 100.6W   25 KT  30 MPH - Low (WNW Garcia, MX)
 48H  27/1200Z 25.3N 102.1W   15 KT  15 MPH - Low (WSW Huariche, MX)
 60H  28/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Fri Jul 24, 2020

Hanna continues to strengthen over the northwestern Gulf of Mexico. Satellite and Doppler radar images indicate that the inner core continues to become better organized and the outer bands are now more symmetrical around the center.

The NOAA Hurricane Hunters are currently investigating Hanna and have found maximum 850 mb flight-level winds of 72 kt and maximum SFMR winds of 51 kt. Based on this data, the initial intensity is increased to 55 kt for this advisory. The aircraft has also reported a minimum pressure of 992 mb, which is a 8 mb drop from the flight earlier today. The NOAA aircraft data indicate that the center has moved a little south of west during the past few hours, and the storm is now a little south of the previous forecast track. A strengthening subtropical ridge over the central U.S. should cause the storm to continue to move generally westward, taking the center across the southern Texas coast tomorrow afternoon or early evening. After landfall, the storm is expected to turn to the west-southwest or southwest across extreme southern Texas and northern Mexico, and that motion should continue until the system dissipates.

Hanna still has another 18 hours or so to strengthen as it remains in light wind shear conditions and over the warm Gulf of Mexico waters. Since the structure of the system continues to improve, it seems likely that Hanna will reach hurricane intensity before it makes landfall. The peak intensity could be higher than what is shown in the intensity forecast below since landfall is expected to occur between the 12 and 24 h forecast times. After landfall, rapid weakening is anticipated, and Hanna is expected to dissipate on Monday over the rugged terrain of northern Mexico. The NHC intensity forecast lies at the high end of the model guidance for the next 24 h.

Key Messages

  • 1. There is a danger of life-threatening storm surge along the Texas coast from Baffin Bay to Sargent, where a Storm Surge Warning is in effect. Residents in these locations should follow advice given by local emergency officials.
  • 2. Hurricane conditions are expected along the Texas coast from Port Mansfield to Mesquite Bay, where a Hurricane Warning is in effect. Tropical storm conditions are expected to first reach the coast within the warning area Saturday morning.
  • 3. Hanna is expected to produce heavy rains across portions of southern Texas and northeastern Mexico. These rains could result in life-threatening flash flooding and isolated minor to moderate river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  25/0300Z 27.1N  94.8W   55 KT  65 MPH - Tropical Storm (ESE Corpus Christi, TX)
 12H  25/1200Z 27.1N  96.1W   65 KT  75 MPH - Category 1 (ENE Padre Island, TX)
 24H  26/0000Z 27.0N  97.7W   60 KT  70 MPH - Tropical Storm (ENE  Armstrong, TX)
 36H  26/1200Z 26.6N  99.3W   35 KT  40 MPH - Tropical Storm (ESE El Rebote, Mexico)
 48H  27/0000Z 25.9N 101.0W   25 KT  30 MPH - Low (WSW Paredón, Mexico)
 60H  27/1200Z 25.2N 102.4W   20 KT  25 MPH - Low (ESE De Parras, Mexico)
 72H  28/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Fri Jul 24, 2020

Satellite imagery, along with Doppler radar data from Houston and Corpus Christi, indicate that Hanna has been getting better organized over the past several hours. Curved banding features have improved and a banding eye has developed in the radar data. The NOAA reconnaissance aircraft reported SFMR winds of 43-45 kt on its last outbound leg and a ship D5DE5 just east of the center reported an elevated wind speed of 51 kt at 1400Z. Based on these data, along with an estimated pressure of 999 mb from surrounding oil rigs, the initial intensity has been conservatively increased to 45 kt.

Reconnaissance and radar fix data indicate that Hanna has turned westward, and the motion is now 275/09 kt. Hanna is forecast to move generally westward along the southern periphery of a deep-layer ridge for the next 24 hours, with landfall expected along the south-central coast of Texas within the hurricane warning area Saturday afternoon or early evening. The new NHC forecast track is just an extension of the previous advisory track, and lies close to an average of the consensus models TVCN, NOAA-HCCA, and FSSE.

Given the improved internal structure noted in radar imagery, along with SSTs of at least 30 deg C and an impressive outflow pattern, increased frictional convergence as the cyclone moves closer to the coast and the approaching nocturnal convective maximum should support additional strengthening, and Hanna is now forecast to become a hurricane prior to making landfall. The NHC forecast of 65 kt in 24 hours is between the latest HWRF model run, which brings Hanna to 70 kt just prior to landfall, and the intensity consensus models HCCA and IVCN, which are just below hurricane strength.

Due to Hanna forecast to reach hurricane strength, Hurricane and Storm Surge Warnings have been issued for portions of the Texas coast.

Key Messages

  • 1. There is a danger of life-threatening storm surge along the Texas coast from Baffin Bay to Sargent, where a Storm Surge Warning is in effect. Residents in these locations should follow advice given by local emergency officials.
  • 2. Hurricane conditions are expected along the Texas coast from Baffin Bay to Mesquite Bay, where a Hurricane Warning is in effect. Tropical storm conditions are expected to first reach the coast within the warning area Saturday morning.
  • 3. Hanna is expected to produce heavy rains across portions of southern Texas and northeastern Mexico. These rains could result in life-threatening flash flooding and isolated minor to moderate river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  24/2100Z 27.3N  94.3W   45 KT  50 MPH - Tropical Storm (ESE Port Aransas, TX)
 12H  25/0600Z 27.4N  95.6W   55 KT  65 MPH - Tropical Storm (ESE Port Aransas, TX)
 24H  25/1800Z 27.3N  97.2W   65 KT  75 MPH - Category 1 (ESE Padre Island, TX)
 36H  26/0600Z 27.0N  98.6W   40 KT  45 MPH - Tropical Storm (ENE Agua Nueva, TX)
 48H  26/1800Z 26.6N 100.3W   25 KT  30 MPH - Low (ENE Bustamante, Mexico)
 60H  27/0600Z 25.6N 102.0W   20 KT  25 MPH - Low(ESE Paila, Mexico)
 72H  27/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Fri Jul 24, 2020

Reports from a NOAA reconnaissance aircraft this morning and nearby ship D5DY4 indicate that Hanna has strengthened a little. However, the aircraft data also showed that Hanna’s center had moved or reformed a little farther north near the northern edge of the convective cloud mass. A partial SSMI/S pass around 1231Z suggested that a mid-level eye feature could be forming, but it also possible that a dry slot may be intruding into the cloud shield from the northwest and west. The initial intensity of 40 kt is based on aircraft SFMR surface winds of 38-40 kt, and the 1200Z D5DY5 ship report of 48 kt at 89 meters elevation, which reduces to a 38-kt 10-meter wind speed.

Even with the earlier northwestward jump in the center position, reconnaissance and microwave satellite data indicate that Hanna’s motion is still west-northwestward or 285/08 kt. There remains no significant change to the previous official track forecast or reasonings over the past couple of days. The latest NHC model guidance remains in good agreement that mid-level ridge will build to the north and northwest of Hanna over the next couple of days, resulting in the cyclone turning westward by tonight and on Saturday. It should then turn west-southwestward Saturday night and Sunday. The new NHC forecast track continues to show the center making landfall along the south-central coast of Texas within the tropical storm warning area Saturday afternoon or evening, which is in good agreement with the various consensus models.

Hanna’s convective cloud shield remains very asymmetrical with the bulk of the convection confined to the southern semicircle despite the otherwise symmetrical and expanding upper-level outflow pattern. More recently, some deep convection has developed near the center and the aforementioned possible mid-level eye feature. Hanna is forecast to remain in relatively low vertical wind shear regime and over SSTs of 30C or more, a combination that typically favors significant intensification. However, nearby dry mid-level air noted in 1200Z soundings from Corpus Christi and Brownsville has been eroding and preventing convection from developing in the northwest quadrant and near the center, which has inhibited strengthening over the past couple of days despite the low shear conditions. The latest global model guidance shows the dry air mixing out in about 24 h just prior to landfall, which should allow for at least gradual strengthening until landfall occurs in about 30 h or so. However, if an eyewall forms during the next 12 h, then it is possible that Hanna could be near 60 kt when it makes landfall. The new NHC intensity forecast is similar to the previous advisory, and is a blend of the IVCN and HCCA consensus intensity forecasts.

Key Messages

  • 1. Hanna is forecast to strengthen and it is expected to bring tropical-storm-force winds to portions of the Texas coast, where a tropical storm warning is in effect.
  • 2. Hanna is expected to produce heavy rains across portions of southern Texas. These rains could result in flash flooding and isolated minor to moderate river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  24/1500Z 27.2N  93.2W   40 KT  45 MPH - Tropical Storm (ESE Galveston, TX)
 12H  25/0000Z 27.5N  94.6W   45 KT  50 MPH - Tropical Storm (ESE Corpus Christi, TX)
 24H  25/1200Z 27.4N  96.2W   55 KT  65 MPH - Tropical Storm (ESE Port Aransas, TX)
 36H  26/0000Z 27.3N  97.6W   50 KT  60 MPH - Tropical Storm (ENE Riviera Beach, TX)
 48H  26/1200Z 27.0N  99.0W   35 KT  40 MPH - Tropical Storm (ESE Escobas, TX)
 60H  27/0000Z 26.3N 100.4W   25 KT  30 MPH - Low (WNW Salinas Victoria, Mexico)
 72H  27/1200Z 25.7N 101.6W   15 KT  15 MPH - Low (ENE Marta, Mexico)
 96H  28/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 PM CDT Thu Jul 23, 2020 

The system continues to organize with curved bands becoming better established around the center. The cyclone certainly has the appearance of a tropical storm, and just minutes ago the NOAA Hurricane Hunters found winds to support upgrading the system to a 35-kt tropical storm. Data from the aircraft also show that the minimum pressure has dropped to 1002 mb, indicating that the system is on a developing trend.

Hanna is moving fairly slowly to the west-northwest, with the latest initial motion estimated to be 285/6 kt. This west-northwest motion should continue on Friday, but a turn to the west is expected by Friday night as a subtropical ridge strengthens to the north of the cyclone. This steering flow should take the center of the storm across the southern Texas coast in 36 to 48 hours. After landfall, the storm is forecast to turn south of west across extreme southern Texas and northern Mexico. The models have shifted southward again this cycle, and the NHC track forecast has been adjusted in that direction.

Additional strengthening seems quite likely until the storm makes landfall since it is expected to remain over the very warm Gulf of Mexico waters and in generally low wind shear conditions. After landfall, steady weakening should commence, and the cyclone should dissipate over the rugged terrain of northern Mexico in about 4 days. The NHC intensity forecast is a little above the previous one and at the high end of the guidance given the system’s well organized structure and favorable environment. Due to the southward shift in the track forecast, the tropical storm warning has been extended southward from Port Mansfield to the Mouth of the Rio Grande.

Tropical Storm Hanna is the earliest 8th storm on record. The previous record was in 2005 when Harvey formed on August 3rd.

Key Messages

  • 1. Hanna is forecast to strengthen and it is expected to bring tropical-storm-force winds to portions of the Texas coast, where a tropical storm warning is in effect.
  • 2. Hanna is expected to produce heavy rains across portions of Louisiana, southern Texas, and northern Mexico. These rains could result in flash flooding and isolated minor-to-moderate river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  24/0300Z 26.2N  91.4W   35 KT  40 MPH - Tropical Storm (ESE Galveston, TX)
 12H  24/1200Z 26.6N  92.8W   40 KT  45 MPH - Tropical Storm (ESE Galveston, TX)
 24H  25/0000Z 27.1N  94.5W   45 KT  50 MPH - Tropical Storm (ESE Port Aransas, TX)
 36H  25/1200Z 27.2N  96.3W   55 KT  65 MPH - Tropical Storm (ESE Padre Island, TX)
 48H  26/0000Z 27.2N  97.8W   45 KT  50 MPH - Tropical Storm (WSW Sarita, TX)
 60H  26/1200Z 27.0N  99.3W   30 KT  35 MPH - Low (ENE Zapata, TX)
 72H  27/0000Z 26.5N 100.5W   25 KT  30 MPH - Low (ESE Bustamante, MX)
 96H  28/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 400 PM CDT Thu Jul 23, 2020 

Satellite imagery indicates that the depression continues to become better organized, with the center near the eastern edge of a large and broadly curved convective area, with a second curved band to the east. Several subjective and objective satellite intensity estimates have increased to 35 kt since the last advisory. However, surface observations, scatterometer data, and data from an earlier Air Force Reserve Hurricane Hunter mission show a large area of 25-30 kt winds south and east of the center, and no 35-kt winds to justify an upgrade at this time. Thus, the initial intensity remains 30 kt. A NOAA Hurricane Hunter aircraft is scheduled to investigate the depression this evening, and the current expectation is that they will find it is a tropical storm.

The center meandered a bit today, possibly due to reformation. However, the system now seems to have resumed a west-northwestward motion of 285/7 kt. A mid-level ridge over the central United States is the predominant steering influence, and the global models forecast this ridge to build somewhat during the next several days. This should cause the depression to turn westward by 36-48 h and south of west after about 60 h. The track guidance remains in good agreement with that scenario, although there has been a slight southward shift in the guidance envelope and the consensus models. The new NHC forecast track is also shifted a little southward and has the center making landfall along the Texas coast in about 48 h.

The depression is in an environment of light shear with good anticyclonic outflow, and it will be over warm sea surface temperatures until landfall. This should allow steady strengthening. The new NHC intensity forecast has been increased to show a peak intensity of 50 kt just before landfall, followed by steady weakening and eventually dissipation after landfall. The new intensity forecast is close to the intensity consensus.

The aircraft and scatterometer data show that the strongest winds in the cyclone are currently occurring about 70-90 n mi from the center. This has caused the forecast wind radii to be expanded, and as a result a Tropical Storm Warning is needed for portions of the Texas coast.

Key Messages

  • 1. The depression is expected to strengthen and it is likely to bring tropical-storm-force winds to portions of the Texas coast, where a tropical storm warning has been issued.
  • 2. The tropical cyclone is expected to produce heavy rains across portions of Louisiana, southern Texas, and northern Mexico. These rains could result in flash flooding and isolated minor-to-moderate river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  23/2100Z 26.1N  90.7W   30 KT  35 MPH - Depression (ESE Port Eads, LA)
 12H  24/0600Z 26.5N  91.9W   35 KT  40 MPH - Tropical Storm (ESE Galveston, Texas)
 24H  24/1800Z 27.1N  93.6W   45 KT  50 MPH - Tropical Storm (ESE Galveston, Texas)
 36H  25/0600Z 27.5N  95.3W   50 KT  60 MPH - Tropical Storm (ESE Port Aransas, Texas)
 48H  25/1800Z 27.6N  97.0W   50 KT  60 MPH - Tropical Storm (ESE Mustang Island, Texas)
 60H  26/0600Z 27.5N  98.5W   40 KT  45 MPH - Tropical Storm (ENE Realitos, Texas)
 72H  26/1800Z 27.3N 100.0W   30 KT  35 MPH - Low (ESE Podrido, Mexico)
 96H  27/1800Z 27.0N 102.0W   20 KT  25 MPH - Low (ESE Ocampo, Texas)
120H  28/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1000 AM CDT Thu Jul 23, 2020

Satellite imagery indicates that the depression is getting better organized, with a better-defined center located near the northeastern end of a broadly curved convective band. Satellite intensity estimates from TAFB and SAB have increased to 30 kt, and that will be the initial intensity for this advisory. An Air Force Reserve Hurricane Hunter aircraft is currently enroute to investigate the depression.

The initial motion is west-northwestward or 285/8 kt. A mid-level ridge over the central United States is the predominant steering influence, and the global models forecast this ridge to build during the several days. This should cause the depression to turn more westward by 48-60 h and south of west after about 72 h. The track guidance is in good agreement with that scenario, and the new NHC forecast track, which has only minor adjustments from the previous track, lies near the various consensus models. The new forecast track has the center making landfall along the Texas coast between 48-60 h.

The depression is in an environment of light shear and over warm sea surface temperatures, so at least slow strengthening is expected until landfall. The new intensity forecast, which lies a little below the intensity consensus, now calls for a peak intensity of 45 kt before landfall. Data from the Hurricane Hunter will give more details on whether the structure of the cyclone has improved or not, which will be incorporated into the next forecast cycle.

Key Messages

  • 1. The depression is expected to strengthen and it could bring tropical-storm-force winds to portions of the Texas coast, where a tropical storm watch is in effect.
  • 2. The depression is expected to produce heavy rains along the Gulf Coast from Louisiana to the Lower Texas Coast. These rains could result in flash flooding and minor river flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 26.3N  90.7W   30 KT  35 MPH - Depression (ESE Port Eads, LA)
 12H  24/0000Z 26.7N  91.8W   30 KT  35 MPH - Depression (ESE Galveston, TX)
 24H  24/1200Z 27.4N  93.4W   35 KT  40 MPH - Tropical Storm (ESE Galveston, TX)
 36H  25/0000Z 27.8N  94.9W   40 KT  45 MPH - Tropical Storm (ENE Corpus Christi, TX)
 48H  25/1200Z 28.0N  96.5W   45 KT  50 MPH - Tropical Storm (ESE San José Island, TX)
 60H  26/0000Z 28.0N  98.0W   40 KT  45 MPH - Tropical Storm (WNW Westdale, TX)
 72H  26/1200Z 27.9N  99.3W   30 KT  35 MPH - Depression (ESE Encinal, TX)
 96H  27/1200Z 27.5N 101.0W   20 KT  25 MPH - Low (WSW Del Lodo, Mexico)
120H  28/1200Z 27.0N 103.0W   15 KT  15 MPH - Low (ESE Laguna del Rey, Mexico)

NWS National Hurricane Center Miami FL 1000 PM CDT Wed Jul 22, 2020

Surface observations and data from the Air Force Hurricane Hunters indicate that the area of low pressure over the central Gulf of Mexico has developed a closed circulation and a well-defined center. In addition, recent satellite images show an area of deep convection expanding over the center. Based on those observations, advisories are being initiated on Tropical Depression Eight. The initial intensity is set at 25 kt based on the earlier reconnaissance data.

The initial motion is an uncertain west-northwestward at 5 kt. A subtropical ridge to the northeast of the depression should cause it to continue moving in that general direction through Friday as it tracks across the northwestern Gulf of Mexico. A slight turn to the left is expected Friday night and Saturday as a ridge builds to the north of the system, taking the center of cyclone across the Texas coast and then inland over southern Texas. The models are in fairly good agreement on this scenario, and the NHC track forecast lies near the various consensus models.

The depression is expected to be in generally light to moderate wind shear conditions, in a fairly moist environment, and over the warm waters of the Gulf of Mexico for the next couple of days, so some strengthening seems likely. However, since the depression is still in its formative stage, the rate of strengthening should be gradual. After the storm crosses the coast, steady weakening should commence. The NHC intensity forecast generally follows the IVCN and HCCA guidance.

Key Messages

  • 1. The depression is expected to strengthen and it could bring tropical-storm-force winds to portions of the Texas coast, where a tropical storm watch has been issued.
  • 2. The depression is expected to produce heavy rains across portions of Louisiana and southern Texas. These rains could result in flash flooding.
FORECAST POSITIONS AND MAX WINDS

INIT  23/0300Z 25.9N  88.2W   25 KT  30 MPH - Depression (ESE Port Eads, LA)
 12H  23/1200Z 26.3N  89.3W   30 KT  35 MPH - Depression (ESE Port Eads, LA)
 24H  24/0000Z 27.0N  90.8W   30 KT  35 MPH - Depression (WSW Cocodrie, LA)
 36H  24/1200Z 27.9N  92.4W   35 KT  40 MPH - Tropical Storm (WSW Galveston, TX)
 48H  25/0000Z 28.2N  94.0W   35 KT  40 MPH - Tropical Storm (WSW Galveston, TX)
 60H  25/1200Z 28.5N  95.3W   40 KT  45 MPH - Tropical Storm (WSW Freeport, TX)
 72H  26/0000Z 28.7N  96.8W   35 KT  40 MPH - Tropical Storm (ENE Placedo, TX)
 96H  27/0000Z 28.8N  98.1W   25 KT  30 MPH - Low (ENE Fashing, TX)
120H  28/0000Z 28.7N 100.5W   20 KT  25 MPH - Low (ESE Eagle Pass, TX)

NWS National Hurricane Center Miami FL 800 PM EDT Wed Jul 22, 2020 

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

The National Hurricane Center is issuing advisories on Tropical Storm Gonzalo, located over the central tropical Atlantic.

1. Data from the Air Force Hurricane Hunters and surface observations indicate that an area of low pressure over the central Gulf of Mexico is gradually becoming better defined. However, the accompanying shower and thunderstorm activity is still poorly organized. Environmental conditions appear conducive for slow development of this system, and a tropical depression is likely to form during the next day or so as it moves west-northwestward at about 10 mph. Interests in the western Gulf of Mexico should monitor the progress of this system, as watches or warnings could be required for portions of the coasts of Texas and Louisiana tonight or on Thursday. * Formation chance through 48 hours…high…80 percent

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