Official Discussion issued by the National Hurricane Center
Twelve (AL122024) DATA RELEASED: 9/29/2024 9:00:00 PM UTC
Copy of official data Tropical Depression Twelve Discussion Number 1 NWS National Hurricane Center Miami FL AL122024 500 PM AST Sun Sep 29 2024 The system we have been monitoring in the eastern Tropical Atlantic (AL90) has continued to become better organized throughout the day. After an overnight deep convective burst, outer convective banding has become better defined, noted by the most recent TAFB subjective Dvorak fix of T2.0/30 kt. GOES-16 1-minute visible imagery also shows that the circulation, which was more elongated this morning, has become better defined on the western side, suggesting a well-defined closed vortex now exists. Based on the above data, advisories are initiated on Tropical Depression Twelve this afternoon, with an initial intensity of 30 kt. The motion of the new depression currently appears to be westward at 270/8 kt. A prominent subtropical ridge to the north should continue to steer the system generally westward to west-northwestward over the next couple of days. After that time, this ridge becomes more eroded by a mid-latitude trough on its western side, resulting in the system gradually turning more poleward through the end of the forecast. In general the guidance is pretty tightly clustered for the first 48-60 h, with spread increasing a little more thereafter related to how quickly the system turns poleward. The initial NHC track forecast lies near the HFIP Corrected Consensus Approach (HCCA), which favors the ECMWF track a little further west than the GFS track. For at least the next 2-3 days, vertical wind shear is expected to remain low, mid-level moisture stays high, as the system remains over 29-30 C sea-surface temperatures. Yet, the current large convective envelope of the system suggests it may take a day or so for an inner-core to become established. Thus, the initial rate of intensification is a bit slow, a little under the guidance for the next 24 hours, but then becomes faster and ends up near the IVCN consensus aid by 120 h. The initial NHC intensity forecast shows TD12 becoming a hurricane in 60 h and a major hurricane in 5 days. FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 13.8N 32.5W 30 KT 35 MPH 12H 30/0600Z 13.9N 33.6W 35 KT 40 MPH 24H 30/1800Z 14.2N 35.7W 40 KT 45 MPH 36H 01/0600Z 14.5N 38.1W 50 KT 60 MPH 48H 01/1800Z 15.0N 40.0W 60 KT 70 MPH 60H 02/0600Z 15.9N 41.5W 70 KT 80 MPH 72H 02/1800Z 17.4N 42.7W 85 KT 100 MPH 96H 03/1800Z 20.0N 45.0W 95 KT 110 MPH 120H 04/1800Z 22.5N 47.5W 105 KT 120 MPH $$ Forecaster Papin |