Issued at 1100 PM EDT Fri Sep 26 2025
000 WTNT44 KNHC 270237 TCDAT4 Potential Tropical Cyclone Nine Discussion Number 2 NWS National Hurricane Center Miami FL AL092025 1100 PM EDT Fri Sep 26 2025 Many thanks to the crew of a NOAA P-3 Hurricane Hunter aircraft, which has been flying a surveillance mission in the disturbance this evening. Dropsonde data from this flight, as well as surface observations from Cuba, suggest that the system is still a trough of low pressure, and the trough axis is a little farther west than previously estimated. Maximum winds remain near 30 kt, and the pressure has dropped slightly to 1007 mb based on the dropsonde data. The current motion is now estimated to be northwestward, or 305/8 kt. The system is expected to slow down and turn north-northwestward by Saturday morning and continue that trajectory over the weekend, embedded in the southerly flow between a deep-layer trough over the southeastern U.S. and a ridge over the west-central Atlantic. The track models are in good agreement for the first 3 days of the forecast. The new NHC forecast track has been shifted westward during that period, mainly due to the westward adjustment of the initial position, but it is also a bit slower than the previous prediction based on the latest guidance. There is significantly more uncertainty in the track forecast after day 3, but at the very least it appears that the system will slow down considerably and perhaps even stall near the coast of South Carolina. Interestingly, the 18z GFS and ECMWF solutions no longer show the system moving inland over the southeastern U.S. and have come more in line with their respective ensemble means, as well as the HCCA consensus aid and Google DeepMind mean. For this new forecast, a very slow, nearly stationary motion is shown on day 5, with perhaps some hint of the start of a northeastward motion. That said, even if the system stalls just offshore, it would still be large enough to cause wind and coastal flooding impacts along the southeastern U.S. coast, as well as heavy rainfall/flooding concerns in inland areas. Global models suggest it will still take another 24 hours or so for the system to develop a well-defined circulation and organized convection to be classified as a tropical depression. After that time, strengthening is expected while the system moves over very warm waters and within a divergent upper-level environment. The NHC forecast continues to show the system reaching hurricane strength in 3-4 days, which is close to the HCCA and IVCN consensus aids. Stronger shear, and possibly the beginnings of an interaction with a nearby frontal boundary, could cause some weakening by day 5. KEY MESSAGES: 1. The disturbance is forecast to become a tropical storm this weekend and bring tropical storm conditions to portions of the central and northwestern Bahamas, where Tropical Storm Warnings and Watches, respectively, are in effect. Rainfall associated with this system will impact eastern Cuba, Hispaniola, Jamaica, and the Bahamas through the weekend. 2. There is an increasing threat of heavy rainfall early next week from coastal Georgia through the Carolinas and into the southern Mid-Atlantic states, which could cause flash, urban, and river flooding. 3. The system is expected to be at or near hurricane intensity when it approaches the southeast U.S. coast early next week, where there is a risk of storm surge and wind impacts. Residents in that area should monitor updates to the forecast and ensure they have their hurricane plan in place. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 21.5N 76.0W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 12H 27/1200Z 22.2N 76.6W 30 KT 35 MPH...POTENTIAL TROP CYCLONE 24H 28/0000Z 23.3N 77.0W 30 KT 35 MPH...TROPICAL CYCLONE 36H 28/1200Z 24.8N 77.5W 35 KT 40 MPH 48H 29/0000Z 26.3N 77.9W 45 KT 50 MPH 60H 29/1200Z 28.2N 78.3W 55 KT 65 MPH 72H 30/0000Z 30.1N 78.9W 65 KT 75 MPH 96H 01/0000Z 32.0N 79.2W 65 KT 75 MPH 120H 02/0000Z 32.4N 78.7W 55 KT 65 MPH $$ Forecaster Berg
