*******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.*********
...UPDATE...THURSDAY OCTOBER 10 2024 3:00 PM EDT...
The surface and upper air charts valid for October 9 are now included below. Full discussions on areas of interest #40 and #41 are also now included below. In addition... the following events have occurred since the October 9 update:
(1) Milton's center made landfall just south of Tampa Bay Florida as of 8:30 PM EDT October 9... landfall stats were 120 mph maximum sustained winds with 954 mb minimum surface pressure. By 5 AM EDT early today the center proceeded eastward into the Atlantic from the east coast of Florida while packing 85 mph maximum sustained winds. As of this writing Milton is centered north of the northwestern Bahamas. A surface cold front driven by the currently developing Atlantic Canada frontal cyclone has been driven south into Milton... and as Milton wrapped in the cooler drier air behind the front most of the thunderstorm activity near the surface circulation center has dwindled (ongoing westerly wind shear which has been pushing the thunderstorms and associated latent heat release east of the center has also helped the cooler drier air in taking over). As a result the NHC as of 2 PM EDT has declared Milton a non-tropical remnant frontal cyclone... but still packing maximum sustained winds of 75 mph. Coastal surf affecting the Florida... southeastern United States... and northwestern Bahamas will be gradually dwindling with time as ex-Milton continues east.
(2) Leslie in the open central Atlantic attained a peak category 2 strength of 105 mph maximum sustained winds overnight... however through this morning has become less organized as northerly wind shear has overspread the hurricane. As of 11 AM EDT Leslie has weakened to 90 mph maximum sustained winds.
...WEDNESDAY OCTOBER 9 2024 4:22 PM EDT...
This post is initially released without full discussion on areas of interest #40 and #41 due to the urgent situation of Milton approaching Florida from the eastern Gulf of Mexico... to get this post published as soon as possible (areas of interest #40 is a tropical wave of low pressure nearing the west coast of Africa which is expected to approach the Republic of Cabo Verde Islands by Friday while possibly developing... and area of interest #41 is the current western Atlantic surface low that will be passing just south of Bermuda over the next day... brining coastal surf to Bermuda regardless of tropical cyclone formation or not... and in recent hours tropical cyclone formation appears less likely as the system has become less organized under westerly shear).
See Hurricane Leslie and Hurricane Milton sections below for more information on current pair of active tropical cyclones in the Atlantic basin. Major Hurricane Milton is the most pressing situation as it brings severe to life-threatening weather conditions across the Florida peninsula for the remainder of today. In addition... noting that over the next week a currently developing Atlantic Canada frontal cyclone... followed by yet another frontal cyclone that will take its place... will drive surface cold fronts toward the western Caribbean. Although the upper troughs associated with the forecast frontal cyclones drives most of the current northern Caribbean Islands upper anticyclone into a trans-Atlantic journey... a remainder southwestern lobe of the upper anticyclone hangs over the central and western Caribbean in the days ahead. Therefore it is possible the combination of thunderstorms triggered by the decaying surface fronts... and low shear/upper outflow of the upper anticyclonic flow over central and western Caribbean... produces a tropical disturbance in the central/western Caribbean region that may bear watching for tropical development in approximately one week from today.
HURRICANE LESLIE... Leslie and a wave of upper vorticity to its southwest have continued generally west while pushed around the southwest quadrant of the eastern Atlantic surface ridge and also the southwest quadrant of an eastern Atlantic cell of upper ridging. The west track of Leslie has had an ongoing north component due to the southerly component of flow on the east side of the upper vorticity wave and southwest side of the eastern Atlantic surface ridge. The storm is slightly west of the previous forecast and so my updated short-term track forecast is adjusted accordingly. Leslie continued to weaken through yesterday due to southerly shear on the east side of the upper vorticity wave and dipped to a minimum strength of 70 mph maximum sustained winds. Then while finding a pocket of favorable upper winds north of the wave of upper vorticity late yesterday... Leslie finally began to re-intensify as I previously anticipated and has reached 85 mph maximum sustained winds as of today's 11 AM EDT advisory... albeit the re-intensification started later than I previously thought. Leslie has also gotten lucky as it will remain under favorable low shear and outflow for a little longer than previously thought while the gap between the wave of upper vorticity to the south and passing north Atlantic upper trough is larger than previously forecast... and Leslie is likely to strengthen more in the next 12 hours. To the west of Leslie... the current eastern Canada upper trough has knocked the warm core upper anticyclone/ridge that was over Milton eastward... and the southeast quadrant of the fast-approaching upper anticyclone should begin northeasterly shear over Leslie between 12 and 24 hours. Therefore I forecast Leslie to peak in intensity at 12 hours... then quickly weaken to a minimal hurricane by 24 hours under the burst of northeasterly shear. Noting the eastern convergence zone of the anticyclone may produce some blocking surface ridging to the west of Leslie… which is why the hurricane may slow down its northwest track in the next 24 hours. By 48 hours the eastern Canada upper trough contributes to a strong Atlantic Canada surface frontal cyclone. This frontal cyclone should proceed to weaken any blocking surface ridge west of Leslie and turn Leslie increasingly north then northeast through 72 hours. Noting the current long-term GFS/ECMWF consensus has trended toward what I previously forecasted albeit a little towards the south... and so my updated long-term track is nudged in that direction. At around what is currently the 48 hour mark I show yet another burst of quick re-strengthening when Leslie exits the northeasterly shear and enters low shear under the core of the upper anticyclone... then between 48 and 72 hours I currently expect Leslie to enter much higher westerly shear on the north side of the anticyclone and transition into a non-tropical frontal cyclone while a cold front driven by the offshore-moving Atlantic Canada frontal cyclone gets pushed into Leslie. It is interesting to note that the GFS/ECMWF consensus has Leslie keeping tropical status... perhaps while now keeping Leslie just south of the cold front while simultaneously the east-northeast acceleration of Leslie toward the Azores would be fast enough to mitigate the westerly shear. If this indeed comes to fruition I will be extending my forecasts for Leslie beyond October 12 in future updates. Regardless of whether Leslie is tropical... or remains a frontal cyclone supported by divergence between the north side of the upper anticyclone and out ahead of the offshore-moving Atlantic Canada surface frontal cyclone/upper trough... Leslie now has an increased chance to bring swells to the shores of the Azores by Sunday. For the long range... the GFS/ECMWF consensus has the east side of the upper anticyclone settle into the mid-latitudes of the eastern Atlantic... with Leslie weakening to a fading remnant low while diving southeast around the suppressive eastern convergence zone of the upper anticyclone. Therefore the surface circulation of Leslie and its gusty winds are expected to pass just south of the Azores... with impacts to the Canary Islands early next week being minimal as Leslie undergoes its southeast-diving fading phase.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Oct 9)... 85 mph maximum sustained wind hurricane centered in the central Atlantic at 21.7N-48.4W
IOH 24 Hr Forecast (1800Z Oct 10)... 75 mph maximum sustained wind hurricane centered in the central Atlantic at 24N-50W
IOH 48 Hr Forecast (1800Z Oct 11)... 90 mph maximum sustained wind hurricane centered in the central Atlantic at 27.5N-50W
IOH 72 Hr Forecast (1800Z Oct 12)... Remnant frontal cyclone centered in the central Atlantic at 32N-45W
*****National Hurricane Center (hurricanes.gov) official forecast as of 11 AM EDT*************************
Peak Strength (0000Z Oct 10)... 100 mph maximum sustained wind hurricane centered in the central Atlantic at 22.5N-49.2W
5-Day Position (1200Z Oct 14)... 35 mph maximum sustained wind remnant frontal low centered just south of the eastern Azores at 35.9N-26.7W
MAJOR HURRICANE MILTON... Satellite image of Hurricane Milton on 1956Z Tuesday October 8 while re-gaining a second category 5 peak in the southeastern Gulf of Mexico (peak measured 165 mph maximum sustained winds with 902 mb minimum central surface pressure at 7 PM EDT Tuesday October 8):
As expected Milton has curved northeastward across the southeastern Gulf of Mexico and toward the Florida peninsula while guided by approaching upper vorticity that is now over the southeastern US and northern Gulf of Mexico. After completing an eye wall replacement cycle Tuesday morning... the hurricane re-intensified into a category 5 peak Tuesday night while the upper southwesterly flow ahead of the upper vorticity boosted the northern outflow of the hurricane. My previous intensity forecast performed quiet well while Milton peaked at 165 mph maximum sustained winds exactly as predicted... the only difference is it happened a few hours earlier than I expected. Today Milton has moved directly into the stronger upper southwesterly winds and accordingly looks increasingly disheveled. The onset of the southwesterly shear has caused Milton to weaken through the still-severe category 4 wind scale today... and Milton has weakened a little faster than my previous forecast. The track has also been a little south of my previous forecast as the upper southwesterly flow has come in a little more westerly and less southerly than previously thought... which has also increased the severity of the shear which is why Milton is probably weakening a little faster than I previously thought. The updated more east and less north track gives a little less time over water... which is why I still expect a minimal category 3 landfall for tonight despite the slightly faster weakening rate.
After landfall... the steering upper vorticity is coaxed into a more SW/NE tilt while dragged by eastern Canada upper trough's east shift into Atlantic Canada. This results in a further increase in westerly wind shear and deflection of the track to an even more east and less north angle. And by 48 hours a surface ridge builds north of Milton under the western convergence zone of the Atlantic Canada upper trough... slowing the east progress of Milton which further increases the shearing effect of the upper westerlies.. at this point I forecast Milton to be knocked down to a tropical depression. The eastward forward speed is likely to increase by day 3 as Milton escapes the surface ridge... however the speed of the shearing upper westerlies will still be great enough to weaken the tropical cyclone to a remnant low by then. Albeit I have nudged down the day-3 eastward forward speed as the models have trended with more of a northward lift to the Atlantic Canada upper trough which slows down the steering/shearing upper westerlies a little bit.
Regarding impact to land areas:
(1) Interests across the Florida peninsula should have completed preparations for potentially severe damage from strong hurricane force winds and coastal surge to arrive in the hours ahead... the worst of which will be the on the west-facing coast... but also note significant impacts are also expected across inland areas and the east-facing coast as Milton would be moving quickly through the area and not have much time to weaken after the west coast landfall. Listen to your local news media and local government officials for more information on current happenings with Milton and how to stay safe. Also noting the directional wind shear between surface southerlies on Milton's southeast quadrant is in directional shear with respect to the aforementioned upper southwesterlies steering and shearing Milton... this shear is aiding in the generation of tornado-warned thunderstorm cells across central and southern Florida... please monitor local news media coverage and be prepared to shelter during tornado warnings in your area if you are currently in this region.
(2) The heavy rain/gusty winds associated with Milton's outer bands stayed north of western Cuba... however interests here will see coastal surf over the next several hours.
(3) The Florida Keys are also seeing coastal surf and outer heavy rainfall bands that could generate some gusty winds... these weather conditions will continue for the rest of today.
(4) The northwestern Bahamas will also see coastal surf... along with possible outer heavy rainfall bands bringing gusty winds. These impacts are expected by tomorrow.
Update as of 4 PM EDT... Milton has weakened to a still-dangerous category 3 hurricane with 125 mph maximum sustained winds while continuing to move toward the west coast of Florida.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Oct 9)... 130 mph maximum sustained wind major hurricane centered offshore of southwestern Florida at 26.3N-84W
IOH 12 Hr Forecast (0600Z Oct 10)... 105 mph maximum sustained wind hurricane centered inland and just east-southeast of Tampa Bay Florida at 27.5N-82W
IOH 24 Hr Forecast (1800Z Oct 10)... 60 mph maximum sustained wind tropical storm centered north of the northwestern Bahamas at 28.5N-77W
IOH 48 Hr Forecast (1800Z Oct 11)... 35 mph maximum sustained wind tropical depression centered in the western Atlantic at 29N-74W
IOH 72 Hr Forecast (1800Z Oct 12)... Remnant low centered in the western Atlantic at 29N-69W
*****National Hurricane Center (hurricanes.gov) official forecast as of 11 AM EDT*************************
Landfall (0000Z Oct 10)... 125 mph maximum sustained wind major hurricane centered just south-southwest of Tampa Bay Florida at 27N-83W
5-Day Position (1800Z Oct 12)... 35 mph maximum sustained wind frontal low centered in the central Atlantic at 32.8N-55.9W
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
0000Z (Oct 9) CMC Model Run...
**For Hurricane Leslie... weakens to a tropical storm near 24.5N-50W through 48 hours then a remnant low near 29.5N-47.5W at 72 hours... remnant low progressively turns east-northeast... east... then east-southeast and weakens to a surface trough west of the Canary Islands through 168 hours
**For Major Hurricane Milton... makes landfall just south of Tampa Bay Florida between 30 and 36 hours while progressively weakening... passes just north of the northwestern Bahamas by 48 hours as a sheared tropical storm and then transitions into an elongated remnant low east-northeast of the northwestern Bahamas by 60 hours... the gradually weakening elongated remnant low passes just southeast of Bermuda through 114 hours and loses its identity near 33N-52.5W by 144 hours
**For area of interest #40... passes over the Republic of Cabo Verde Islands by 54 hours as a tropical low... subsequently the tropical low weakens to a trough which reaches 19.5N-41.5W by 168 hours
**For area of interest #41... passes just southeast of Bermuda through 30 hours... while becoming wrapped into Atlantic Canada frontal cyclone and supportive eastern divergence zone of its associated upper vorticity the frontal low proceeds to curve north and strengthen into a frontal cyclone between the southern tip of Greenland and Newfoundland through 72 hours... the frontal cyclone proceeds to whirl west then southwest into Newfoundland through 114 hours while undergoing typical post-mature decay phase underneath part of overhead upper vorticity that lacks upper divergence... the weakening frontal cyclone dissipates over Newfoundland by 120 hours
**Tail end of cold front driven by ex-Milton settles in the northwestern Caribbean through 120 hours... tail end of front transitions into broad tropical surface trough that moves west-northwest into the south-central Gulf of Mexico through 168 hours
0000Z (Oct 9) ECMWF Model Run...
**For Hurricane Leslie... weakens to a tropical storm near 27N-50W through 66 hours... continues east-northeast into the waters just southwest of the Azores through 126 hours while remaining a tropical storm... subsequently weakens to a fading remnant low that dives southeast into the waters just west of the Canary Islands through 168 hours
**For Major Hurricane Milton... makes landfall over Tampa Bay Florida at 36 hours and while retaining hurricane strength curves east into the waters north of the northwestern Bahamas through 54 hours... finally weakens to a sheared tropical storm that passes just south of Bermuda by 102 hours... weakens to a remnant low near 34N-49W by 156 hours... remnant low continues east-northeast to 36.2N-47.5W through 168 hours
**For area of interest #40... passes over the Republic of Cabo Verde Islands by 54 hours as a tropical low... subsequently the tropical low weakens to a trough which reaches 19.8N-40W by 150 hours... trough dissipates shortly thereafter
**For area of interest #41... passes just south of Bermuda in next 24 hours while becoming increasingly elongated... while becoming wrapped into Atlantic Canada frontal cyclone and supportive eastern divergence zone of its associated upper vorticity the frontal low proceeds to curve north and strengthen into a frontal cyclone between the southern tip of Greenland and Newfoundland through 72 hours... the frontal cyclone proceeds to whirl west then southwest into southern Labrador through 102 hours while undergoing typical post-mature decay phase underneath part of overhead upper vorticity that lacks upper divergence... the weakening frontal cyclone dissipates shortly thereafter
1200Z (Oct 9) GFS Model Run...
**For Hurricane Leslie... weakens to a tropical storm near 28.5N-50W through at 60 hours... continues east-northeast into the waters just southwest of the Azores through 111 hours while remaining a tropical storm... subsequently weakens to a fading remnant low/trough that dives southeast into the southern Canary Islands through 168 hours
**For Major Hurricane Milton... makes landfall just south of Tampa Bay Florida at 15 hours... while gradually weakening to a tropical storm curves east and passes just north of the northwestern Bahamas by 36 hours... transitions into an elongated remnant low east-northeast of the northwestern Bahamas by 72 hours... after current Atlantic Canada frontal cyclone moves into the north Atlantic another second frontal cyclone moves into Atlantic Canada in the longer range which curves the remnant low of Milton north into the northwestern Atlantic... remnant low of Milton loses identity ahead of cold front tied to the second Atlantic Canada frontal cyclone while positioned near 40N-54W at 159 hours
**For area of interest #40... passes over the Republic of Cabo Verde Islands by 48 hours as a tropical low... subsequently the tropical low weakens to a trough which reaches 16N-45.5W by 168 hours
**For area of interest #41... becomes a possible compact tropical cyclone just south of Bermuda by 15 hours... while continuing east-northeast into open central Atlantic loses identity along cold front driven into this system by Atlantic Canada frontal cyclone by 45 hours
**Tail end of cold front driven by ex-Milton settles in the northwestern Caribbean through 96 hours then central Caribbean by 135 hours... through 156 hours another cold front tail end is pushed into the central Caribbean by long-term Atlantic Canada frontal cyclone that interacts with ex-Milton... the decaying fronts evolve into a tropical low just east of Nicaragua and Honduras by 168 hours
1200Z (Oct 9) NAVGEM Model Run...
**Not available at above-mentioned source
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