*******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.*********
...TUESDAY JUNE 11 2024 1:03 PM EDT...
A surface trough of low pressure remains stationary over the Yucatan peninsula of southeastern Mexico... and has recently expanded northeastward across the eastern Gulf of Mexico and toward the Florida peninsula due to split flow upper divergence between the northwesterly flow across the northeast side of the regional tropical upper ridge and more westerly flow across the south side of the current eastern North America upper trough. A tropical disturbance has developed toward the Florida peninsula that is being monitored for signs of further development... this is the fourth tropical area of interest tracked on this site this year... see area of interest #4 section below for more details.
Elsewhere... the remainder southern portion of the Yucatan surface trough is expected to fester over the next few days while remaining supported by the outflow of the regional tropical upper ridge... and then eventually the divergence zone of the upper vorticity currently heading toward the southeastern United States and western Gulf of Mexico from its current north Texas position. Tropical development over the next 96 hours from this feature is not likely due to southwesterly shear associated with the incoming upper vorticity. Beyond that time the cut-off upper vorticity currently parked offshore of California and Mexico's Baja California peninsula will finally makes its way into the central US as an upper trough once the steering upper westerly flow finally increases across the central and western US when the current north Canada polar upper vortex and northeastern Pacific upper vortex eventually merge. The forecast long-term central US upper trough will help pull the shearing western Gulf upper vorticity northward and away... which may finally allow the lingering Yucatan surface trough to develop into an organizing western Gulf tropical disturbance in the 5 to 7 day window... particularly as the regional tropical upper ridge and supporting upper outflow expands in the wake of the retreating western Gulf upper vorticity. Will potentially be declaring another area of interest for the western Gulf of Mexico in future updates.
AREA OF INTEREST #4... Satellite animation and CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=) suggests an area of maximum spin has developed along the surface trough currently spanning the Yucatan peninsula and eastern Gulf of Mexico... in the vicinity of 26.5N-84.5W. See above intro section of this update for an explanation on how the surface trough has recently expanded across the eastern Gulf of Mexico. The National Hurricane Center has upgraded this disturbance to an area of interest for further development as multiple model runs suggest possible development after this system moves northeast across the Florida peninsula and into the waters offshore of the southeastern United States.
Over the next 24 hours this system is expected to continue northeast across the Florida peninsula and into the waters offshore of the southeastern United States in the flow ahead of the stalled surface front located just to the northwest... my 24 hour forecast position in the outlook below is based on the current trajectory this system is taking in satellite animation which should have the maximum spin move across Tampa Bay Florida later today... and makes sense with the upper wind forecast which shows the maximum supporting upper divergence being located near 29.5N-80W. Tropical cyclone formation is not expected during this period due to excess westerly vertical shear. From 24 to 48 hours this system is likely to meander as it becomes sandwiched between the Atlantic surface ridge to the east and incoming surface ridge to the northwest... however after 48 hours the surface ridge becomes eroded and replaced by an incoming surface cold front due to the divergence zone of a high-latitude cold upper trough (the cold upper trough materializes from the merger between the current western Canada upper trough... and some energy from the current north Canada polar upper vortex and northeastern Pacific upper vortex). Therefore the forecast track in my outlook below and model consensus is for a northeast acceleration after 48 hours in the flow ahead of the incoming surface cold front. Noting my forecast positions along the northeast acceleration angle toward where the forecast upper-level wind fields show maximum supporting upper divergence... which will primarily come from the upper vorticity that is currently approaching the southeastern US/western Gulf of Mexico from its current north Texas position. For the 48 to 72 hour window I pull odds of tropical cyclone formation above 0% as westerly wind shear potentially relaxes and upper divergence increases when the upper vorticity gains amplitude while merging with the aformentioned high-latitude upper trough and also due to upstream amplification of western US warm upper ridging (the upstream upper ridge initially sprouts from warm southerly flow ahead of the surface cold front that will hit this system around 96 hours... followed by warm southerly flow ahead of another surface frontal system that materializes over western North America under the support of the gradually merging northeast Pacific and north Canada upper vortices). I have peak odds of tropical cyclone formation set slightly above the NHC 8 AM EDT outlook... at 30%... as the majority of global models this morning (GFS... NAVGEM... and ECMWF) favor tropical cyclone formation. The thermodynamic picture becomes less favorable for tropical cyclone formation by 96 hours when this system moves northeast into waters below 26 deg C... and while this system ingests cooler drier air behind the cold front it will be merging with during that time.
Noting in the long range (beyond day 5) the remnants of this system... if it retains its identity along the cold front... could become entangled with an upper vortex that breaks off from the south side of the front's upper trough. The seperation of the upper vortex and subsequent possible south drift of the upper vortex into 26+ deg C waters between Bermuda and the northern Caribbean Islands would be due to the force of Gulf of Mexico upper ridging which is forecast to expand in the 5 to 7 day window (see intro section of this update for more info on the Gulf of Mexico forecast). Therefore its possible this area of interest makes a comeback as a tropical or subtropical disturbance between Bermuda and the northern Caribbean Islands... supported by the divergence zone of the cut-off upper vortex... in the long range.
Even though tropical cyclone formation is not expected in the short-term... expect heavy rainfall with flash flooding potential across the central and southern parts of the Florida peninsula... as well as the northwestern Bahamas... over the next 36 hours.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Jun 12)... 0% chance of tropical cyclone formation (offshore of northeastern Florida near 29.5N-80W)
IOH 48 Hr Outlook (1200Z Jun 13)... 10% chance of tropical cyclone formation (offshore of northeastern Florida near 29.5N-78.5W)
IOH 72 Hr Outlook (1200Z Jun 14)... 30% chance of tropical cyclone formation (offshore of the southeastern United States near 30N-77W)
IOH 96 Hr Outlook (1200Z Jun 15)... 0% chance of tropical cyclone formation (midway between Carolinas and Bermuda near 32N-72W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 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 (Jun 11) CMC Model Run...
**For area of interest #4... crosses over northern Florida and reaches 30.5N-80W through 42 hours without developing a fully-closed surface circulation... becomes a weak surface low that accelerates northeast parallel to the United States east coast through 96 hours while embedded in flow ahead of approaching surface cold front (surface low located at 34.5N-71.5W at 96 hours)... through 144 hours transitions into elongated non-tropical frontal low that passes just southeast of Newfoundland.
**Surface trough currently over the Yucatan peninsula drifts west into the Bay of Campeche through 120 hours... northern part of the surface trough develops into a tropical low offshore of Louisiana at 144 hours which soon curves north and makes landfall through 156 hours.
**Southeastern Caribbean tropical wave currently at 62W longitude evolves into western Caribbean tropical low just offshore of Belize at 150 hours... subsequently the tropical low curves northwest across the Yucatan peninsula and enters the southwestern Gulf of Mexico through 168 hours (tropical cyclone formation suggested shortly afterwards)
0000Z (Jun 11) ECMWF Model Run...
**For area of interest #4... crosses over northern Florida over next 24 hours and develops into a small and weak surface low near 30N-80W by 36 hours... potentially becomes a tropical depression offshore of the Carolinas and near 31.5N-77.5W at 54 hours... subsequently becomes absorbed by approaching surface cold front from the northwest through 102 hours.
**Surface trough currently over the Yucatan peninsula drifts west across Bay of Campeche and southwestern Gulf of Mexico through 168 hours without further development
0600Z (Jun 11) GFS Model Run...
**For area of interest #4... crosses over northern Florida and reaches 31N-79W through 42 hours without developing a fully-closed surface circulation... develops a weak but closed surface circulation near 31N-75W at 72 hours and potentially becomes a tropical depression near 31.5N-75W through 84 hours... subsequenlty merges with cold front incoming from the northwest through 111 hours and is kicked east... remnant weak frontal low passes just north of Bermuda at 123 hours and gradually loses its identity as the front continues east into the open central Atlantic.
**Surface trough currently over the Yucatan peninsula drifts west across the western Gulf of Mexico and Bay of Campeche through 129 hours... north part of surface trough becomes a tropical low offshore of Louisiana at 132 hours which soon curves north and northwest and makes landfall over southwestern Louisiana at 147 hours.
**Southeastern Caribbean tropical wave currently at 62W longitude evolves into western Caribbean tropical low just offshore of Belize at 144 hours... subsequently the tropical low merges with remnant southern portion of western Gulf/Bay of Campeche surface trough to produce a broad tropical low with two centers (one offshore of Belize and one in the western Bay of Campeche) through 168 hours.
0600Z (Jun 11) NAVGEM Model Run...
**For area of interest #4... crosses over northern Florida over next 18 hours while developing a closed surface circulation... while continuing northeast develops into a weak tropical cyclone near 30.5N-79.5W at 30 hours... while merging with incoming cold front from the west transitions into an elongated non-tropical frontal low while offshore of the Carolinas through 90 hours and loses identity along the front shortly thereafter.
**Surface trough currently over the Yucatan peninsula drifts west across Bay of Campeche and southwestern Gulf of Mexico through 168 hours without further development
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