*******Note that forecast and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********
...MONDAY AUGUST 21 2023 1:15 PM EDT...
The Atlantic tropics remain quiet active with now three named systems lining the tropical latitudes of the Atlantic from the eastern Caribbean to the open central Atlantic... see Emily... Franklin... and Gert sections below for more details. Note Franklin has potential to bring notable impacts to Haiti... the Dominican Republic... and Puerto Rico tomorrow through Wednesday. In addition... a tropical wave of low pressure now in the Gulf of Mexico is becoming better organized and has a high chance of moving into the Texas/Mexico border region as a strengthenign tropical storm over the next 36 hours... see area of interest #22 section below for more information. Area of interest #23... a tropical wave of low pressure continuing to move across the eastern tropical Atlantic... will have a special update done for it later today on this site.
Note that the forecasts and outlooks below were completed at 0600Z earlier today. Any changes that have occurred with each area of interest or active tropical cyclone since then are noted on each respective section below.
TROPICAL STORM GERT... As of midnight EDT earlier today the NHC upgraded Tropical Depression Six... located east of the northern Lesser Antilles islands... to Tropical Storm Gert. This was based on a satellite scan of winds finding 40 mph maximum sustained winds underneath a thunderstorm burst in the circulation's eastern semircircle. The thunderstorm activity has been lopsided to the east half of Gert due to ongoing westerly shear. For the forecast track Gert is expected to continue west but with some northward angle due to a western Atlantic surface ridge weakness that will be kicked off by the arrival of an eastern Canada surface cold front and its amplified upper trough into the western Atlantic. I have extended the amount of time for Gert being a tropical cyclone as the shear may abate a little in the short-term as the current shearing western Atlantic upper vorticity will be lifted northward while pulled toward the aforementioned front's upper trough. For the longer-term... beyond 12 hours... the shear is likely to increase again as Gert approaches the strong upper outflow of Tropical Storm Franklin and so I forecast Gert to weaken back to a depression by 24 hours and be dissipating by 48 hours. Impacts to the northern Lesser Antilles are expected to be neglible... with maybe some rainfall at most by later Tuesday... that is if the dissipating circulation of Gert is still around by that time.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0600Z Aug 21)... 40 mph maximum sustained wind tropical storm centered at 16.7N-55.9W
IOH 24 Hr Forecast (0600Z Aug 22)... 35 mph maximum sustained wind tropical depression centered just east of the northern Lesser Antilles at 17.5N-60W
IOH 48 Hr Forecast (0600Z Aug 23)... Remnant trough located just north-northwest of the northern Lesser Antilles near 18.5N-63W
****** National Hurricane Center (hurricanes.gov) official forecast as of 11 AM EDT****************************
Loss of tropical cyclone status (0000Z Aug 22)... 35 mph maximum sustained wind remnant low centered east of the northern Lesser Antilles at 17.2N-58W
TROPICAL STORM EMILY (RECENTLY DOWNGRADED TO REMNANTS OF EMILY)... Shower and thunderstorm activity associated with large Tropical Storm Emily has been torn away and dissipated over the last 24 hours due to Emily moving closer to a shearing string of upper vortiicty. As a result Emily is now a large cloud swirl likely to be downgraded to a remnant low soon. The shallow remnant low is now decopuled from the westerly upper winds that have been dampening Emily's westward progress... and the models have now trended with a faster westward speed for the short-term which is what is shown in my updated forecast track below. Emily is expected to continue west-northwest around the southwest edge of the Atlantic surface ridge... and then turn northward around 50W longitude into a western Atlantic surface ridge weakness that will be kicked off by the arrival of an eastern Canada surface cold front and its amplified upper trough into the western Atlantic. Duringits northward turn the current western Atlantic upper vorticity will be kicked toward Emily as an amplified upper trough whose eastern divergence zone potentially aids Emily. Its possible that Emily simply degenerates into an elongated north-south trough that becomes absored by the incoming western Atlantic cold front... as the upper trough will have an elongated upper divergence zone. Or alternatively Emily could re-generate into a tropical cyclone with the initial help from the upper trough... followed by arrival into more favorable warm core upper ridging with low shear and upper outflow associated with the warm surface southerly flow ahead of the incoming frontal system. My forecast continues to call for Emily making a comeback during its northward turn... but with only a conservative slow strengthening rate as it is unclear if or how much Emily will fall apart under the current short-term shear followed by elongation during its interaction with the aforementioned elongated upper trough.
Update as of 11 AM EDT... Emily has indeed been downgraded by the NHC to a remnant low pressure.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0600Z Aug 21)... 45 mph maximum sustained wind tropical storm centered in the eastern tropical Atlantic at 20.5N-40.2W
IOH 24 Hr Forecast (0600Z Aug 22)... Remnant low centered in the central Atlantic at 21.7N-45W
IOH 48 Hr Forecast (0600Z Aug 23)... Remnant low centered in the central Atlantic at 22.7N-50W
IOH 72 Hr Forecast (0600Z Aug 24)... Remnant low centered in the central Atlantic at 26N-50W
IOH 96 Hr Forecast (0600Z Aug 25)... 40 mph maximum sustained wind tropical storm centered in the central Atlantic at 31.5N-50W
IOH 120 Hr Forecast (0600Z Aug 26)... 50 mph maximum sustained wind tropical storm centered in the central Atlantic at 39N-50W
******National Hurricane Center (hurricanes.gov) official forecast as of 11 AM EDT*****************************
Dissipation of Remnants (1200Z Aug 24)... Dissipating remnant low centered in the central Atlantic at 29.5N-49.7W
TROPICAL STORM FRANKLIN... Per special update #58A late yesterday... the eastern Caribbean tropical wave of low pressure has intensified into Tropical Storm Franklin with 50 mph maximum sustained winds. This system is north of my previous forecast track from full update #58 and so my updated track is adjusted accordingly. Essentially thru day 5 the forecast track is a reversal of the current west-northwest trajectory to an east-northeastward one as Franklin gets pulled toward a sprawling surface ridge weakness consisting of a surface front that moves into the western Atlantic from its current eastern Canada position... combined with Emily. Regarding intensity... Franklin is in a battle with westerly shear being generated out ahead of lingering northwestern Caribbean upper vorticity. However Franklin is defiant in its battle while producing an impressively large and strong storm mass covering the center and eastern half of this system and so I forecast some additional strengthening before Franklin makes landfall with the south coast of Haiti or the Dominican Republic (Hispaniola). Some weakening is shown between 24 and 48 hours which is a reflection of the landfall with Hispaniola... in addition to steady wind shear as upper vorticity from the southeastern US gets pushed toward Franklin by the central US upper ridge. The shear may relax by 72 hours as the upper vorticity begins to retrograde away while continuing to be pushed around the central US upper ridge... however only gradual strenghtening is shown as it is unclear how disrupted Franklin's circulation will be from its interaction with the mountanious terrain of Hispaniola while also being sheared. I do not show any strengthening between 72 and 96 hours as the shear likely increases again as the southern base of the upper trough associated with the western Atlantic surface front nears Franklin. My 5-day intensity forecast then ends with Franklin finally able to become a hurricane as the shearing upper trough lifts northeastward and away due to the strength of the warm air mass upper ridge ahead of the surface front.
Regarding impact to land areas:
(1) The tropical storm is headed for a tomorrow through Wednesday passage across Haiti and the Dominican Republic where preparations for heavy rainfall with flash flood and mudslide potential... gusty winds... and coastal surf should now be underway. Due to the current forecast track and due to westerly shear regime... the worst of the heavy rain and gusty winds will be further east toward the Dominican Republic. Also noting the tropical storm continues producing quiet strong thunderstorms covering the center despite the shear... should this activity produce enough latent heat release and a shear-reducing warm core upper anticyclone it could strengthen more quickly in the short-term than shown below and possibly become a category 1 hurricane before the center makes landfall on the south coast of Haiti or the Dominican Republic... I recommend for the south coast to prepare for the winds and coastal surf of a category 1 just in case.
(2) For the eastern Bahamas... the current forecast track combined with the westerly shear regime likely means heavy rainfall and gusty winds will stay east of the islands. However coastal surf is likely for the islands by Wednesday.
(3) For Puerto Rico... the westerly shear pattern means Franklin’s eastern squalls will be pushed toward the island by tomorrow thru Wednesday. Rainfall flooding cannot be ruled out here.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0600Z Aug 21)... 50 mph maximum sustained wind tropical storm centered in the eastern Caribbean at 15N-68.8W
IOH 24 Hr Forecast (0600Z Aug 22)... 60 mph maximum sustained wind tropical storm centered just south of the Haiti/Dominican Republic border at 16.2N-71.5W
IOH 48 Hr Forecast (0600Z Aug 23)... 50 mph maximum sustained wind tropical storm centered just north of the Dominican Republic and just south-souheast of the eastern Bahamas at 20.5N-71W
IOH 72 Hr Forecast (0600Z Aug 24)... 60 mph maximum sustained wind tropical storm centered in the western Atlantic at 24N-66W
IOH 96 Hr Forecast (0600Z Aug 25)... 60 mph maximum sustained wind tropical storm centered in the western Atlantic at 25.5N-62W
IOH 120 Hr Forecast (0600Z Aug 26)... 75 mph maximum sustained wind hurricane centered in the central Atlantic at 26N-58.5W
******National Hurricane Center (hurricanes.gov) official forecast as of 11 AM EDT*****************************
Landfall (0000Z Aug 23)... 65 mph maximum sustained wind tropical storm centered at 17.3N-70.9W
5-day Position (1200Z Aug 26)... 85 mph maximum sustained wind hurricane centered in the western Atlantic at 26.4N-63.7W
AREA OF INTEREST #22 (POTENTIAL TROPICAL CYCLONE NINE)... The northern apex of the tropical wave of low pressure that had been crossing the western Caribbean has fractured off into a seperate central Gulf of Mexico surface trough of low pressure. The surface trough has been exhibiting a pattern of organized northern squalls of thunderstorms whose upper outflow is fanning around the west side of an eastern Gulf of Mexico upper ridge cell. The southern side of the surface trough has been void of of thundestorms due to light southerly shear induced by the east side of upper vorticity currently over southern Texas and northern Mexico. The shear is expected to remain light as the upper vorticity continues to retrograde westward and away around the current central US upper ridge... therefore tropical cyclone formation is likely. As a result the NHC has upgraded this area of interest to potential tropical cyclone nine in order to begin issuing tropical storm advisories for the southern Texas coast. I have also begun a track and intensity forecast as outlined below in anticipation of tropical cyclone formation due to this system's ongoing increase in organization. Calling for this system to gradually strengthen till its landfall just north of the Texas/Mexico border. The west-northwest steering into the Texas/Mexico border region will be provided by an eastern North America surface ridge that will be building under the western convergence zone of the current eastern Canada upper trough now heading toward the western Atlantic. Gusty winds with some damage potential... generated under thunderstorm activity... will likely remain north of the center due to the light southerly shear... reaching the far southern Texas coast by tomorrow. This will also be the location of coastal surf as the flow on the north side of the circulation will be easterly and onshore. Heavy rainfall with flash flood potential will also be overspreading northern Tamaulipas and southern Texas by tomorrow. Preparations for the above impacts should now be underway and be completed by tomorrow morning.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0600Z Aug 21)... 30 mph maximum sustained wind surface trough located in the central Gulf of Mexico near 24N-90W
IOH 24 Hr Forecast (0600Z Aug 22)... 50 mph maximum sustained wind tropical storm centered in the western Gulf of Mexico at 25N-95W
IOH 36 Hr Forecast (1800Z Aug 22)... 60 mph maximum sustained wind tropical storm centered just offshore of the Texas/Mexico border at 26N-97W
IOH 48 Hr Forecast (0600Z Aug 23)... 30 mph maximum sustained wind tropical depression centered over far southern Texas at 26.5N-99W
IOH 72 Hr Forecast (0600Z Aug 24)... Dissipation over the central part of the Texas/Mexico border near 29.5N-100.5W
******National Hurricane Center (hurricanes.gov) official outlook as of 8 AM EDT****************************
Formation chance through 48 hours...90%
Formation chance through 7 days (168 hours)...90%
******National Hurricane Center (hurricanes.gov) official forecast as of 11 AM EDT*****************************
Peak Strength (1200Z Aug 22)... 45 mph maximum sustained wind tropical storm centered just offshore of southern Texas at 26.6N-96.8W
Loss of Tropical Cyclone Status (0000Z Aug 23)... 30 mph maximum sustained wind remnant low centered over the central Texas/Mexico border at 27.8N-100.1W
AREA OF INTEREST #23... The tropical wave of low pressure that has recently entered the eastern tropical Atlantic from western Africa features a broad surface low pressure spin whose central area recently passed over the Republic of Cabo Verde Islands. Due to the number of other active disturbances and storms... have not been able to issue an updated outlook (with track forecast and probabilites of tropical cyclone formation) in this update. Will do so in a special update later today.
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
1200Z (Aug 20) CMC Model Run...
**For Tropical Storm Gert... weakens to a remnant low that passes just northeast of the northern Lesser Antilles at 60 hours... remnant low reverses to a southeastward drift while pulled by a surface ridge weakness caused by Emily and AOI #23 and reaches 16.2N-59W at 120 hours
**For Tropical Storm Emily... continues west-northwest to 24N-52.5W through 84 hours while weakening to a broad remnant low... remnant low curves northward and regains tropical cyclone status through 120 hours while reaching 30N-54W
**For Tropical Storm Franklin... reaches 14.8N-74.8W through 48 hours after which time it turns northward and passes between Haiti and Cuba through 90 hours... through 114 hours makes a sharp turn eastward across the southeastern Bahamas and begins to briskly strnegthen while lifting northeastward away from the Bahamas by 120 hours.
**For area of interest #22... no development shown
**For area of interest #23... passes over the Republic of Cabo Verde Islands through 18 hours as a broad tropical low... strengthens into a tropical cyclone near 18.8N-36.5W through 84 hours... tropical cyclone reaches 20N-41.5W at 120 hours.
**Tropical wave emerges from the west coast of Africa at 72 hours followed by a second wave at 132 hours... both waves merge into a tropical low near 11N-24W at 144 hours... tropical low strengthens into a tropical cyclone near 12N-32.5W through 168 hours
1200Z (Aug 20) ECMWF Model Run...
**For Tropical Storm Gert... dissipates just east of the northern Lesser Antilles and near 17.5N-60W at 42 hours
**For Tropical Storm Emily... achieves peak strength near 20.2N-40W at 12 hours after which time it continues west-northwest and weakens to a remnant low near 23.5N-45.5W at 54 hours... remnant low turns north where it weakens further to a trough near 31N-50W at 96 hours
**For Tropical Storm Franklin... degenerates into an elongated surface trough spanning from Jamaica to the waters between Haiti and the eastern Bahamas through 78 hours... east end of the trough develops into a tropical cyclone east-northeast of the eastern Bahamas through 120 hours.
**For area of interest #22... no development shown
**For area of interest #23... passes over the Republic of Cabo Verde Islands as a broad tropical low at 18 hours... develops into a tropical cyclone near 21.5N-41W at 120 hours.
**Tropical wave emerges from western Africa at 72 hours and organizes into a tropical low that passes south of the Republic of Cabo Verde Islands thorugh 108 hours... tropical low reaches 14.5N-26W at 120 hours
0000Z (Aug 21) GFS Model Run...
**For Tropical Storm Gert... dissipates just northeast of the northern Lesser Antilles at 42 hours
**For Tropical Storm Emily... continues west-northwest to 24N-50.5W through 60 hours while weakening to a broad remnant low... while continuing north the remnant low consolidates into a compact tropical cyclone near 35.5N-50W by 120 hours
**For Tropical Storm Franklin... degenerates into a broad remnant low in the south-central Caribbean near 12.5N-71.5W through 30 hours... northeast side of the broad remnant low consolidtes into a compact tropical cyclone just south of the Dominican Republic by 45 hours... compact tropical cyclone crosses through the Dominican Republic through 60 hours... subsequently the tropical cyclone curves northeast and eastward while strengthening into a strong hurricane that reaches 23.5N-63W at 120 hours
**For area of interest #22... north side of tropical wave becomes a tropical cyclone offshore of the Texas/Mexico border at 30 hours... makes landfall just north of the border at 36 hours... inland remnant low continues west-northwestward across the Texas/Mexico border region and dissipates near 29.5N-101.5W at 54 hours
**For area of interest #23... passes through the Republic of Cabo Verde Islands over the next 9 hours as a broad tropical low... develops into a tropical cyclone near 17.5N-38W at 78 hours... tropical cyclone strengthens into a strong hurricane that reaches 21N-42.5W at 120 hours
1800Z (Aug 20) NAVGEM Model Run...
**For Tropical Storm Gert... dissipates just east of the northern Lesser Antilles and near 17.5N-60W at 36 hours
**For Tropical Storm Emily... continues west-northwest to 22N-48.5W through 54 hours while weakening to a broad remnant low... remnant low dissipates near 26N-55W through 120 hours while in between Franklin to the west-southwest and AOI #23 to the southeast.
**For Tropical Storm Franklin... reaches the central Caribbean near 15N-71W at 36 hours after which time it turns northward... passes through the Dominican Republic through 60 hours and then just east of the eastern Bahamas through 72 hours while beginning to intensify... curves eastward and reaches 24.5N-66W as a large and intense hurricane.
**For area of interest #22... north side of tropical wave organizes into western Gulf of Mexico tropical low just offshore of the Texas/Mexico border at 42 hours... makes landfall soon thereafter and dissipates inland over the southern Texas/Mexico border at 60 hours.
**For area of interest #23... passes through the Republic of Cabo Verde Islands over the next 12 hours as a broad tropical low... strengthens into a tropical cyclone near 15.5N-33.5W at 60 hours... tropical cyclone continues west-northwest to 20N-42.5W through 120 hours while strengthening into an intense hurricane
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