*******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 AUGUST 1 2024 12:10 PM EDT...
The following is the birdseye view chart effective yesterday evening which was intended to be released with this update. Now that power is restored at my residence I was able to finish yesterday evening's chart and post it here:
...WEDNESDAY JULY 31 2024 11:35 PM EDT...
Note this update has been released using cellular data and without the usual birdseye chart (showing recent birdseye view satellite image of the Atlantic… surface map… and upper air map) due to a recent power outage at my residence… and without power I do not have access to the tools to complete the birdseye view chart. When power is restored I will add the chart later.
For the mid-latitudes of the Atlantic basin... upper vorticity that was parked near the northeastern United States/Canada border has moved into offshore waters from the Carolina coast to the Atlantic Canada coast. Divergence between northwesterlies flowing into the back side of the offshore upper vorticity and southwesterlies associated with the upper trough now approaching from eastern Canada appear to have generated a mid-level spin offshore of the Carolinas in satellite pictures and animation... and confirmable by the CIMSS 850 mb vorticity product (https://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor&zoom=&time=). This low pressure spin is slated to accelerate northeastward over the next couple of days parallel to the northeastern US and Atlantic Canada shoreline... in the flow ahead of the aforementioned eastern Canada upper trough and surface frontal system. The divergence ahead of the approaching upper trough may be a boon for possible tropical development of this low pressure spin... especially if it can accelerate northeastward fast enough to mitigate the effect shearing upper southwesterlies ahead of the upper trough... before the spin merges with the incoming surface front and moves into cooler waters. Will upgrade this spin to an area of interest for possible tropical development in future updates if necessary.
In the tropical latitudes of the Atlantic basin... the northwest end of a tropical wave of low pressure has seen a notable increase in thunderstorms while overspreading the northeastern Caribbean Islands. Interests across western Cuba and the Florida peninsula need to monitor the progress of the wave for possible late weekend or Monday tropical cyclone formation as the forecast upper wind profile over this system becomes increasingly conducive for development around that timeframe. See area of interest #14 section below for more information.
AREA OF INTEREST #14... The large surface tropical wave of low pressure that has been approaching the eastern Caribbean Islands over the past couple of days has been suppressed by a combination of dry Saharan air and overhead upper vorticity. As seen on visible satellite pictures and 0600Z NHC TAFB surface analysis from early Wednesday... the wave has taken on a northwest-southeast tilt which is likely due to the wave being a merger of multiple surface features one of which was a low-latitude pre-existing spin that has been near 50W longitude. It is probable the the main area of spin associated with the wave was flung westward into the northeastern Caribbean Islands in a fujiwhara-type interaction with the pre-existing spin near 50W... and the two features taken together effectively make the northwest-southeast tilted tropical wave axis. The northwestern part of the wave has seen a notable increase in thunderstorms that have spread across the northeastern Caribbean Islands (northern Lesser Antilles... Virgin Islands... and Puerto Rico) while interacting with the eastern divergence zone of an upper vortex near Hispaniola (Haiti and the Dominican Republic). This is now the most likely portion of the wave to develop and the updated forecast track in the outlook below has been adjusted accordingly... and for the next 24 hours this portion of the wave is likely to remain active while nearing the Dominican Republic while continuing to interact with the Hispaniola upper vortex. Between 24 and 48 hours the upper vortex currently near the Lesser Antilles merges with the upper vortex near Hispaniola into a NW/SE tilted inverted upper trough which begins to retrograde toward Central America while pushed by the southern US upper ridge... and the surface tropical wave around 48 hours may become suppressed by convergence on the east side of the inverted upper trough as the surface wave shifts across the southeastern half of the Bahamas and eastern Cuba. By 72 hours the inverted upper trough toward Central America begins to weaken from prolonged isolation from high-latitude cold air... resulting in an expanding upper anticyclone between the weakening inverted upper trough and western Atlantic cut-off upper vortex currently near 25N-60W favoring the surface wave with low shear and upper outflow as it moves toward western Cuba and the southern Florida peninsula... this is when I raise odds of tropical cyclone formation above 0%. To close out the 5-day forecast period... a northward turn across the Florida peninsula and into the waters just offshore of the southeastern United States is shown due to the surface ridge weakness of a large eastern North America frontal system to be supported by the upper trough currently moving into central North America. Despite land interaction with the Florida peninsula... odds of tropical cyclone formation remain above 0% during this timeframe as the center of whatever circulation develops may be close enough to the rather warm 30+ deg C water surrounding the peninsula to still become a tropical cyclone even if the center is located just inland... however I cap the odds at 30% as an acknowledgement of the land interaction plus the potential for northerly shear around day 5 from a southward-sagging band of upper vorticity that the models insist will be left behind by the upper trough associated with the eastern North America frontal system. Noting my 30% peak odds are higher than yesterday as the tropical wave has already seen an increase in thunderstorms and the future upper air pattern that will support more thunderstorms and possible tropical cyclone formation (discussed above) is becoming clearer.
The longer range fate of this area of interest... beyond day 5... has uncertainty as is usual with long range forecasts... but two scenarios are presenting themselves in the suite of global models. The CMC and ECMWF which are quicker with the northward turn have the upper trough associated with the eastern North America frontal system accelerate this system northeastward parallel to the United States east coast... and even suggest wind shear associated with the upper trough may be lessened by the northeastward speed which would be parallel to the shearing upper wind vectors such that the divergence zone of the upper trough may end up aiding this system's tropical development. The GFS which is slower with the northward turn has this system miss the exit with the surface ridge weakness and upper trough... leaving this system to meander for a few days in the vicinity of the Florida peninsula while jammed in between the Atlantic surface ridge and surface ridge building behind the exiting surface frontal system. Will see which scenario becomes more likely in future updates... lets hope that we do not end up with a meandering system near land areas that would create prolonged hazards such as severe flooding from prolonged heavy rainfall.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Aug 1)... 0% chance of tropical cyclone formation (north coast of the Dominican Republic near 19.5N-70W)
IOH 48 Hr Outlook (1800Z Aug 2)... 0% chance of tropical cyclone formation (north coast of eastern Cuba near 21.2N-76W)
IOH 72 Hr Outlook (1800Z Aug 3)... 15% chance of tropical cyclone formation (north coast of Cuba near 23N-80W)
IOH 96 Hr Outlook (1800Z Aug 4)... 30% chance of tropical cyclone formation (southwestern Florida peninsula but near the coast in vicinity of 26.5N-81W)
IOH 120 Hr Outlook (1800Z Aug 5)... 30% chance of tropical cyclone formation (just offshore of northeastern Florida near 30N-80.5W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 8 PM EDT**************************
Formation chance through 48 hours... 0%
Formation chance through 7 days... 60%
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/).
0000Z (Jul 31) CMC Model Run...
**For area of interest #14... evolves into a broad tropical low in the vicinity of western Cuba and the Cayman Islands at 78 hours which then curves north across the eastern Gulf of Mexico and northern Florida through 120 hours... offshore portion of circulation develops a better-defined center near South Carolina coast at 132 hours which becomes a tropical cyclone just offshore of southeastern North Carolina at 144 hours... tropical cyclone centered just east-southeast of Cape Hatteras North Carolina by 168 hours
**Offshore Mid-level circulation currently position just southeast of the North Carolina/South Carolina border evolves into a surface low near 38.5N-69W at 48 hours... while paralleing Atlantic Canada coast while on an east-northeast trajectory gradually merges with cold front pushed offshore by current east Canada frontal low through 78 hours... while curving east in open north-central Atlantic the remnant frontal low loses identity along the front by 102 hours.
0000Z (Jul 31) ECMWF Model Run...
**For area of interest #14... north side of tropical wave turns north in flow ahead of incoming eastern North America frontal system and evolves into a tropical low just offshore of east-central Florida by 108 hours... subsequently curves north-northeast in track with tropical cyclone formation offhsore of the Carolinas and near 31.5N-77.5W at 126 hours... intensifies into a hurricane near 36.5N-69.5W through 168 hours
1200Z (Jul 31) GFS Model Run...
**For area of interest #14... north side of tropical wave fractures into a surface trough that turns north into the eastern Gulf of Mexico waters offshore of the southwest Florida peninsula coast through 90 hours... while continuing to drift north the surface trough intensifies into a small tropical cyclone just offshore of the northwest Florida peninsula coast by 111 hours... the small tropical cyclone becomes quasi-stationary over the eastern Florida panhandle but close to water through 132 hours while trapped between the Atlatnic surface ridge to the east and eastern North America surface ridge building behind a departing lengthy front to the north... southward-sagging upper vorticity left behind the front's upper trough tries to drag the tropical cyclone slowly southeastward along the northwestern Florida peninsula coast through 168 hours.
0600Z (Jul 31) NAVGEM Model Run...
**For area of interest #14... no development shown
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