*******Note that forecasts 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.*********
...SATURDAY NOVEMBER 9 2024 8:00 PM EDT...
The Atlantic tropics remain busy for November while still monitoring concurrent systems as follows:
(1) See Rafael section below for an update on the ongoing Gulf of Mexico tropical cyclone
(2) See area of interest #48 section below for a surface trough heading for the NW Bahamas and Florida peninsula. Noting this area of interests’ remnants… or the front that moves offshore from its current central US position… could evolve into a subtropical disturbance southeast of Bermuda while moving east across the west Atlantic during this upcoming week.
(3) See area of interest #49 section below for a currently emerging eastern Caribbean broad tropical low that could develop as it later slides into the central Caribbean
TROPICAL STORM RAFAEL... Satellite image of Hurricane Rafael reaching its second category 3 peak while in the south-central Gulf of Mexico as of 0610Z November 8. Since then wind shear has re-developed over the tropical cyclone and it has rapidly weakened to a tropical storm:
After being pushed west across the Gulf of Mexico along 25N latitude by the current eastern US surface ridge… Rafael is beginning to turn northwest toward the current central US frontal low. Over the last 24 hours westerly shear over the tropical cyclone has increased ahead of the arrival of the frontal low’s upper trough. Even though the shear levels are not yet high… Rafael has rapidly weakened from a category 2 to 3 hurricane as of yesterday to a lower-end tropical storm through today. Even though shear increases further in the next 24 hours… I hang on to Rafael as a minimal tropical storm due to potential split flow upper divergence between westerlies the north side of the current Gulf of Mexico upper ridge and southwesterlies ahead of the incoming upper trough.
The models have come into agreement on weighting the long-range forecast away from the passing central US frontal low/ upper trough and toward the southwestern Gulf of Mexico and associated Mexican coastline. As a result from 48 to 72 hours I then forecast Rafael to drift south along 94W longitude while coming under the influence of the Caribbean gyre of low pressure nearing from the east to be associated with area of interest #49. In the wake of the passing central US upper trough… a new upper ridge enters the Gulf of Mexico from northern Mexico… upper convergence and northerly shear from the east side incoming upper ridge should help weaken Rafael to a tropical depression in between 48 and 60 hours. Between 60 and 72 hours I hang on to Rafael as a tropical depression as shear begins to relax and upper outflow increases when the core of the upper ridge nears… then show Rafael re-intensify into a tropical storm by 96 hours. During this time the track could continue south under the influence of the Caribbean gyre of low pressure… or more west as a central/ eastern US surface ridge gains peak strength in the wake of the exiting central US frontal low/ upper trough. The 96-hour steering picture is more complicated by the fact that a re-strengthening Rafael at that time could become strong/tall enough to be influenced by m upper southerlies on the southwest side of the Gulf upper ridge that would counteract any south or west progress. Taking all of the above into consideration… I show Rafael drift slowly southwest in the 72 to 120 hour window (even though another frontal system slides across the north-central US around 120 hours… it passes too far north to influence Rafael and another surface ridge that fills in behind continues the southwest track of Rafael thru 120 hours). Between 96 and 120 hours I forecast Rafael to re-weaken to a tropical depression as what remains of the current central Caribbean upper vortex rounds the southwest corner of the Gulf upper ridge and overtops Rafael with a round of southwesterly shear.
Regarding impacts to land areas… in the next 24 hours sheared-off moisture from Rafael may contribute to periods of periods of heavy rainfall over southeast Louisiana… and coastal surf for the south-facing Louisiana coast is possible. Once Rafael reverses course and goes southwest… the potential for coastal surf shifts toward the coast of Mexico from Veracruz to the northwestern Yucatan peninsula by Tuesday through mid-week.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1200Z Nov 9)... 50 mph maximum sustained wind tropical storm centered over the central Gulf of Mexico at 25.2N-91.5W
IOH 24 Hr Forecast (1200Z Nov 10)... 40 mph maximum sustained wind tropical storm centered offshore of Louisiana at 27N-93W
IOH 48 Hr Forecast (1200Z Nov 11)… 35 mph maximum sustained wind tropical depression centered in the western Gulf of Mexico at 25N-94W
IOH 72 Hr Forecast (1200Z Nov 12)… 50 mph maximum sustained wind tropical storm centered in the southwestern Gulf of Mexico at 23N-94W
IOH 96 Hr Forecast (1200Z Nov 13)… 50 mph maximum sustained wind tropical storm centered in the southwestern Gulf of Mexico at 22.5N-95W
IOH 120 Hr Forecast (1200Z Nov 14)… 35 mph maximum sustained wind tropical depression centered offshore of northern Veracruz at 22N-96.5W
*****National Hurricane Center (hurricanes.gov) official forecast as of 4 PM EDT*************************
4-Day Position (1800Z Nov 13)… 30 mph maximum sustained wind dissipating remnant low centered in the western Bay of Campeche at 21N-95W
AREA OF INTEREST #48... Visible Satellite image of small low pressure spin developing east of the Bahamas and at the north apex of a surface trough as of 1800Z today:
A surface trough of low pressure passing north of the Caribbean Islands continues west toward the Bahamas while funneled in deep-layer easterly flow between deep-layer ridging to the north and a central Caribbean upper vortex to the south… and satellite imagery shows a small spin has developed at the north apex of the trough near 25N-71W (the spin was more apparent in visible satellite imagery before sunset… which showed the spiral banding better than infrared). The spin was added as a low pressure center in the most recent 1800Z NHC TAFB surface analysis. The deep-layer ridging has shifted west while the previous upper and surface ridges in the west Atlantic have been eroded by the southeast-diving upper trough from eastern Canada… with the ridging now associated with the current Gulf of Mexico upper ridge and eastern US surface ridge further west. Accordingly… recent nighttime infrared shows the thunderstorm are a bit sheared east of the small spin due to northwesterlies imparted by the east side of the Gulf upper ridge. However I have increase odds of tropical cyclone formation to 40% in this update as the small spin moves west into lower shear in the next 24 hours. By 48 hours westerly shear increases with the approach of the upper trough/surface front currently over the central US… combined with landfall with southeast Florida and expected merger with the surface cold front I drop offs of tropical cyclone formation to 0% (also noting the west track slows and bends more north in the 24 to 48 hours due to the flow ahead of the approaching surface front). The northwest Bahamas and southern Florida peninsula may see gusty winds and heavy rain from this system tomorrow through Monday.
Noting in the long-range the remnant frontal low of this system reverses east from Florida and into the waters southeast of Bermuda thru mid-week. The southern base of the front’s upper trough may become amplified enough to produce low enough shear and high enough upper divergence to potentially transform this system into a subtropical disturbance southeast of Bermuda. For now ending the outlook at 48 hours to see if the remnants of this disturbance keep their identity along the front… if not the possible long range subtropical disturbance would get a different area of interest number in future updates on this site.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Nov 10)... 40% chance of tropical cyclone formation (northwestern Bahamas near 25N-77W)
IOH 48 Hr Outlook (1800Z Nov 11)… 0% chance of tropical cyclone formation (Lake Okeechobee Florida near 26.5N-81W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 7 PM EDT*************************
Formation chance through 48 hours… 10%
Formation chance through 7 days… 10%
AREA OF INTEREST #49… The remainder southern portion of the surface trough associated with area of interest #48 was producing an axis of thunderstorms south of the Dominican Republic as of this past afternoon. A surface tropical wave of low pressure that passed through the central Atlantic… Lesser Antilles… and into the eastern Caribbean in recent days likewise was producing another axis of thunderstorms west of the Lesser Antilles this past afternoon. The two surface features appear to be merging into a broad eastern Caribbean tropical low… and the CIMSS 850 mb vorticity product suggests a low-level spin is already consolidating SSW of Puerto Rico (https://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). Although the axis of thunderstorms that was south of the Dominican Republic dissipated tonight… the axis that was west of the Lesser Antilles has grown in size and organization while increasingly co-locating with the vorticity signature SSW of Puerto Rico. Moreover upper-level winds become increasingly conducive for development with time as the central Caribbean upper vortex retrogrades west and away while weakening… which allows for increasing upper ridging with outflow over this disturbance. Therefore declaring a new area of interest for the Caribbean… the forty-ninth tracked on this site this year. Given the CIMSS 850 mb vorticity low-level spin and increasing thunderstorm
around it… I have already assigned a peak 30% chance of tropical cyclone for the 5-day period which is high for a new area of interest… and high for a disturbance not yet mentioned in the NHC outlook. Noting the west forward speed slows by days 3 and 4 due to the ridge weakness associated with the surface front that moves from its current central US position and into the offshore Atlantic waters just north of the Caribbean during the forecast period. Around or after day 5… this disturbance could gain an increased forward heading toward Central America while escaping the ridge weakness. Interests in Central America and Jamaica should be aware of this disturbance as it is expected to move in their proximity during this upcoming week.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Nov 10)... 0% chance of tropical cyclone formation (eastern Caribbean near 15N-69W)
IOH 48 Hr Outlook (1800Z Nov 11)… 20% chance of tropical cyclone formation (central Caribbean near 15N-73W)
IOH 72 Hr Outlook (1800Z Nov 12)… 30% chance of tropical cyclone formation (southeast of Jamaica near 15N-75W)
IOH 96 Hr Outlook (1800Z Nov 13)… 30% chance of tropical cyclone formation (south of Jamaica near 15N-77.5W)
IOH 120 Hr Outlook (1800Z Nov 14)… 30% chance of tropical cyclone formation (central Caribbean near 15N-80W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 7 PM EDT*************************
Not in the official outlook
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
0000Z (Nov 9) CMC Model Run...
**For Tropical Storm Rafael... quasi-stationary thru 48 hours then begins to move SW while weakening… dissipates while making landfall on the Bay of Campeche coast of Mexico at 138 hours
**For area of interest #48... surface trough moves WNW into the western Bahamas through 42 hours… makes landfall on the SE coast of Florida at 66 hours… turns NE while merging with surface front moving offshore of eastern US… the remnant frontal low then transitions into a surface cyclone SE of Bermuda at 126 hours which potentially gains subtropical characteristics… the surface cyclone then transitions into a more-elongated less tropical system while moving NE into the open central Atlantic
**For area of interest #49… South part of surface trough associated with AOI #48 and current SE Caribbean tropical wave merge into a broad tropical low centered SE of Jamaica at 78 hours… broad tropical low proceeds west toward Nicaragua/ Honduras border through 168 hours while becoming a possible tropical cyclone
0000Z (Nov 9) ECMWF Model Run...
**For Tropical Storm Rafael... drifts slowly west to 25N-48W thru 42 hours while weakening… turns SW into the Bay of Campeche through 90 hours while weakening further to a surface trough… surface trough dissipates while quasi-stationary in the Bay thru 126 hours
**For area of interest #48... surface trough moves west into the central Bahamas through 36 hours… continues into the waters between NW Bahamas and SE Florida through 60 hours… surface trough turns NE while merging with surface front moving offshore of eastern US and becomes a remnant frontal low near 30N-75W at 78 hours… remnant frontal low then dives ESE and transitions into a compact circular tropical cyclone near 26N-57.5W by 120 hours… on the same front a large frontal cyclone that retrogrades into Atlantic Canada develops to the north with the tropical cyclone taking a northbound cyclonic orbit around that feature… on the cyclonic orbit the tropical cyclone reaches the waters SW of Newfoundland by 168 hours while gradually transitioning into a frontal cyclone itself
**For area of interest #49… South part of surface trough associated with AOI #48 and current SE Caribbean tropical wave merge into a broad tropical low centered south of Jamaica at 66 hours… through 168 hours the broad tropical low drifts very slowly west toward Central America
0600Z (Nov 9) GFS Model Run...
**For Tropical Storm Rafael... quasi-stationary thru 48 hours while weakening… then moves SW then west while weakening further and dissipates at 132 hours while making landfall with northern Veracruz
**For area of interest #48... surface trough moves west into the central Bahamas through 24 hours… then west across central and western Cuba through 63 hours while losing identity to surface front moving offshore of eastern US to the north and area of interest #49 to the south
**For area of interest #49… South part of surface trough associated with AOI #48 and current SE Caribbean tropical wave merge into a broad tropical low over the south-central Caribbean at 42 hours… broad tropical low drifts slowly west and becomes a tropical cyclone just offshore of Nicaragua at 144 hours… the tropical cyclone continues into east-central Nicaragua where it becomes an inland remnant low by 168 hours
0600Z (Nov 9) NAVGEM Model Run...
**For Tropical Storm Rafael... moves WNW to 26N-94W through 36 hours where it then stalls… begins to move SW by 66 hours and weakens to a surface trough offshore of northern Veracruz by 114 hours… remnant trough dives south into the western Bay of Campeche where it dissipates by 132 hours
**For area of interest #48… no development shown
**For area of interest #49… current SE Caribbean tropical wave moves WNW toward the ridge weakness associated with dissipating area of interest #48 and becomes a tropical low offshore of the south Dominican Republic coast at 42 hours… while becoming a tropical depression moves WNW into SW Haiti through 84 hours… turns west into Jamaica as a tropical storm thru 114 hours…. drifts WSW into the waters between Jamaica and Central America through 168 hours while becoming a large and intense hurricane
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