*******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.*********
...UPDATE...WEDNESDAY NOVEMBER 6 2024 1:59 PM EDT...
Satellite imagery of intensifying Hurricane Rafael. The left image was taken when Rafael became a category 1 hurricane centered over the eastern Cayman Islands last evening... right image was taken more recently while Rafael was a top-end category 2 hurricane intensifying further to category 3 status:
Rafael has exceeded previous intensity forecasts... likely while its core produced enough latent heat release and associated warm core upper ridging that is fending off southwesterly vertical shear that lies just to its west. As of 1 PM EDT Rafael was centered at 22N-82.3W... in between the Isle of Youth and mainland western Cuba... or just south of the previous track forecast... and had reached category 3 major hurricane status with maximum sustained winds of 115 mph and 956 mb minimum central surface pressure:
(1) In the hours ahead a swath of mainland western Cuba will experience the powerful and life-threatening hurricane-force winds and coastal storm surge in Rafael's core... evacuate from the coastal surge if told to do so by local government.... and be prepared to shelter to an interior room when the winds arrive. For the remainder of western Cuba affected by the outer bands of the hurricane surrounding the core... tropical storm conditions (heavy rainfall with flash flood potential... coastal surf... and gusty winds) will occur. Due to the wall of southwesterly upper winds just west of the hurricane... the outer bands are lopsided to the east of the core and reach into central Cuba... as such central Cuba will continue to see periods of heavy rainfall and flash flooding potential for the remainder of today.
(2) The Cayman Islands are also covered by the outer eastern bands of Rafael... and as such will continue to see periods of heavy rainfall and flash flooding potential for the remainder of today.
(3) Impacts from Rafael have ended for Jamaica and southwestern Haiti.
(4) For south Florida and the Keys... even though the hurricane is now carrying a slightly larger but also stronger than expected wind field... the long-range track has also shifted more west and away in alignment with what was the western-outlier ECMWF model. Therefore the outlook for this region for tonight looks the same (gusty winds... coastal surf... and heavy rainfall possible for the Keys... with the primary impact to the far southern Florida peninsula being more limited to possible bands of heavy rainfall).
(5) Weekend impacts to southeastern Louisiana... southern Mississippi... southern Alabama... and western Florida panhandle have become less likely with the recent shift in the computer model track consensus.
...TUESDAY NOVEMBER 5 2024 12:56 PM EDT...
The Atlantic tropics remain busy for early November with the following systems in progress:
(1) See Tropical Storm Rafael section below for the current central Caribbean tropical storm which is brining impacts to Jamaica and southwestern Haiti... and will bring impacts to Cuba... the Cayman Islands... south Florida including the Keys... and possibly southeastern Louisiana... southern Mississippi... southern Alabama.. and the western Florida panhandle.
(2) See area of interest #48 section below for a tropical low with development potential that is expected to materialize just north of the Caribbean Islands and zoom west into the Bahamas and south Florida through day 5.
(3) Note that the upper-level vortex that triggers area of interest #48 is expected to retrograde west across the northern Caribbean. As the upper vortex begins to collapse from its prolonged isolation from high-latitude cold air... while reaching the northwestern Caribbean in about a week from today... the expanding upper outflow that occurs in the south-central Caribbean in the wake of the collapsing upper vortex could help trigger yet another south-central Caribbean tropical disturbance in the wake of Rafael and area of interest #48 in the days ahead. Will add a new area of interest in the south-central Caribbean in future updates if needed.
TROPICAL STORM RAFAEL... Within the east side of the broad tropical low in the central Caribbean... tropical cyclone formation occurred approximately 24 hours ago (as of the time of this writing) when aircraft recon spotted a well-defined closed rotation at tropical depression strength... and this system was upgraded to tropical depression eighteen at the time. The surface rotation was west of my previous forecast track while on the west edge of the spiral thunderstorm bands and mid-level rotation instead of underneath those features. With time the spiral bands and mid-level rotation became aligned with the more western surface center... and so this system remains west of my previous forecast. The alignment also allowed this system to become better organized and strengthen to Tropical Storm Rafael by yesterday afternoon... and since then the tropical storm has steadily intensified to a higher-end tropical storm with 60 mph maximum sustained winds as of this writing. In addition to the stacking of the surface and mid-level structure... strengthening has also been allowed to occur due to dropping wind shear levels as the upper vortex that was previously over eastern Cuba has since retrograded westward and away toward the east coast of the Yucatan peninsula under the influence of the current eastern US upper ridge. However the intensification has not been as fast as I previously expected perhaps as the more west initial position of Rafael places it closer to the retrograding upper vortex which appears to be blocking the western outflow of the tropical storm... as evidenced by the satellite appearance showing less spiral thunderstorm bands west of center. In addition the 10 AM EDT NHC advisory mentioned a slot of dry air which has wrapped into the core from the west per microwave satellite imagery... despite water vapor imagery showing an abundance of moist air to the west of Rafael (https://cdn.star.nesdis.noaa.gov/GOES16/ABI/SECTOR/taw/08/1800x1080.jpg) perhaps there is still some dry air just west of the tropical storm associated with the sinking motion induced by the convergence at the core and west side of the Yucatan-area upper vortex. Despite the more west initial position and weaker intensity... my 24-hour forecast point remains almost the same as previous while calling for the same intensity at nearly the same location as (1) the models show that the flow between the east sides of the Yucatan-area upper vortex and remainder western part of the central Caribbean tropical low and southwest side of the current surface ridge which recently moved offshore into the Atlantic will still funnel Rafael to the just about the same 24-hour position as I showed before... and (2) I initially expected Rafael to acquire high-end category 1 strength in the next 12 hours while being further east away from the disrupting upper vortex then weaken to 85 mph maximum sustained winds by 24 hours as it then neared the upper vortex... however now it simply appears that Rafael will reach about the same intensity by 24 hours as it continues its slower strengthening rate. Despite the updated model guidance being very close to my previous forecast track... note that my updated 24-hour position is nudged west of my previous to acknowledge some of the initial more west position.
For the longer-range beyond 24 hours... with the exception of the western outlier ECMWF... the global models have come into good agreement on Rafael's track as it interacts with the current surface ridge that recently moved offshore into the Atlantic from the eastern US... the upper ridge currently over the eastern US which will also soon move offshore... and pair of upper troughs to eject from western North America. The divergence zone of the first of the two troughs (now currently over the central US and central Canada) will generate a narrow ridge weakness in the vicinity of the US east coast while its convergence zone produces a new surface ridge over the eastern US. Noting the narrow ridge weakness closes quickly as the first of the two troughs lifts northeastward and away due to the strength of the offshore-moving upper ridge... and instead of turning north into the short-lived weakness the models (except the ECMWF) are now in agreement on Rafael simply continuing northwestward toward the waters offshore of southeastern Louisiana while pushed along by the new eastern US surface ridge and old offshore Atlantic surface ridge (meanwhile the western outlier ECMWF pushes Rafael into the southwestern Gulf of Mexico while showing a stronger version of the new steering eastern US surface ridge). Toward day 5 a surface central US frontal system is expected to be generated by the divergence zone of the second of the two upper troughs ejecting from western North America... my current forecast track shows this frontal system turning Rafael north the northeast into the southeastern US from southeastern Louisiana by day 5 (meanwhile noting the NHC keeps Rafael offshore of southeastern Louisiana through day 5 while giving more weight to the western outlier ECMWF). Regarding long-range intensity... after 24 hours westerly shear is expected to re-increase as the remains of the Yucatan-area upper vortex are slung northeast closer to Rafael by the first of the two ejecting upper troughs from western North America. However today's 0600Z GFS shows less shear at 48 hours and a potential drop in wind shear by 72 hours while more quickly building a new warm core upper ridge in the central Gulf of Mexico generated by warm southerly flow ahead of the aforementioned developing central US surface frontal system. With my current forecast track along the north side of the central Gulf upper ridge... there will still be some westerly shear from 24 hours all the way till landfall time with southeastern Louisiana... however I have acknowledged today's 0600Z GFS by slowing the weakening rate in my updated forecast. I also support a slowed weakening rate as late as 96 hours when stronger westerly shear could be imparted by the incoming second of the two upper troughs ejecting from western North America... because of potential upper divergence between the northwest side of the central Gulf upper ridge and ahead of the incoming upper trough which could help support Rafael's surface low pressure field. Noting after 48 hours the 0600Z GFS suggested Rafael could slow down its northwest pace while a potentially stronger/taller version of Rafael gets dragged by the upper westerlies. Therefore despite a west nudge in my short-term forecast track... I am then re-aligned with my previous forecast track by 72+ hours due to my raised long-term intensity projection which could indeed allow Rafael to be stronger/taller enough to have its forward progressed slowed.
The following is the currently expected timing of tropical cyclone conditions (gusty winds with damage potential… coastal surf… and heavy rainfall):
(1) Tropical storm conditions are currently covering Jamaica as of this writing... and will continue for much of today until Rafael continues northwest and away. Due to the west adjusted short-term forecast track impacts to southwestern Haiti... which are occurring today... will be limited to heavy rainfall.
(2) Tropical storm to hurricane force conditions are expected across the Cayman Islands by tonight... and are expected to be most severe for the eastern islands where the center of circulation is expected to pass through.
(3) Due to the west adjusted forecast track... impacts to eastern Cuba... which will occur by tonight... are expected to be limited to heavy rainfall... with coastal surf possible for the south-facing coast.
(4) High chance of tropical storm to hurricane force conditions... central and western Cuba... by tomorrow.
(5) Tropical storm conditions are possible for the Florida Keys tomorrow. Further east... for the far southern Florida peninsula... the primary impact is expected to be bands of heavy rainfall.
(6) Interests across southeastern Louisiana... southern Mississippi... southern Alabama... and western Florida panhandle should monitor the progress of Rafael as tropical storm conditions are possible as soon as late Friday through Saturday.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1200Z Nov 5)... 60 mph maximum sustained wind tropical storm centered just west of southwestern Jamaica at 17.8N-78.6W
IOH 24 Hr Forecast (1200Z Nov 6)... 85 mph maximum sustained wind hurricane centered just offshore of western Cuba's south coast at 22.5N-82.5W
IOH 48 Hr Forecast (1200Z Nov 7)... 70 mph maximum sustained wind tropical storm centered in the southeastern Gulf of Mexico at 25N-85.5W
IOH 72 Hr Forecast (1200Z Nov 8)... 65 mph maximum sustained wind tropical storm centered offshore of southeastern Louisiana at 27.5N-89W
IOH 96 Hr Forecast (1200Z Nov 9)... 60 mph maximum sustained wind tropical storm centered over far southeastern Louisiana at 29N-89.5W
IOH 120 Hr Forecast (1200Z Nov 10)... Remnant frontal low centered over the northern Alabama/Georgia border at 33.8N-85.5W
*****National Hurricane Center (hurricanes.gov) official forecast as of 10 AM EDT*************************
Landfall (0000Z Nov 6)... 75 mph maximum sustained wind hurricane centered over the eastern Cayman Islands at 19.4N-79.9W
Peak Strength (0000Z Nov 7)... 90 mph maximum sustained wind hurricane centered on the north coast of western Cuba at 23.2N-83.1W
5-Day Position (1200Z Nov 10)... 50 mph maximum sustained wind tropical storm centered just offshore of southeastern Louisiana at 28N-90.5W
AREA OF INTEREST #48... Due to the force of the current eastern US upper ridge... some of the southwestern vorticity tied to the current north Atlantic upper trough has become cut-off from the rest of the trough and is diving south toward the northeastern Caribbean Islands. The divergence zone of the upper vorticity is currently producing scattered showers and thunderstorms north-northeast of the northern Lesser Antilles. In the next 36 hours the upper vorticity is expected to evolve into an upper vortex centered over the northeastern Caribbean Islands whose northeastern divergence zone is expected to trigger a tropical low north of the islands and along 20N latitude. Beyond that time the upper vortex retrogrades west to west-northwest across the northern Caribbean while moving around the south then southwest side of the eastern US upper ridge which shifts offshore during the forecast period. This will place the tropical low in deep-layer easterlies between the north side of the retrograding upper vortex... south side of the offshore-moving upper ridge... south side of the current surface ridge which recently moved offshore into the Atlantic from the eastern US... and south side of a new surface ridge to build over the eastern US which will also be moving offshore by day 5. The tunnel of deep-layer easterlies is expected to push the tropical low briskly west... followed by more of a west-northwest angle toward the latter part of the 5-day period while rounding the southwest side of the offshore-moving upper ridge and also the southwest side of the aforementioned surface ridge that moves offshore on day 5. Therefore this tropical low is likely to swing across the Bahamas and into the south Florida peninsula and the Keys by days 4 and 5. The tropical low has potential to develop into a tropical cyclone due to low shear and upper outflow on the south side of the upper ridge... assuming the retrograding upper vortex to the south does not impinge on this system too much. In this update cycle the usually aggressive CMC model is the only model developing this system... while the GFS and NAVGEM at least show a tropical low with a closed surface circulation. While acknowledging the GFS at least showing a tropical low... which is among the more respected global models... my peak odds of tropical cyclone formation are a little higher than the NHC's low 20% as of this writing.
Regarding impact to land areas... the northern Caribbean Islands are not likely to see much rainfall from this area of interest as the aforementioned upper vortex tracks over the islands and keeps activity suppressed with a lack of upper divergence at its core. Periods of heavy rainfall are possible across the Bahamas by Saturday and south Florida and the Keys by Sunday... with gusty winds and coastal surf also possible should tropical cyclone formation occur... and interests here should monitor the progress of this area of interest in the days ahead.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Nov 6)... 0% chance of tropical cyclone formation (northeast of the northern Lesser Antilles near 20N-60.5W)
IOH 48 Hr Outlook (1200Z Nov 7)... 10% chance of tropical cyclone formation (northeast of the Virgin Islands near 20N-63.5W)
IOH 72 Hr Outlook (1200Z Nov 8)... 30% chance of tropical cyclone formation (offshore of the northern Dominican Republic coast near 21N-69.5W)
IOH 96 Hr Outlook (1200Z Nov 9)... 30% chance of tropical cyclone formation (western islands of the southeastern Bahamas near 21.5N-74W)
IOH 120 Hr Outlook (1200Z Nov 10)... 30% chance of tropical cyclone formation (just offshore of southeast Florida near 24N-80W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 7 AM EDT*************************
Formation chance through 48 hours… 0%
Formation chance through 7 days… 20%
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
0000Z (Nov 5) CMC Model Run...
**For Tropical Storm Rafael... center passes just offshore of SW Jamaica at 12 hours then over the eastern Cayman Islands at 18 hours... strengthens while continuing northwest into western Cuba through 36 hours... holds peak strength while passing just west of the Florida Keys between 42 and 48 hours after which time weakening begins... makes landfall over SE Louisiana at 102 hours as a remnant low shortly after which time it loses identity along cold front of incoming central US frontal system.
**For area of interest #48... cut-off upper vorticity in the western Atlantic settles over the NE Caribbean Islands through 36 hours where its divergence zone produces a surface trough just east of the Lesser Antilles... north apex of the surface trough becomes a surface low north of Puerto Rico at 72 hours then a small tropical cyclone centered just NNW of Puerto Rico by 78 hours... without strengthening the small low end tropical cyclone proceeds into the central Bahamas by 114 hours... then western Bahamas by 126 hours... then the southern tip of the Florida peninsula by 138 hours... afterwards weakens to a surface trough in the eastern Gulf of Mexico.
**South part of surface trough associated with AOI #48 proceeds west across the Caribbean and evolves into a broad tropical low SW of Jamaica by 168 hours
0000Z (Nov 5) ECMWF Model Run...
**For Tropical Storm Rafael... center passes just offshore of SW Jamaica at 12 hours then over the eastern Cayman Islands at 24 hours... while gaining hurricane strength moves into western Cuba by 42 hours and proceeds to turn more west into the south-central Gulf of Mexico waters just north of the Yucatan peninsula through 84 hours... while continuing more slowly west into the southwestern Gulf of Mexico begins to weaken and becomes a remnant low centered near 23N-96W by 168 hours
**For area of interest #48... no development shown
0600Z (Nov 5) GFS Model Run...
**For Tropical Storm Rafael... center passes just offshore of SW Jamaica at 6 hours while strengthening further into a compact hurricane... compact hurricane continues NW into the eastern Cayman Islands by 18 hours... western Cuba by 33 hours... then just west of the Florida Keys by 48 hours... continues NW then north into the waters just offshore of SE Louisiana and Mississippi through 105 hours while weakening to a tropical storm with the center making landfall at the AL/MS border at 111 hours while weakening further to a tropical depression while drifting NE in track... inland remnant low then loses identity over east-central Alabama at 123 hours while merging with cold front associated with incoming central US frontal system
**For area of interest #48... cut-off upper vorticity in the western Atlantic settles over the NE Caribbean Islands through 36 hours where its divergence zone produces a broad surface trough just east of the Lesser Antilles... north apex of the surface trough proceeds to evolve into a multi-center tropical low sliding across the Virgin Islands and Puerto Rico through 60 hours... tropical low develops a better-defined singular center just offshore of the north-facing Dominican Republic coast by 75 hours and proceeds into the southeastern Bahamas by 93 hours... tropical low reaches the south tip of the Florida peninsula by 129 hours and proceeds to drift slowly northwest in the waters offshore of the southwestern Florida peninsula through 168 hours
**South part of surface trough associated with AOI #48 proceeds west across the Caribbean and evolves into a broad tropical low centered near 15N-80W by 168 hours
0600Z (Nov 5) NAVGEM Model Run...
**For Tropical Storm Rafael... center passes just offshore of SW Jamaica at 6 hours then over the eastern Cayman Islands at 18 hours... while strengthening continues NW into western Cuba by 36 hours and passes just west of the Florida Keys by 48 hours... while weakening to a lower-end tropical storm continues NW then north into southeastern Louisiana by 114 hours... inland remnant low then curves northeast into NW Alabama through 138 hours where it loses identity while merging with cold front associated with incoming central US frontal system
**For area of interest #48... cut-off upper vorticity in the western Atlantic settles over the NE Caribbean Islands through 48 hours where its divergence zone produces a broad surface trough just east of the Lesser Antilles... north apex of the surface trough proceeds to become a tropical low that moves WNW into the waters east of the central Bahamas through 108 hours... tropical low then continues into the western Bahamas by 138 hours then toward the east-central coast of Florida through 168 hours
**Outflow of current central tropical Atlantic upper ridge produces a tropical low near 10N-46W at 60 hours... tropical low proceeds west-northwest into the central Lesser Antilles through 156 hours as it becomes a tropical cyclone... tropical cyclone centered in the eastern Caribbean near 15N-63W at 168 hours
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