Potential Tropical Cyclone Five Discussion Number   4
NWS National Hurricane Center Miami FL       AL052024
1100 AM AST Mon Aug 12 2024

Data from the NOAA Hurricane Hunter aircraft investigating the storm 
indicate a low-level center could be attempting to form closer to 
some increased convective activity within the northern semicircle of 
the disturbance. While the disturbance appears to be gradually 
becoming better organized in satellite imagery, the lack of a 
well-defined center means it will remain a potential tropical 
cyclone for this advisory. Based on the flight-level winds and some 
distant scatterometer data over the eastern part of the circulation, 
the initial intensity is set at 30 kt. An Air Force Reserve 
Hurricane Hunter aircraft will investigate the system this afternoon 
and help us assess any changes to the low-level wind field. 

Overall, the disturbance has moved a little faster to the west than 
previous estimates, and the initial motion remains quickly westward 
(280/23 kt). A westward to west-northwestward motion with some 
decrease in forward speed is expected during the next couple of days 
while the system moves around the southwestern extent of the 
subtropical ridge. This will bring the center over portions of the 
Leeward Islands late tonight into Tuesday, and then near or over the 
Virgin Islands and Puerto Rico late Tuesday night and Wednesday. By 
midweek, the system will reach a weakness in the mid-level ridge 
caused by a mid-latitude trough moving across the western Atlantic. 
This should induce a northwestward to northward motion during the 
latter half of the forecast period. The track guidance envelope has 
shifted to the left of the previous track, likely a product of the 
faster forward speed and the weaker initial state of the system. 
Only small adjustments were made to the near-term NHC track 
forecast, with a slightly larger westward adjustment at days 3-5.

Until the disturbance becomes better organized, the large radius of 
maximum wind and some northeasterly shear should only allow for 
modest strengthening during the next 24-48 h. The NHC forecast shows 
it becoming a tropical storm in 24 h and continuing to slowly 
strengthen while it passes over the northeastern Caribbean Sea. Once 
the system reaches the western Atlantic, the intensity guidance 
favors more significant strengthening, and the system is forecast to 
become a hurricane in 3 days and continue intensifying thereafter. 
No major changes were made to the NHC intensity forecast this cycle, 
which remains close to the multi-model consensus.


Key Messages:

1. The disturbance is expected to become a tropical storm as it 
reaches the Leeward Islands. Tropical Storm Warnings are in effect 
for most of these islands, where tropical storm conditions 
are expected to begin late tonight.

2. Heavy rainfall may result in locally considerable flash flooding 
and mudslides in areas of the Leeward and Virgin Islands by later 
today into Wednesday, and over Puerto Rico late Tuesday into 
Thursday.

3. A Tropical Storm Warning is now in effect for the Virgin Islands 
and Puerto Rico, where tropical storm conditions are expected to 
begin Tuesday night or early Wednesday.


FORECAST POSITIONS AND MAX WINDS

INIT  12/1500Z 15.1N  55.6W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
12H  13/0000Z 15.5N  58.8W   35 KT  40 MPH...POTENTIAL TROP CYCLONE
24H  13/1200Z 16.3N  62.2W   35 KT  40 MPH
36H  14/0000Z 17.3N  64.6W   40 KT  45 MPH
48H  14/1200Z 18.8N  66.4W   45 KT  50 MPH
60H  15/0000Z 20.5N  67.6W   55 KT  65 MPH
72H  15/1200Z 22.7N  68.2W   65 KT  75 MPH
96H  16/1200Z 27.0N  67.5W   85 KT 100 MPH
120H  17/1200Z 31.5N  65.0W   95 KT 110 MPH

$$
Forecaster Reinhart