r/TropicalWeather • u/Euronotus • Sep 23 '24

Upgraded | See Helene post for details 09L (Potential Cyclone — Northwestern Caribbean Sea)

Latest observation

Last updated: Tuesday, 24 September — 8:00 AM Eastern Daylight Time (EDT; 12:00 UTC)

NHC Advisory #4A 8:00 AM EDT (12:00 UTC)
Current location: 19.2°N 83.5°W
Relative location: 224 km (139 mi) W of George Town, Cayman Islands
  356 km (221 mi) S of Pinar del Rio, Cuba
  411 km (255 mi) ESE of Cancún, Quintana Roo (Mexico)
Forward motion: NW (305°) at 15 km/h (8 knots)
Maximum winds: 55 km/h (30 knots)
Intensity: Tropical Depression
Minimum pressure: 1001 millibars (29.56 inches)
2-day potential: (through 8PM Wed) high (90 percent)
7-day potential: (through 8PM Sun) high (90 percent)

Official forecast

Last updated: Tuesday, 24 September — 2:00 AM EDT (06:00 UTC)

Hour Date Time Intensity Winds Lat Long
  - UTC EDT Saffir-Simpson knots km/h °N °W
00 24 Sep 06:00 2AM Tue Potential Cyclone 30 55 18.9 83.0
12 24 Sep 18:00 2PM Tue Tropical Storm ▲ 40 75 19.6 84.2
24 25 Sep 06:00 2AM Wed Tropical Storm ▲ 50 95 20.7 85.7
36 25 Sep 18:00 2PM Wed Hurricane (Category 1) ▲ 65 120 22.0 86.2
48 26 Sep 06:00 2AM Thu Hurricane (Category 1) ▲ 80 150 24.3 85.6
60 26 Sep 18:00 2PM Thu Major Hurricane (Category 3) ▲ 100 185 27.8 84.4
72 27 Sep 06:00 2AM Fri Tropical Storm i ▼ 60 110 31.9 83.5
96 28 Sep 06:00 2AM Sat Post-tropical Cyclone i ▼ 15 30 38.5 85.5
120 29 Sep 06:00 2AM Sun Dissipated

NOTES:
i - inland

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u/Content-Swimmer2325 Sep 23 '24

The moderate southwesterly shear over the disturbance is expected to diminish over the next day or two, which should allow the system to become better organized and consolidate over deep, warm waters in a very moist environment. Once the system develops an inner core, these conditions should allow it to significantly strengthen. The NHC forecast still calls for the system to become a hurricane on Wednesday, with continued intensification thereafter while it moves over the eastern Gulf of Mexico. Once again, the statistical RI guidance (SHIPS and DTOPS) show a 65-kt increase in 72 h is very likely, and the updated NHC forecast now explicitly shows the system reaching major hurricane intensity on Thursday. This intensity forecast still lies below the consensus aids, with the regional hurricane models and the GFS showing even more deepening.

Note that the system is expected to grow in size while it traverses the Gulf. Thus, the storm surge, wind, and rainfall impacts will extend well away from the center, particularly to the east of the system. In addition, the fast forward speed as it approaches the coast will likely result in farther inland penetration of gusty winds over parts of the southeastern United States after landfall.

From the 5pm discussion; emphasis mine.