Tropical Storm Genevieve

Post Tropical Genevieve Track 1400 Hours August 21 2020
Post Tropical Genevieve Track 1400 Hours August 21 2020

Genevieve Wind Speed FieldTropical Storm GenevieveNWS National Hurricane Center Miami FL 200 PM PDT Fri Aug 21, 2020 (see video below)

Cool waters and less favorable thermodynamic conditions have continued to take a toll on Genevieve. The system has not had any deep convection for more than 12 hours, and it is unlikely that any organized deep convection will return. As a result, Genevieve has become a post-tropical cyclone and this will be the final NHC advisory on this system. The initial wind speed is set at 35 kt, which is in agreement with recent scatterometer data. The post-tropical cyclone should continue to gradually weaken over cooler water during the next couple of days, and the global model guidance indicates that the circulation will become an open trough within 72 hours.

The cyclone continues to move northwestward at about 10 kt. A northwestward motion is forecast to continue over the next couple of days, but the forward speed of the system is expected to slow as it becomes increasing shallow and is steered by the weaker low-level flow. The track guidance remains tightly clustered and the new foreast is an extension of the previous advisory.

This is the final NHC advisory on Genevieve.

ORECAST POSITIONS AND MAX WINDS

INIT  21/2100Z 25.8N 115.5W   35 KT  40 MPH - Post Tropical (WSW san Carlos, MX)
 12H  22/0600Z 27.0N 117.0W   25 KT  30 MPH - Low (WSW Bahia Tortugas, MX)
 24H  22/1800Z 28.3N 119.1W   25 KT  30 MPH - Low (WSW CMIG, Mexico)
 36H  23/0600Z 29.2N 120.7W   20 KT  25 MPH - Low (WNW CMIG, Mexico)
 48H  23/1800Z 30.2N 121.9W   15 KT  15 MPH - Low (WSW Ensenada, MX)
 60H  24/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 900 AM MDT Fri Aug 21, 2020

Genevieve continues to gradually weaken while it encounters cooler waters and light to moderate southerly shear. Deep convection associated with the system dissipated around the time of the previous advisory, and the cyclone is now comprised of a swirl of low- to mid-level clouds. The initial intensity has been reduced to 40 kt, which is a blend of the latest TAFB Dvorak T- and CI-numbers. Genevieve is expected to continue to gradually weaken today as it moves over SSTs of 24-25 degrees Celsius. It is unlikely that organized deep convection will return, and Genevieve is expected to become a post-tropical cyclone later today. The cyclone’s winds are forecast to drop below tropical storm strength within 12 hours, and the remnant low should continue to spin down over cooler waters west of the Baja California peninsula during the next couple of days. The global models indicate that the remnant low will dissipate in about 72 hours.

Genevieve is moving northwestward at about 9 kt. The cyclone should continue on this general heading over the next couple of days as it moves around the southwestern side of a mid-level ridge over northern Mexico. The remnant low is forecast to decelerate by Sunday as it becomes vertically shallow and is steered by the weaker low-level flow. Large swells from Genevieve that are spreading northward along portions of the west coast of the Baja California peninsula will gradually subside on Saturday.

FORECAST POSITIONS AND MAX WINDS

INIT  21/1500Z 25.0N 114.8W   40 KT  45 MPH - Tropical Storm (WSW san Carlos, Mexico)
 12H  22/0000Z 26.1N 116.2W   30 KT  35 MPH - Low (WSW San Juanico, Mexico)
 24H  22/1200Z 27.6N 118.3W   25 KT  30 MPH - Low (WSW Bahia Tortugas, Mexico )
 36H  23/0000Z 28.7N 120.2W   20 KT  25 MPH - Low (WSW CMIG, Mexico)
 48H  23/1200Z 29.5N 121.6W   20 KT  25 MPH - Low (WNW CMIG, Mexico)
 60H  24/0000Z 30.3N 122.3W   15 KT  15 MPH - Low (WSW Ensenada, Mexico)
 72H  24/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 900 PM MDT Thu Aug 20, 2020

Genevieve continues to gradually weaken. Recent microwave images indicate that the storm has become quite asymmetric with the low-level center located on the southern edge of the main area of deep convection. The decay in the structure of the storm appears to be the result of a combination of southerly wind shear and dry air that has wrapped into that portion of the circulation. The initial intensity is lowered to 55 kt, which is near the higher end of the satellite intensity estimates. Surface observations from the southwestern coast of the Baja California Sur indicate that the storm is still producing tropical-storm-force winds there.

Genevieve has moved a little to the left recently, but a longer term motion is northwestward at 9 kt. The weakening storm should continue to move generally northwestward during the next few days at roughly the same forward speed as it remains steered by a low- to mid-level ridge centered over the southwestern United States. This track should take the storm gradually away from the Baja California coast. The NHC track forecast lies very near the multi-model consensus aids TVCE and HCCA.

Continued weakening is expected due to a combination of increasingly southerly wind shear, dry air, and progressively cooler SSTs. Genevieve is likely to weaken to a tropical depression in a day or so, and it is forecast to degenerate to a remnant low in 36 to 48 hours. The NHC intensity forecast lies near the middle of the guidance envelope.

Key Messages:

  • 1. Tropical storm conditions are expected to continue for a few more hours over the southwestern coast of the Baja California peninsula.
  • 2. Large swells generated by Genevieve will continue to affect the coast of the southern and central Baja California peninsula through Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  21/0300Z 24.2N 113.2W   55 KT  65 MPH - Tropical Storm (WSW Adolfo L Mateos, Mexico)
 12H  21/1200Z 25.1N 114.4W   45 KT  50 MPH - Tropical Storm (WNW CMIG, Mexico)
 24H  22/0000Z 26.4N 116.1W   35 KT  40 MPH - Tropical Storm (WSW Bahía Asunción, Mexico)
 36H  22/1200Z 27.8N 118.2W   30 KT  35 MPH - Depression (WSW Bahia Tortugas, Mexico)
 48H  23/0000Z 29.0N 120.2W   25 KT  30 MPH - Low (WNW CMIG, Mexico)
 60H  23/1200Z 29.7N 121.6W   25 KT  30 MPH - Low (WSW Tiajuana, Mexico)
 72H  24/0000Z 30.5N 122.5W   20 KT  25 MPH - Low (WSW Tiajuana, Mexico)
 96H  25/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 300 PM MDT Thu Aug 20, 2020

Dry and stable air continues to be drawn into Genevieve’s circulation. This is noted by a slow erosion of convection over the southwestern semicircle, and warming cloud tops over the past several hours, indicating weakening. An Air Force Reserve Hurricane Hunter aircraft investigating the system this afternoon measured peak 700 mb flight-level winds of 71 kt, which reduce to 64 kt at the surface, with peak SFMR winds of 57 kt. A blend of these values supports lowering the initial intensity to 60 kt.

Genevieve should continue to gradually weaken as it moves over progressively lower oceanic temperatures. By Friday, the cyclone is expected to cross the 26 C SST isotherm, and it will reach waters cooler than 24 C by early Saturday. These much cooler waters should cause the cyclone to degenerate to a remnant low by late Saturday. The latest NHC intensity forecast is little changed from the previous one, and is near the HFIP corrected consensus HCCA.

Genevieve continues to move northwestward at 10 kt, paralleling the coast of the southern Baja California Peninsula. This general motion is expected to continue until the cyclone dissipates later in the forecast period. On this track, Genevieve will begin to move away from the peninsula tonight. The NHC forecast track is very little changed from the previous one and is in the middle of the tightly clustered track guidance.

Key Messages:

  • 1. The center of Genevieve is forecast to pass just west of the Baja California peninsula through this evening, with tropical storm conditions expected to continue over portions of this area during this time.
  • 2. Rainfall from Genevieve will continue to decrease in intensity over southern Baja California Sur, although some instances of flash flooding and mudslides remain possible through this evening.
  • 3. Large swells generated by Genevieve will affect portions of the west-central coast of Mexico and the coast of the southern Baja California peninsula through Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 23.9N 112.4W   60 KT  70 MPH - Tropical Storm (WSW San Carlos, Mexico)
 12H  21/0600Z 24.8N 113.7W   50 KT  60 MPH - Tropical Storm (WSW Adolfo L Mateos, Mexico)
 24H  21/1800Z 26.1N 115.3W   40 KT  45 MPH - Tropical Storm (WSW Punta Abrejos, Mexico)
 36H  22/0600Z 27.4N 117.2W   30 KT  35 MPH - Depression (WSW Bahia Tortugas, Mexico)
 48H  22/1800Z 28.6N 119.3W   25 KT  30 MPH - Low (WSW CMIG, Mexico)
 60H  23/0600Z 29.4N 120.9W   25 KT  30 MPH - Low (WNW Ensenada, Mexico)
 72H  23/1800Z 30.3N 122.0W   20 KT  25 MPH - Low (WSW Ensenada, Mexico)
 96H  24/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 900 AM MDT Thu Aug 20, 2020 

Genevieve’s overall satellite appearance continues to slowly degrade, with a shrinking central dense overcast and dry, stable air being drawn into the eastern portion of the circulation. The Dvorak data-T numbers from TAFB, SAB, and the UW-CIMSS ADT have decreased to 3.5. However, since the CI numbers from these respective analyses are 4.5, the initial intensity of 65 kt will be based off a blend of those two values. Genevieve is forecast to move over gradually cooler waters during the next 24 h, so a slow weakening trend is expected to continue through that time. Beyond 24 h, the cyclone will cross the 26C SST isotherm and reach temperatures below 24C after 48 h. This should result in a faster rate of weakening, and the cyclone is expected to degenerate into a remnant low by 60 h. The latest NHC intensity forecast is essentially an update of the previous one, and is near the HFIP corrected consensus HCCA. Genevieve has made its anticipated turn toward the northwest and has accelerated slightly to 10 kt. This general motion is expected to continue until the cyclone dissipates later in the forecast period. On this track, Genevieve will move parallel to the coast of the southern Baja California peninsula today and then begin to move away from the peninsula late tonight. The NHC forecast track is very little changed from the previous one, with the only notable difference being a slightly faster forward speed. This forecast is very near the tightly clustered track guidance.

Key Messages:

  • 1. The center of Genevieve is forecast to pass just west of the Baja California peninsula today. Tropical storm conditions will continue over southern Baja California Sur through today, and possibly linger into tonight.
  • 2. Continued heavy rainfall from Genevieve may lead to life- threatening flash flooding and mudslides across portions of far southern Baja California Sur through today.
  • 3. Large swells generated by Genevieve will affect portions of the west-central coast of Mexico and the coast of the southern Baja California peninsula through Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  20/1500Z 23.3N 111.4W   65 KT  75 MPH - Category 1 (WSW Todas Santos, Mexico)
 12H  21/0000Z 24.1N 112.5W   60 KT  70 MPH - Tropical Storm (WSW San Carlos, Mexico)
 24H  21/1200Z 25.3N 114.1W   50 KT  60 MPH - Tropical Storm (WSW Adolfo L Mateos, Mexico)
 36H  22/0000Z 26.6N 115.8W   40 KT  45 MPH - Tropical Storm (WSW Punta Abrejos, Mexico)
 48H  22/1200Z 27.8N 117.8W   30 KT  35 MPH - Depression (WSW Bahia Tortugas, Mexico)
 60H  23/0000Z 28.8N 119.8W   25 KT  30 MPH - Low (WSW CMIG, Mexico)
 72H  23/1200Z 29.7N 121.4W   25 KT  30 MPH - Low (WNW CMIG, Mexico)
 96H  24/1200Z 31.1N 122.5W   20 KT  25 MPH - Low (WSW Tijuana, Mexico)
120H  25/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 900 PM MDT Wed Aug 19, 2020

Genevieve’s infrared satellite presentation has continued to become less defined since the previous advisory, with microwave imagery indicating that the eyewall has completely eroded in the southern semicircle. Satellite intensity estimates have decreased as a result, with TAFB and SAB now assessing intensity estimates of T4.5/77 kt. Therefore, the initial intensity has been lowered to 75 kt.

Genevieve has made a slight right-of-track jog, and the initial motion estimate is now 345/06 kt. The recent north-northwestward motion is expected to be temporary and is likely due to the outer circulation interacting with the mountainous terrain of Baja California Sur. However, the global and regional models remain in good agreement that the deep-layer subtropical ridge to the north of the hurricane is expected to turn Genevieve back toward the northwest by early Thursday. That motion is then forecast to continue through the end of the 5-day forecast period. On this track, the center of Genevieve will pass just to the southwest or west of the southern portion of the Baja California peninsula overnight and on Thursday. The new NHC track forecast is a little to the right or east of the previous advisory track through 24 hours to account for the recent northward jog. Thereafter, the new forecast track is similar to the previous advisory and lies near the eastern edge of the model guidance suite.

Genevieve will continue to move over gradually decreasing sea surface temperatures (SSTs) and shallower warm waters over the next day or so, which will produce cold upwelling, resulting in slow weakening during the next 24-36 hours. Thereafter, the cyclone will be moving over sub-25 deg C SSTs, which will induce a faster rate of weakening, with Genevieve forest to degenerate into a post-tropical remnant low by 72 hours. The official intensity forecast is similar to the IVCN simple consensus aid, due to the low vertical shear conditions that are expected to persist through 36-48 hours, and is above the NOAA-HCCA corrected-consensus model.

Key Messages:

  • 1. The center of Genevieve is forecast to pass just west of the Baja California peninsula tonight and Thursday. Tropical storm conditions are expected to spread across southern Baja California Sur through Thursday. Hurricane conditions are expected within the Hurricane Warning area tonight and continuing into Thursday.
  • 2. Heavy rainfall from Genevieve may lead to life-threatening flash flooding and mudslides across portions of far southern Baja California Sur through Thursday.
  • 3. Large swells generated by Genevieve will affect portions of the west-central coast Mexico and the coast of the southern Baja California peninsula through Friday.
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0300Z 22.0N 110.1W   75 KT  85 MPH - Category 1 (WSW Cabo San Lucas, Mexico)
 12H  20/1200Z 22.8N 110.8W   70 KT  80 MPH - Category 1 (WSW Cabo San Lucas, Mexico)
 24H  21/0000Z 23.6N 112.1W   65 KT  75 MPH - Category 1 (WSW Cabo San Lucas, Mexico)
 36H  21/1200Z 24.5N 113.5W   60 KT  70 MPH - Tropical Storm (WNW San Carlos, Mexico)
 48H  22/0000Z 25.7N 115.3W   50 KT  60 MPH - Tropical Storm (WSW Punta Abreojos, Mexico)
 60H  22/1200Z 26.8N 117.1W   40 KT  45 MPH - Tropical Storm (WSW Bahía Asunción, Mexico)
 72H  23/0000Z 28.0N 119.0W   30 KT  35 MPH - Low (WSW CMIG, Mexico)
 96H  24/0000Z 29.5N 121.1W   25 KT  30 MPH - Low (WSW Ensenada, Mexico)
120H  25/0000Z 31.1N 121.9W   20 KT  25 MPH - Low (WSW Tijuana, Mexico)

NWS National Hurricane Center Miami FL 300 PM MDT Wed Aug 19, 2020 

Genevieve’s satellite presentation has continued to degrade this afternoon with the eye becoming less distinct in visible imagery and a warming of the cloud tops in the surrounding ring of convection. Objective and subjective Dvorak T-numbers have continued to fall, and the reduction in wind speed has been confirmed by recent data from an Air Force Reserve reconnaissance aircraft that has provided a couple of center fixes during its mission this afternoon. Somewhat surprisingly, the plane only reported peak flight-level winds of 82 kt and SFMR winds of 69 kt. The latest minimum pressure reported by the aircraft was 974 mb. Since the aircraft only flew a single alpha pattern, it is possible that the strongest winds were not captured. Therefore the initial intensity has been conservatively adjusted to 80 kt.

The hurricane will be moving over gradually decreasing sea surface temperatures over the next day or so, but only gradual weakening expected during this time. Once Genevieve begins to move away from the Baja California peninsula, it will be moving over much cooler waters, and a slightly faster rate of weakening is expected, with the system degenerating into a remnant low by 96 hours. The new NHC intensity forecast is in best agreement with the SHIPS statistical guidance for the first day or two, and then trends closer the intensity consensus aids thereafter.

Genevieve is moving north-northwestward or 330/7 kt. Mid-level ridging to the north of the system is expected to cause the hurricane to turn northwestward tonight, and a northwestward motion should then continue over the next several days. On this track, the center of Genevieve will pass near or just southwest of the southern portion of the Baja California peninsula overnight and on Thursday. The recent eastward shift in the guidance did not continue in the 1200 UTC models, so little overall change was required from the previous NHC track foreast. The updated forecast is near the middle of the guidance envelope not far form the multi-model consensus aids.

Key Messages:

  • 1. The center of Genevieve is forecast to pass near or just west of the Baja California peninsula tonight and Thursday. Tropical storm conditions are expected to spread across southern Baja California Sur through Thursday. Hurricane conditions are expected within the Hurricane Warning area beginning tonight and continuing into Thursday.
  • 2. Heavy rainfall from Genevieve may lead to life-threatening flash flooding and mudslides across portions of far southern Baja California Sur through Thursday.
  • 3. Large swells generated by Genevieve will affecting portions of the west-central coast Mexico and the coast of the southern Baja California peninsula through Friday.
FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 21.4N 110.1W   80 KT  90 MPH - Category 1 (WSW Cabo San Lucas, Mexico)
 12H  20/0600Z 22.2N 110.6W   80 KT  90 MPH - Category 1 (WSW Cabo San Lucas, Mexico)
 24H  20/1800Z 23.1N 111.7W   75 KT  85 MPH - Category 1 (WNW Cabo San Lucas, Mexico)
 36H  21/0600Z 23.9N 113.0W   70 KT  80 MPH - Category 1 (WSW Puerto Cortes, Mexico)
 48H  21/1800Z 24.8N 114.5W   60 KT  70 MPH - Tropical Storm (WNW San Carlos, Mexico)
 60H  22/0600Z 26.0N 116.3W   50 KT  60 MPH - Tropical Storm (WSW Punta Abreojos, Mexico)
 72H  22/1800Z 27.1N 118.2W   40 KT  45 MPH - Tropical Storm (WSW Bahía Asunción, Mexico)
 96H  23/1800Z 29.1N 121.3W   25 KT  30 MPH - Low (WSW CMIG, Mexico)
120H  24/1800Z 30.5N 122.0W   20 KT  25 MPH - Low (WSW Ensenada, Mexico)

NWS National Hurricane Center Miami FL 900 AM MDT Wed Aug 19, 2020

Genevieve continues to have a fairly well-defined eye in geostationary satellite imagery, however a recent SSMIS microwave overpass shows that the eyewall is open to the southwest and that deep convection is generally lacking over the southwestern portion of the circulation. The various satellite intensity estimates range from about 80-96 kt, which SATCON being at the higher end. The cloud tops over the northeastern portion of the circulation have cooled within the past few hours, so the initial intensity is held at a possibly generous 100 kt. An Air Force Reserve hurricane hunter aircraft is scheduled to investigate Genevieve this afternoon, and should provide a better assessment of the hurricane’s intensity and size.

The hurricane has continued to move slightly right of track, and the initial motion estimate is 335/8 kt. A north-northwestward motion is expected to continue today, followed by a turn toward the northwest tonight as mid-level ridging builds over northwestern Mexico. The new NHC forecast track has again been shifted slightly east of the previous track at 12 and 24 hours, but it is essentially unchanged thereafter. This track adjustment brings the center a little closer to the southern portion of the Baja California peninsula tonight and early Thursday. Only a slight deviation to the right of the track would bring hurricane-force winds onshore, and the government of Mexico has issued a Hurricane Warning for a portion of the southern coast of Baja California.

Genevieve is forecast to move over gradually decreasing sea surface temperatures over the next couple of days, which should result in slow weakening during that time. After 48 hours, the cyclone will encounter much cooler waters and a more stable air mass. Therefore, a more rapid rate of weakening is expected after that time, with the system becoming a remnant low by 96 hours. The NHC intensity forecast is a blend of the statistical and dynamic model guidance.

Key Messages:

  • 1. The center of Genevieve is forecast to pass near or just west of the Baja California peninsula. Tropical storm conditions are expected to spread across southern Baja California Sur this afternoon and continuing through Thursday. Hurricane conditions are expected within the Hurricane Warning area beginning tonight and continuing into Thursday.
  • 2. Heavy rainfall from Genevieve may lead to life-threatening flash flooding and mudslides across portions of far southern Baja California Sur through Thursday.
  • 3. Large swells generated by Genevieve are affecting portions of the coast of southern Mexico and will spread northward along the coast of Mexico to the Baja California peninsula through Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  19/1500Z 20.9N 109.7W  100 KT 115 MPH - Category 3 (WSW Puerto Vallarta, Mexico)
 12H  20/0000Z 21.7N 110.2W   90 KT 105 MPH - Category 2 (WSW Cabo San Lucas, Mexico)
 24H  20/1200Z 22.6N 111.1W   85 KT 100 MPH - Category 2 (WSW Cabo San Lucas, Mexico)
 36H  21/0000Z 23.4N 112.3W   80 KT  90 MPH - Category 1 (WNW Todos Santos, Mexico)
 48H  21/1200Z 24.3N 113.6W   75 KT  85 MPH - Category 1 (WSW San Carlos, Mexico)
 60H  22/0000Z 25.5N 115.4W   60 KT  70 MPH - Tropical Storm (WSW Punta Abreojos, Mexico)
 72H  22/1200Z 26.6N 117.2W   50 KT  60 MPH - Tropical storm (WSW Bahía Asunción, Mexico)
 96H  23/1200Z 28.9N 120.6W   30 KT  35 MPH - Low (WSW CMIG, Mexico)
120H  24/1200Z 30.5N 122.5W   20 KT  25 MPH - Low (WSW Tijuana, Mexico)

NWS National Hurricane Center Miami FL 300 AM MDT Wed Aug 19, 2020 

Genevieve continues to have a well-defined eye embedded in a central dense overcast with cloud tops temperatures to about -65C. The various objective and subjective satellite intensity estimates have trended down since the last advisory, and the initial intensity is reduced to a possibly generous 100 kt. Infrared imagery hints that the hurricane may be undergoing an eyewall replacement cycle. However, there are no recent microwave data to confirm this.

Genevieve continues to move a little more northward than previously expected, with the initial motion now north-northwest or 335/9 kt. Mid-level ridging to the north and northeast of the hurricane should cause a turn toward the northwest during the next 12-24 h, with this motion continuing through the balance of the forecast period. The guidance has shifted a little to the east since the last advisory, and the new NHC forecast track has been shifted to the east of the previous track through 72 h. The new track keeps the center offshore of the Baja California peninsula by 50-60 n mi.

The forecast track takes the center of Genevieve over steadily decreasing sea surface temperatures, especially after 12 h. This should cause rapid weakening to begin later today or tonight. The new NHC intensity forecast shows little change in strength during the first 12 h due to the chance the hurricane may undergoing an eyewall replacement. After that time, the forecast follows the rapid weakening trend of the previous forecast, with Genevieve likely to become post-tropical by 96 h and a remnant low by 120 h. The new forecast continues to lie above the intensity consensus.

The current forecast track requires a hurricane watch for portions of the southern Baja California peninsula at this time. A hurricane warning may be needed if succeeding forecast tracks trend closer to the peninsula.

Key Messages:

  • 1. The center of Genevieve is forecast to move just west of the Baja California peninsula. However, the forecast track is now close enough to southern Baja California Sur that a Hurricane Watch has been issued. Tropical storm conditions should spread across southern Baja California Sur beginning this afternoon and continuing through Thursday,
  • 2. Large swells generated by Genevieve are affecting portions of the coast of southern Mexico and will spread northward along the coast of Mexico to the Baja California peninsula through Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  19/0900Z 20.2N 109.4W  100 KT 115 MPH - Category 3 (WSW Puerto Vallarta, Mexico)
 12H  19/1800Z 21.1N 109.9W  100 KT 115 MPH - Category 3 (WSW Cabo San Lucas, Mexico)
 24H  20/0600Z 22.1N 110.7W   90 KT 105 MPH - Category 2 (WSW Cabo San Lucas, Mexico)
 36H  20/1800Z 22.9N 111.6W   85 KT 100 MPH - Category 2 (WSW Cabo San Lucas, Mexico)
 48H  21/0600Z 23.7N 112.7W   75 KT  85 MPH - Category 1 (WNW Todos Santos, Mexico)
 60H  21/1800Z 24.7N 114.2W   65 KT  75 MPH - Category 1 (WSW San Carlos, Mexico)
 72H  22/0600Z 25.8N 116.1W   55 KT  65 MPH - Tropical Storm (WSW Punta Abreojos, Mexico)
 96H  23/0600Z 28.0N 119.5W   35 KT  40 MPH - Low (WSW CMIG, Mexico)
120H  24/0600Z 30.0N 122.0W   20 KT  25 MPH - Low (WSW Tijuana, Mexico)

NWS National Hurricane Center Miami FL 900 PM MDT Tue Aug 18, 2020

While Genevieve continues to have a distinct eye on satellite images, the inner-core convection has weakened during the past several hours, although there is little evidence of any eyewall replacement cycle starting. The majority of the satellite estimates range from 100 to 110 kt, and a blend of these values gives an initial wind speed of 105 kt.

My strong suspicion is that the hurricane has weakened today due to it encountering cooler SSTs from the wake of Hurricane Elida (from last week), and these waters will likely help limit any near-term chance of strengthening. While Genevieve should move north of the wake tomorrow, its slow movement and fairly large size could help to maintain upwelling and cooler waters near the core. In a couple of days, quickly falling SSTs should cause rapid weakening, and Genevieve is forecast to be a non-convective low in 4 days over waters near 23C. The new forecast is lower than the previous one, but it is still above the model consensus at most times before 48 hours.

The hurricane has turned to the right tonight, with the latest initial motion estimated to be 325/9 kt. A slightly slower northwestward to north-northwestward motion is expected during the next day or so due to steering from a distant ridge over central Mexico, taking the core of the hurricane near but just west of the southern Baja California peninsula during that time. Similar to the previous cycle, the models have shifted closer to the Baja California Sur coast but still about 60 n mi offshore, and the NHC forecast is adjusted in that direction. Thereafter, a mid-level ridge over the southwestern United States should cause Genevieve to turn more toward the west-northwest or northwest, away from the Baja coast. A small eastward trend is noted at long range as well, and the official forecast follows that lead.

Key Messages:

  • 1. The center of Genevieve is forecast to move just west of the Baja California peninsula, but it is still expected to cause tropical storm conditions across portions of southern Baja California Sur. These conditions are expected to begin Wednesday afternoon and could spread northwestward through Thursday.
  • 2. Large swells generated by Genevieve are affecting portions of the coast of southern Mexico and will spread northward along the coast of Mexico to the Baja California peninsula through Thursday.
FORECAST POSITIONS AND MAX WINDS

INIT  19/0300Z 19.5N 109.0W  105 KT 120 MPH - Category 3 (WSW Puerto Vallarta, Mexico)
 12H  19/1200Z 20.5N 109.7W  105 KT 120 MPH - Category 3 (WSW Cabo San Lucas, Mexico)
 24H  20/0000Z 21.5N 110.4W  100 KT 115 MPH - Category 3 (WSW Cabo San Lucas, Mexico)
 36H  20/1200Z 22.4N 111.3W   90 KT 105 MPH - Category 2 (WSW Cabo San Lucas, Mexico)
 48H  21/0000Z 23.1N 112.3W   75 KT  85 MPH - Category 1 (WNW Cabo San Lucas, Mexico)
 60H  21/1200Z 24.0N 113.6W   65 KT  75 MPH - Category 1 (WSW San Carlos, Mexico)
 72H  22/0000Z 25.1N 115.2W   55 KT  65 MPH - Tropical Storm (WSW AL Mateos, Mexico)
 96H  23/0000Z 27.5N 118.7W   40 KT  45 MPH - Low (WSW CMIG, Mexico)
120H  24/0000Z 29.5N 121.5W   25 KT  30 MPH - Low (WSW CMIG, Mexico)

NWS Weather Prediction Center College Park MD 300 PM MDT Tue Aug 18, 2020

Genevieve remains an impressive hurricane. Geostationary satellite and microwave images show a well organized inner core with a nearly circular eye and pronounced outer bands in most quadrants. However, just recently, there has been evidence of a few dry slots forming between the inner core and outer bands. An average of the latest subjective and objective satellite intensity estimates supports holding the initial intensity steady at 115 kt.

The hurricane still has another day or so over warm SSTs and in favorable atmospheric conditions, so Genevieve should maintain its intensity or perhaps strengthen a little during that time period. After that time, however, progressively cooler waters, drier air, and an increase in wind shear should cause a rapid decay of the cyclone. Genevieve will likely become post-tropical in 4 to 5 days when it is expected to be over SSTs of 22-23 C. The NHC intensity forecast lies near the high end of the guidance for the first day or so, and then falls in line with the various consensus aids after that.

Genevieve is moving a little slower to the northwest, with the latest initial motion estimated to be 310/10 kt. A slightly slower northwestward motion is expected during the next day or so, taking the core of the hurricane just west of the southern Baja California peninsula during that time. The models have shifted to the right this cycle, closer to the Baja coast, and the NHC forecast follows this trend. Thereafter, a building mid-level ridge should cause Genevieve to turn slightly to the left, away from the Baja coast. Due to the eastward shift in the track forecast, the government of Mexico has extended the Tropical Storm Warning and Watch northward on the west coast of the Baja California peninsula.

Key Messages:

  • 1. The center of Genevieve is forecast to move just west of the Baja California peninsula, but it is still expected to cause tropical storm conditions across portions of southern Baja California Sur. These conditions are expected to begin Wednesday afternoon and could spread northwestward through Thursday.
  • 2. Large swells generated by Genevieve are affecting portions of the coast of southern Mexico and will spread northward along the coast of Mexico to the Baja California peninsula by Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 18.7N 108.7W  115 KT 130 MPH - Category 4 (WSW Manazillo, Mexico)
 12H  19/0600Z 19.7N 109.6W  120 KT 140 MPH - Category 4 (WSW Manazillo, Mexico)
 24H  19/1800Z 20.9N 110.4W  115 KT 130 MPH - Category 4 (WSW Puerto Vallarta, Mexico)
 36H  20/0600Z 21.8N 111.3W   95 KT 110 MPH - Category 2 (WSW Cabo San Lucas, Mexico)
 48H  20/1800Z 22.7N 112.4W   80 KT  90 MPH - Category 1 (WNW Cabo San Lucas, Mexico)
 60H  21/0600Z 23.4N 113.6W   70 KT  80 MPH - Category 1 (WSW Todas Santos, Mexico)
 72H  21/1800Z 24.4N 115.1W   60 KT  70 MPH - Tropical Storm (WNW San Carlos, Mexico)
 96H  22/1800Z 26.6N 118.4W   45 KT  50 MPH - Tropical Storm (WSW Bahía Asunción, Mexico)
120H  23/1800Z 28.9N 121.5W   30 KT  35 MPH - Low (WSW CMIG, Mexico)

NWS National Hurricane Center Miami FL 900 AM MDT Tue Aug 18, 2020

Since the issuance of the last advisory, Genevieve has continued to rapidly intensify. The major hurricane has a very well-defined and clear eye and microwave imagery as recent as 12Z did not show any indication of a secondary eyewall. Objective intensity estimates from the UW-CIMSS SATCON were as high as 124 kt earlier this morning, but subjective Dvorak estimates at 12Z were a little lower due to the formation of a small break in the cold cloud tops surrounding Genevieve’s eye. Even then, a blend of all available intensity estimates still supports an intensity of 115 kt for this advisory.

Additional rapid strengthening is possible for at least the next 12 h given the current structure of the hurricane and the extremely favorable environment it is moving through. The NHC forecast is well above the guidance for the next 24 h out of respect for that possibility. It is worth noting that eyewall replacement cycles are generally poorly forecast and the onset of one could bring an abrupt halt to Genevieve’s intensification. By the time Genevieve nears the Baja California peninsula on late Wednesday, rapid weakening is expected as the system moves over cooler waters and encounters an increase in southwesterly shear associated with an upper-level trough to the northwest. Upwelling from the hurricane’s own wind field and decreasing forward speed could also bring about weakening. By the end of the weak Genevieve will likely weaken to a tropical storm and then become a remnant low.

The hurricane is moving slightly slower toward the northwest and a further decrease in forward speed is anticipated for the next day or two. There was no substantial change made to the NHC track forecast, and Genevieve is still predicted to be steered just west of the Baja California peninsula by a deep-layer ridge centered over the southwestern U.S. The track guidance remains tightly clustered, so confidence in the forecast remains fairly high.

Key Messages:

  • 1. The center of Genevieve is forecast to move just west of the Baja California peninsula, but it is still expected to cause tropical storm conditions across portions of southern Baja California Sur. These conditions are expected to begin Wednesday afternoon and could spread northwestward through Thursday.
  • 2. Large swells generated by Genevieve are affecting portions of the coast of southern Mexico and will spread northward along the coast of Mexico to the Baja California peninsula by Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  18/1500Z 18.0N 108.0W  115 KT 130 MPH - Category 4 (WSW Manazillo, Mexico)
 12H  19/0000Z 19.0N 109.3W  130 KT 150 MPH - Category 4 (WSW Manazillo, Mexico)
 24H  19/1200Z 20.2N 110.4W  130 KT 150 MPH - Category 4 (WSW Puerto Vallarta, Mexico)
 36H  20/0000Z 21.3N 111.3W  120 KT 140 MPH - Category 4 (WSW Cabo San Lucas, Mexico)
 48H  20/1200Z 22.2N 112.3W  105 KT 120 MPH - Category 2 (WSW Cabo San Lucas, Mexico)
 60H  21/0000Z 23.2N 113.5W   90 KT 105 MPH - Category 2 (WSW Todas Santos, Mexico)
 72H  21/1200Z 24.1N 115.0W   75 KT  85 MPH - Category 1 (WSW Puerto Cortés, Mexico)
 96H  22/1200Z 26.3N 118.1W   50 KT  60 MPH - Tropical Storm (WSW Bahía Asunción, Mexico)
120H  23/1200Z 28.7N 121.4W   35 KT  40 MPH - Post Tropical (WSW CMIG, Mexico)

NWS National Hurricane Center Miami FL 900 PM MDT Mon Aug 17, 2020

Genevieve’s rapid intensification phase continues, having strengthened 40 kt over the past 24 hours. The upper-level outflow pattern has continued to expand, and outflow channels to the north and south have become evident in water vapor imagery and UW-CIMSS upper-level wind analyses. A 20-nmi-wide, cloud-filled eye has appeared in infrared and visible satellite imagery during the past few hours, indicating that Genevieve’s wind field and vertical structure has improved significantly since the previous advisory. Subjective satellite intensity estimates are T5.0/90 kt from TAFB and T4.5/77 kt from SAB, while objective estimates are T4.7/82 kt from UW-CIMSS ADT and T5.1/92 kt from the NHC. An average of these estimates supports an initial intensity of 85 kt.

Genevieve has remained a well-behaved hurricane and lies on the previous advisory track, maintaining a motion of 300/15 kt. The hurricane is expected to continue moving west-northwestward for the next 12 hours or so while the cyclone skirts the southwestern periphery of a broad deep-layer ridge. A slight motion shift toward the northwest is forecast during the 24-48 hour period, bringing Genevieve’s outer wind field a little closer to Baja California Sur. Thereafter, a motion back toward the west-northwest is forecast, which will keep the center of the hurricane moving parallel to but offshore the west coast of Baja California Sur. The new NHC forecast track is essentially just an extension of the previous advisory track, and lies down the middle of the tightly packed simple and corrected-consensus models.

Genevieve is forecast to continue its rapid intensification phase for the next 36 hours or so while the hurricane moves within an extremely favorable environment characterized by low vertical wind shear less than 5 kt, dual outflow channels, sea-surface temperatures (SSTs) of 29-30C, and a very moist middle-troposphere. By 48 hours, the hurricane will be moving over upper-ocean heat content values of less than 5 units due to shallow warm ocean layer, likely resulting in significant cold upwelling occurring. This should initiate a gradual weakening trend, followed by rapid weakening after 60 hours when Genevieve will be moving over sub-25 deg C water. By 120 hours, the hurricane is expected to degenerate into a convection-free post-tropical cyclone over 21 deg C SSTs. The NHC official intensity forecast remains near the the upper end of the intensity guidance, and is similar to the previous advisory.

Key Messages:

  • 1. There is an increasing risk of tropical-storm-force winds over the southern portion of the Baja California peninsula beginning Wednesday afternoon and continuing into Thursday as Genevieve passes near or southwest of the southern tip of Baja California, and a Tropical Storm Watch is in effect for a portion of this area.
  • 2. Large swells generated by Genevieve are affecting portions of the coast of southern Mexico and will spread northward along the coast of Mexico to the Baja California peninsula by Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  18/0300Z 16.5N 106.0W   85 KT 100 MPH - Category 2 (WSW Acapulco, Mexico)
 12H  18/1200Z 17.5N 107.5W  100 KT 115 MPH - Category 3 (WSW Lázaro Cárdenas, Mexico)
 24H  19/0000Z 18.9N 109.3W  115 KT 130 MPH - Category 4 (ENE Isla Sorroco, Mexico)
 36H  19/1200Z 20.1N 110.5W  120 KT 140 MPH - Category 4 (ENE Isla Sorroco, Mexico)
 48H  20/0000Z 21.2N 111.4W  115 KT 130 MPH - Category 4 (ENE Isla Sorroco, Mexico)
 60H  20/1200Z 22.3N 112.5W  100 KT 115 MPH - Category 3 (WSW Cabo San Lucas, Mexico)
 72H  21/0000Z 23.3N 113.8W   85 KT 100 MPH - Category 2 (WSW Todas Santos, Mexico)
 96H  22/0000Z 25.4N 117.0W   60 KT  70 MPH - Tropical Storm (WSW San Juanico, Mexico)
120H  23/0000Z 27.9N 120.5W   40 KT  45 MPH - Post Tropical (WSW CMIG,  Mexico)

NWS National Hurricane Center Miami FL 400 PM CDT Mon Aug 17, 2020 

Genevieve has continued to rapidly strengthen today, and has been undergoing RI since its formation yesterday morning. One-minute GOES-16 satellite imagery and an earlier GMI microwave overpass has revealed very impressive banding features, along with evidence of a small low-level eye feature. Since the time of that microwave data, banding has continued to increase near the center, and it appears that a banding-type eye may be forming. The various satellite intensity estimates range from 70-80 kt, so the initial wind speed has been raised to 75 kt.

Genevieve remains within a very favorable oceanic and atmospheric environment, and the intensity guidance suggests that rapid strengthening is likely to continue for another day or so. The SHIPS Rapid Intensification Index again shows a greater than 80- percent chance of a 30 kt increase in wind speed over the next 24 hours and about a 60-percent chance of a 40 kt increase over that time period. The NHC intensity forecast continues to call for rapid strengthening and shows Genevieve reaching category 4 strength by late Tuesday. This is in line with the latest SHIPS and HFIP corrected consensus models. After 48 h, the hurricane will be moving over slightly cooler waters and weaken should begin, with a faster rate of weakening expected on days 4 and 5.

The hurricane has moved a bit right of track since yesterday, but the longer term motion is west-northwestward at 16 kt. A strong ridge of high pressure over the western United States should continued to steer Genevieve west-northwestward for another 24 hours. After that time, a slower northwestward motion should commence. There is a bit more spread in the dynamical model guidance with the GFS, its ensemble mean, and the HWRF having shifted slightly eastward. However, the consensus aids have not changed much, and the NHC track is similar to the previous advisory, near the middle of the guidance envelope.

Recent ASCAT data showed that the tropical-storm-force wind field was a little larger than previously estimated over the eastern semicircle of the storm. The initial and forecast wind radii have been adjusted outward accordingly.

Key Messages:

  • 1. There is an increasing risk of tropical-storm-force winds over the southern portion of the Baja California peninsula beginning Wednesday afternoon and continuing into Thursday as Genevieve passes near or southwest of the southern tip of Baja California, and a Tropical Storm Watch has been issued for a portion of this area.
  • 2. Large swells generated by Genevieve are affecting portions of the coast of southern Mexico and will spread northward along the coast of Mexico to the Baja California peninsula by Wednesday.
FORECAST POSITIONS AND MAX WINDS

INIT  17/2100Z 15.5N 104.6W   75 KT  85 MPH - Category 1 (WSW Acapulco, Mexico)
 12H  18/0600Z 16.6N 106.6W   95 KT 110 MPH - Category 2 (WSW Acapulco, Mexico)
 24H  18/1800Z 18.0N 108.5W  110 KT 125 MPH - Category 3 (WSW Lázaro Cárdenas, Mexico)
 36H  19/0600Z 19.3N 109.8W  120 KT 140 MPH - Category 4 (ENE Isla Sorroco, Mexico)
 48H  19/1800Z 20.6N 110.8W  115 KT 130 MPH - Category 4 (ENE Isla Sorroco, Mexico)
 60H  20/0600Z 21.6N 111.6W  105 KT 120 MPH - Category 3 (WSW Cabo San Lucas, Mexico)
 72H  20/1800Z 22.8N 113.1W   90 KT 105 MPH - Category 2 (WNW Cabo San Lucas, Mexico)
 96H  21/1800Z 24.8N 116.0W   60 KT  70 MPH - Tropical Storm (WSW San Juanico, Mexico)
120H  22/1800Z 27.2N 119.7W   45 KT  50 MPH - Tropical Storm (WSW Bahia Tortugas, Mexico)

NWS National Hurricane Center Miami FL 1000 AM CDT Mon Aug 17, 2020 

Data from a recent SSMIS microwave overpass reveals that an eye is trying to form underneath the deep convection of Genevieve, but there is some dry air near the center that may be disrupting the formation of a solid eyewall. Despite that dry air, large bands continue to the southwest and northwest of the center, and the deep convection over the center is expanding in size. The latest Dvorak satellite intensity estimates from both TAFB and SAB support raising the initial intensity to 65 kt, making Genevieve the third hurricane of the 2020 Eastern Pacific hurricane season.

Genevieve jogged a little northwest over the past few hours, but the longer term motion has been west-northwest at 16 kt. The main steering mechanism for the cyclone is a strong mid-level ridge which extends from the southwestern United States southeastward into Mexico. The model guidance varies slightly on the strength and orientation of this ridge over the next few days, which could play a role in how close Genevieve gets to the southern portion of the Baja California Peninsula. The GFS is the farthest east, but still keeps the center well offshore, while The UKMET is the westernmost solution. Overall, the guidance has changed little since early this morning, and the official forecast is very near the previous track, which lies near the TVCX/TVCE consensus.

The small amount of dry air near the center should get worked out of the circulation shortly, and there is high confidence that the rapid intensification of Genevieve will continue for the next 24-36 h. The SHIPS Rapid Intensification Index (RII) shows a greater than 95 percent chance of a 30 kt increase in strength in the next 24 h, and nearly an 80 percent chance of a 45 kt increase in the next 36 h. The global, regional, and consensus intensity aids all agree that rapid intensification will occur in one form or another during this time frame as well. The official intensity forecast is a blend of the HFIP corrected consensus and the IVCN consensus, and is very close to the previous forecast.

Large swells generated by Genevieve are expected to begin affecting portions of the coast of southern Mexico today and will spread northward along the coast of Mexico to the Baja California peninsula by Wednesday.

FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 14.3N 103.0W   65 KT  75 MPH - Category 1 (WSW Acapulco, Mexico)
 12H  18/0000Z 15.4N 105.0W   85 KT 100 MPH - Category 2 (WSW Acapulco, Mexico)
 24H  18/1200Z 17.0N 107.3W  105 KT 120 MPH - Category 3 (WSW Lázaro Cárdenas, Mexico)
 36H  19/0000Z 18.4N 109.0W  120 KT 140 MPH - Category 4 (ESE Isla Sorroco, Mexico)
 48H  19/1200Z 19.7N 110.2W  120 KT 140 MPH - Category 4 (ENE Isla Sorroco, Mexico)
 60H  20/0000Z 21.0N 111.1W  110 KT 125 MPH - Category 3 (WSW Cabo San Lucas, Mexico)
 72H  20/1200Z 22.2N 112.4W   95 KT 110 MPH - Category 2 (WSW Cabo San Lucas, Mexico)
 96H  21/1200Z 24.3N 115.2W   65 KT  75 MPH - Category 1 (WSW Cabo San Lucas, Mexico)
120H  22/1200Z 26.4N 118.7W   45 KT  50 MPH - Tropical Storm (WSW Punta Abreojos, Mexico)

NWS National Hurricane Center Miami FL 1000 PM CDT Sun Aug 16, 2020

Infrared (IR) and passive microwave (MW) satellite imagery indicate that Genevieve has continued to rapidly intensify while becoming better organized. A 17/0121Z SSMI/S MW image showed that the cyclone had already developed a 15-nmi-diameter, ragged mid-level eye, while both IR and MW data indicate tight banding features spiraling into a compact inner-core convective region. The initial intensity of 50 kt is based on unanimous T3.0/45 kt satellite classifications from TAFB and SAB, with the aforementioned eye feature nudging upward the final intensity assessment. The initial motion estimate remains west-northwestward or 290/16 kt. The track forecast and reasoning remain unchanged and fairly straightforward. Genevieve is expected to move generally west-northwestward around the southwestern periphery of a sprawling deep-layer ridge located over the western United States and northern and central Mexico throughout the forecast period. The new NHC track forecast is very similar to the previous advisory track, and lies near the middle of the tightly packed consensus track model forecasts.

Now that Genevieve has developed a tight inner-core wind field and an eye feature, it isn’t a question of will the cyclone rapidly strengthen, but rather how quickly and how much will the strengthening be! The deep-layer and mid-level vertical wind shear parameters are forecast to be weak at less than 5 kt through 72 hours, while the upper-level outflow pattern is expected to steadily improve during that time, including the development of dual outflow channels to the north and south.

These very favorable atmospheric conditions will coincide with a very moist mid-level regime and sea-surface temperatures (SST) of at least 30 deg C. As a result, the intensity forecast has been nudged upward, with rapid intensification (RI) of about 30 kt expected during next 24 h, followed by a slightly faster rate of RI in the 24-48 hour time frame when the dual outflow channels will be present. By 60-72 hours, Genevieve is expected to be moving over shallower warm water, which should result in significant cold upwelling and the onset weakening. More rapid weakening is forecast thereafter due to the cyclone moving over 23-25 deg C SSTs. The official intensity is near the upper end of the guidance envelope, but remains below the ECMWF-based SHIPS model forecast which brings Genevieve to near 130 kt in 48-60 hours.

Although the tropical cyclone is forecast to remain well offshore of the southern coast of Mexico, large swells generated by the strengthening system are expected to begin affecting portions of the coast of southern Mexico over the next day or so.

FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 12.4N 100.4W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, Mexico)
 12H  17/1200Z 13.4N 102.7W   60 KT  70 MPH - Tropical Storm (WSW Acapulco, Mexico)
 24H  18/0000Z 14.8N 105.7W   75 KT  85 MPH - Category 1 (SW Acapulco, Mexico)
 36H  18/1200Z 16.3N 108.2W   95 KT 110 MPH - Category 2 (SW Acapulco, Mexico)
 48H  19/0000Z 17.7N 110.1W  115 KT 130 MPH - Category 4 (WSW Manzaniilo, Mexico)
 60H  19/1200Z 19.1N 111.5W  120 KT 140 MPH - Category 4 (ESE Isla Sorroco, Mexico)
 72H  20/0000Z 20.4N 112.9W  105 KT 120 MPH - Category 3 (WSW Cabo San Lucas, Mexico)
 96H  21/0000Z 22.7N 116.0W   80 KT  90 MPH - Category 1 (WSW Cabo San Lucas, Mexico)
120H  22/0000Z 24.7N 119.7W   55 KT  65 MPH - Tropical Storm (WSW San Juanico, Mexico)

NWS National Hurricane Center Miami FL 400 PM CDT Sun Aug 16, 2020 

Visible satellite imagery shows that the tropical cyclone is quickly becoming better organized. Several bands of deep convection are located around the center, and there is a concentration of convection near the estimated center, suggesting that a CDO may already be starting to form. The various satellite intensity estimates were around 35 kt at 18z, and an earlier ASCAT overpass revealed a couple of wind vectors slightly higher than that value. Based on the continued increase in organization, the advisory intensity has been set at 40 kt. Genevieve becomes the seventh named storm in the eastern Pacific basin this hurricane season.

Although there are a few dry slots noted within the bands of deep convection, environmental conditions of warm water, low shear, and plenty of low- to mid-level moisture along the forecast track suggest that Genevieve will intensify quite rapidly over the next couple of days. The statistical and dynamical guidance, along with the global models, deepen the cyclone rapidly over the next 2-3 days. The latest SHIPS Rapid Intensification Index shows about a 65-percent chance of 65-kt increase in wind speed over the next 72 hours, and DTOPS gives a 90-percent chance of a similar increase in intensity over that same time period. All of this leads to an unusually high level of confidence that Genevieve will rapidly strengthen, likely becoming a hurricane in 24 hours and a major hurricane within 48 hours. The NHC intensity forecast is similar to both the SHIPS and HFIP corrected consensus models. After 72 h, Genevieve is expected to reach cooler waters, and a fairly quick rate of weakening is forecast after that time.

Recent satellite fixes suggest that the center is located slightly north of the previous track, but Genevieve’s motion remains west-northwestward at a brisk 17 kt. The track forecast philosophy is unchanged from before. Genevieve should move west-northwestward to the south of a deep layer ridge over the western United States during the next couple of days. After that time, the cyclone will be approaching the western portion of the ridge and a slightly slower northwestward motion is expected. The new NHC track forecast is slightly north of the previous advisory through 24 hours due to the more northward initial position, otherwise the updated forecast is similar to the previous advisory, and is close to the HFIP corrected consensus model. Although the tropical cyclone is forecast to remain well offshore the southern coast of Mexico, large swells generated by the strengthening system are expected to begin affecting portions of the coast of southern Mexico over the next day or so.

FORECAST POSITIONS AND MAX WINDS

INIT  16/2100Z 12.2N  99.2W   40 KT  45 MPH - Tropical Storm (WSW Acapulco, Mexico)
 12H  17/0600Z 12.9N 101.5W   50 KT  60 MPH - Tropical Storm (WSW Acapulco, Mexico)
 24H  17/1800Z 14.3N 104.5W   65 KT  75 MPH - Category 1 (WSW Acapulco, Mexico)
 36H  18/0600Z 15.7N 107.2W   85 KT 100 MPH - Category 2 (WSW Acapulco, Mexico)
 48H  18/1800Z 17.2N 109.3W  100 KT 115 MPH - Category 3 (WSW Manzaniilo, Mexico)
 60H  19/0600Z 18.6N 110.9W  110 KT 125 MPH - Category 3 (ESE Isla Sorroco, Mexico)
 72H  19/1800Z 20.2N 112.4W  105 KT 120 MPH - Category 3 (WSW Cabo San Lucas, Mexico)
 96H  20/1800Z 22.5N 115.3W   80 KT  90 MPH - Category 1 (WSW Cabo San Lucas, Mexico)
120H  21/1800Z 24.7N 119.1W   55 KT  65 MPH - Tropical Storm (WSW San Juanico, Mexico)

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

At the moment the depression is nearly devoid of convection, except for a very small weakening burst over 100 n mi from the center. In fact, there has not been any deep convection within 50 n mi of the center since yesterday, and this convection has been sporadic. The available Dvorak T-numbers only support 25 kt. However, given that an earlier ASCAT overpass had a few vectors with higher values, the initial intensity remains 30 kt. The depression is barely fitting the definition of a tropical cyclone due to the lack of persistent organized deep convection. If the system is not able to generate sustained organized convection, it could become a post-tropical remnant low at any time.

Simulated satellite imagery from the global models suggest this lack of persistent convection may continue, and therefore the official forecast no longer keeps the system a tropical cyclone through 5 days. The official intensity forecast is generally in line with the intensity consensus aids throughout the 5 day time period, but makes the cyclone

NWS National Hurricane Center Miami FL 1100 AM PDT Sat Aug 15, 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Tropical Depression Ten-E, located more than 1500 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. A trough of low pressure located a few hundred miles west of the southern tip of the Baja California Peninsula is producing a small area of showers. This system has moved over colder waters and further development is unlikely. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…near 0 percent.
  • 2. A large area of persistent showers and thunderstorms associated with an area of low pressure is located several hundred miles southwest of the southern tip of the Baja California peninsula. The disturbance does not appear to have developed a well-defined center yet, but conditions are expected to be favorable for further development today and tomorrow, and tropical depression is likely to form during that time. This system is forecast to move slowly north-northwestward or northward during the next couple of days. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…80 percent.
  • 3. A low pressure system located several hundred miles southeast of the Gulf of Tehuantepec continues to show signs of development. A broad and elongated closed low pressure system has formed, and the associated shower and thunderstorm activity is beginning to organize into bands. Although recent satellite-derived wind data indicate that the system does not yet have a well-defined center, environment conditions appear conducive for further development. A tropical depression or tropical storm will likely form tonight or on Sunday while the system moves generally west-northwestward just offshore of the southwestern coast of Mexico. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Sat Aug 15, 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Tropical Depression Ten-E, located more than 1500 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. An area of low pressure located a few hundred miles west of the southern tip of the Baja California Peninsula is producing a small area of showers. This system has moved over colder waters and further development is unlikely. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…20 percent.
  • 2. Concentrated shower and thunderstorm activity associated with an area of low pressure is located several hundred miles southwest of the southern tip of the Baja California peninsula. This system has slowly become better organized since yesterday and environmental conditions appear favorable for further development today and tomorrow. A tropical depression is likely to form while the system moves slowly north-northwestward or northward during the next couple of days. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…80 percent.
  • 3. Showers and thunderstorms associated with a trough of low pressure located several hundred miles southeast of the Gulf of Tehuantepec are beginning to show signs of organization. Conditions appear conducive for further development and a tropical depression or tropical storm is likely to form later this weekend or early next week while the system moves generally west-northwestward just offshore of the southwestern coast of Mexico. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 1100 PM PDT Fri Aug 14, 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Tropical Depression Ten-E, located more than 1500 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. An area of low pressure located about 150 miles southwest of the southern tip of the Baja California peninsula has become a little better defined since yesterday. However, the associated shower activity remains limited. While some additional development of this system is possible, the low is forecast to move over cooler waters on Saturday and the chance of this system becoming a tropical depression appears to be decreasing. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…40 percent.
  • 2. Another area of disturbed weather associated with a broad area of low pressure is located about 700 miles southwest of the southern tip of the Baja California peninsula. Environmental conditions are expected to be conducive for the development of this system, and it is likely to become a tropical depression while it moves slowly north-northwestward or northward during the next few days. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high...70 percent.
  • 3. A trough of low pressure continues to produce disorganized showers and thunderstorms just offshore of the Pacific coast of Central America. Conditions are expected to be conducive for a low pressure system to develop from this trough over the next day or so, and a tropical depression or storm is likely to form this weekend or early next week while the system moves generally west-northwestward just offshore of the southwestern coast of Mexico. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Fri Aug 14 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Tropical Depression Ten-E, located more than 1500 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. Satellite data indicate that the circulation associated with an area of low pressure located about 175 miles south-southwest of the southern tip of the Baja California peninsula has become a little better defined since yesterday. However, the associated shower activity remains limited. While some additional development of this system is possible, the low is forecast to reach cooler waters on Saturday and the chance of this system becoming a tropical depression appears to be decreasing. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…medium…60 percent.
  • 2. Another area of disturbed weather associated with a trough of low pressure is located about 800 miles southwest of the southern tip of the Baja California peninsula. Environmental conditions are expected to be favorable for the development of this system and it is likely to become a tropical depression while it moves slowly north-northwestward or northward during the next few days. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…70 percent.
  • 3. A trough of low pressure continues to produce disorganized showers and thunderstorms just offshore of the Pacific coast of Central America. Conditions are expected to be conducive for a low pressure system to develop from this trough over the next day or so, and a tropical depression or storm is likely to form this weekend or early next week while the system moves generally west-northwestward just offshore of the southwestern coast of Mexico. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Fri Aug 14, 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Tropical Depression Ten-E, located about 1500 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. An elongated area of low pressure stretches from a few hundred miles south of the southern tip of the Baja California peninsula southwestward several hundred miles. The northeastern portion of the trough has slowly organized during the past couple of days and is producing persistent shower and thunderstorm activity. Environmental conditions are expected to be conducive for development and a tropical depression is likely to form during the next day or so while the system moves west-northwestward or northwestward at 10 to 15 mph. The system is forecast to move over colder waters over the weekend and further development is unlikely after that time. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…80 percent.
  • 2. The southwestern portion of the aforementioned trough is also producing a large are of disturbed weather nearly 1000 miles southwest of the southern tip of the Baja California peninsula. Environmental conditions are expected to be favorable for the development of this system and it could become a tropical depression while it moves slowly northward during the next few days. after that time. * Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…medium…60 percent.
  • 3. A trough of low pressure is producing disorganized showers and thunderstorms just offshore of the Pacific coast of Central America. Conditions are expected to be conducive for a low pressure system to develop from this trough over the next couple of days, and a tropical depression is likely to form this weekend or early next week while the system moves generally west-northwestward just offshore of the southwestern coast of Mexico. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high…80 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Thu Aug 13 202

For the eastern North Pacific…east of 140 degrees west longitude:
The National Hurricane Center is issuing advisories on Tropical Depression Ten-E, located about 1500 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. A large area of disorganized showers and thunderstorms continues in association with a surface trough of low pressure located a few hundred miles west-southwest of Manzanillo, Mexico. Even though this system has been slow to organize, environmental conditions are expected to be conducive for development, and a tropical depression is likely to form within the next day or two before the system reaches cooler waters later this weekend. This system is forecast to move west-northwestward at 10 to 15 mph away from the west-central coast of Mexico. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…90 percent.
  • 2. A trough of low pressure is located just offshore the Pacific coast of Central America. Conditions are expected to be conducive for a low to develop from this trough over the next couple of days, and and a tropical depression is likely to form this weekend or early next week while the system moves generally west-northwestward just offshore of the southwestern coast of Mexico. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…high…80 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Thu Aug 13, 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center has initiated advisories on Tropical Depression Ten-E, located about 1400 miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. A large area of disorganized showers and thunderstorms, associated with a trough of low pressure, extends several hundred miles southwest of the southwestern coast of Mexico. Environmental conditions appear conducive for development, and a tropical depression is expected to form within the next few days before the system reaches cooler waters later this weekend. This system is forecast to move west-northwestward at 10 to 15 mph away from the coast of southwestern Mexico. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.
  • 2. A trough of low pressure has developed just offshore the Pacific coast of Central America. Conditions are expected to be conducive for a low to develop from this trough over the next few days, and and a tropical depression is likely to form this weekend or early next week while the system moves generally west-northwestward offshore of the coast of Mexico. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…high…70 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Wed Aug 12 2020 

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on recently downgraded Tropical Storm Elida, located several hundred miles southwest of Punta Eugenia, Mexico.

  • 1. Satellite images suggest that a better-defined low-pressure area is forming about 1300 miles southwest of the southern tip of the Baja California peninsula, and the associated shower and thunderstorm activity is becoming a little better organized. Environmental conditions are conducive for additional development, and a tropical depression is expected to form within the next couple of days while the system moves slowly west-northwestward. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high…90 percent.
  • 2. A large area of disturbed weather associated with a trough of low pressure extends several hundred miles southwest of the southwestern coast of Mexico. Environmental conditions appear conducive for development, and a tropical depression is expected to form during the next few days before the system reaches cooler waters over the weekend. This system is forecast to move west-northwestward at about 15 mph away from the coast of southwestern Mexico. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.
  • 3. Another area of low pressure is expected to form in a few days over the far eastern portion of the basin to the south of the coast of Central America. Conditions are expected to be conducive for development, and a tropical depression is likely to form this weekend or early next week while it moves generally west-northwestward just offshore the coast of Mexico. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…high…70 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Wed Aug 12,  2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Hurricane Elida, located about 500 miles west of the southern tip of the Baja California peninsula.

  • 1. An elongated area of low pressure located about 1300 miles southwest of the southern tip of the Baja California continues to produce a broad area of cloudiness and disorganized showers and thunderstorms. Environmental conditions are conducive for development, and a tropical depression is likely to form within the next couple of days while the system moves slowly west-northwestward. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.
  • 2. A large area of disturbed weather associated with a trough of low pressure extends from just west of the Gulf of Tehuantepec southwestward for several hundred miles. Environmental conditions appear conducive for development, and a tropical depression is likely to form during the next few days before the system reaches cooler waters over the weekend. This system is forecast to move west-northwestward at about 15 mph away from the coast of southwestern Mexico. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…high…90 percent.
  • 3. Another area of low pressure is expected to form in a few days over the far eastern portion of the basin to the south of the coast of Central America. Conditions are expected to be conducive for development, and a tropical depression could form this weekend or early next week while it moves generally west-northwestward just offshore the coast of Mexico. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…60 percent.
  • 4. Another area of disturbed weather is forecast to form near or west of the border between the National Hurricane Center and Central Pacific Hurricane Center areas of responsibility. Some subsequent gradual development of this system is possible later this week while the system moves slowly westward in the central Pacific basin. Future information on this system will be included in Tropical Weather Outlooks issued by the Central Pacific Hurricane Center. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Tue Aug 11, 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Hurricane Elida, located a few hundred miles west of the southern tip of the Baja California peninsula.

  • 1. Recent satellite wind data indicate that the area of low pressure located about 1300 miles southwest of the southern tip of the Baja California peninsula remains elongated. The associated shower and thunderstorm activity is currently disorganized, but environmental conditions are expected to be conducive for additional development, and a tropical depression is likely to form within the next few days. The system is not expected to move as quickly westward as originally forecast, and a slower westward to west-northwestward motion is now anticipated over the next several days. * Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…high...80 percent.
  • 2. A large area of disturbed weather associated with a trough of low pressure extends from just west of the Gulf of Tehuantepec southwestward for several hundred miles. Environmental conditions appear conducive for gradual development over the next several days, and this system will likely become a tropical depression by late this week while it moves generally west-northwestward away from the coast of southwest Mexico. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high…80 percent.
  • 3. Another area of low pressure is expected to form in a few days over the far eastern portion of the basin to the south of the coast of Central America. Conditions are expected to be conducive for development, and a tropical depression could form this weekend while it moves generally west-northwestward. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…60 percent.
  • 4. Another area of disturbed weather is forecast to form over the far western portion of the eastern Pacific basin within the next couple of days. Some subsequent gradual development of this system is possible later this week while the system moves slowly westward into the central Pacific basin. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 1100 AM PDT Tue Aug 11, 2020

For the eastern North Pacific…east of 140 degrees west longitude: The National Hurricane Center is issuing advisories on Hurricane Elida, located a few hundred miles west-southwest of the southern tip of the Baja California peninsula.

  • 1. Satellite imagery indicates that a poorly defined low pressure area has formed in association with the elongated area of disturbed weather located around 1300 miles southwest of the southern tip of the Baja California peninsula. Additional development is expected, and a tropical depression is likely to form during the next few days. The system is expected to move slowly westward toward the central Pacific basin during the next several days. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high…70 percent.
  • 2. An area of disturbed weather is located a few hundred miles south- southwest of the Gulf of Tehuantepec. An area of low pressure is forecast to develop from this system well south or southwest of the southwestern coast of Mexico in a couple of days. Environmental conditions appear conducive for development thereafter, and this system will likely become a tropical depression late this week or over the weekend while it moves generally west-northwestward. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…high…80 percent.
  • 3. Another area of low pressure is expected to form in a few days over the far eastern portion of the basin to the south of the coast of Central America. Gradual development of this system is possible, and a tropical depression could form this weekend while it moves generally west-northwestward. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 500 AM PDT Tue Aug 11, 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Hurricane Elida, located a few hundred miles southwest of the southern tip of the Baja California peninsula.

  • 1. An elongated area of disturbed weather is located around 1500 miles southwest of the southern tip of the Baja California peninsula. A low-pressure system is expected to form within this area in a day or two, and it will likely become a tropical depression late this week. The system is expected to move slowly westward toward the central Pacific basin during the next several days. * Formation chance through 48 hours…low…30 percent. * Formation chance through 5 days…high…70 percent.
  • 2. An area of disturbed weather has formed a few hundred miles south of the Gulf of Tehuantepec. An area of low pressure is forecast to develop from this system well south or southwest of the southwestern coast of Mexico in a couple of days. Environmental conditions appear conducive for development thereafter, and this system will likely become a tropical depression late this week or over the weekend while it moves generally west-northwestward. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…high…70 percent.
  • 3. Another area of low pressure is expected to form in a few days over the far eastern portion of the basin to the south of the coast of Central America. Gradual development of this system is possible, and a tropical depression could form this weekend while it moves generally west-northwestward. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 500 PM PDT Mon Aug 10, 2020

For the eastern North Pacific…east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on recently upgraded Hurricane Elida, located less than 100 miles north- northwest of Socorro Island.

  • 1. Disorganized showers and thunderstorms associated with a trough of low pressure are centered about 1500 miles southwest of the southern tip of the Baja California peninsula. An area of low pressure is expected to form from this system in a day or two, and it will likely become a tropical depression late this week. The system is expected to move slowly westward toward the central Pacific basin during the next several days. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…high…70 percent.
  • 2. An area of low pressure is forecast to develop well offshore of the southwestern coast of Mexico in a couple of days. Environmental conditions appear conducive for development thereafter, and this system will likely become a tropical depression by late this week while it moves generally west-northwestward. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…high…70 percent.
  • 3. Another area of low pressure is expected to form in a few days over the far eastern portion of the basin to the south of the coast of Central America. Gradual development of this system is possible, and a tropical depression could form this weekend while it moves generally west-northwestward. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium...40 percent.

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

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Video: MEXICO Hurricane Genevieve | leaving severe flooding in Los Cabos, Baja California Sur, August 19