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Potential Tropical Cyclone Eighteen Forecast Discussion Number 1
2017-10-27 22:45:23| National Hurricane Center (Atlantic)
Issued at 500 PM EDT Fri Oct 27 2017 000 WTNT43 KNHC 272045 TCDAT3 Potential Tropical Cyclone Eighteen Discussion Number 1 NWS National Hurricane Center Miami FL AL182017 500 PM EDT Fri Oct 27 2017 Data from an Air Force Reserve Hurricane Hunter aircraft investigating the disturbance over the northwestern Caribbean Sea indicate that the system does not yet have a well-defined center. In fact, the aircraft data and satellite imagery suggest that there are multiple circulations embedded within a broader circulation at this time. Given the lack of a well-defined center, the system is not a tropical cyclone, but since tropical storm conditions are expected to affect Cuba and the northwestern Bahamas in the next 24 to 36 hours, advisories are being initiated on the system as a potential tropical cyclone at this time. The initial intensity is set to 35 kt based on aircraft data, with these winds found well south of the broad circulation center. However, NOAA buoy 42057 also reported a peak 1-minute wind of 31 kt earlier today. Aircraft data suggest that the central pressure is around 1006 mb. The system is situated in a low-shear environment and over warm waters, so some slow strengthening is expected in the first 24 hours before the system reaches Cuba. The official forecast follows the trend of the intensity consensus in showing a peak of around 45 kt at 36 and 48 hours before the system is absorbed by an approaching cold front in 60-72 hours. Given the lack of a well-defined center, the initial position is and the initial motion of 330/05 are highly uncertain. A faster northward motion should begin soon as the disturbance begins to recurve ahead of an approaching mid/upper-level trough moving into the southeastern United States. This trough should cause a faster northeastward acceleration at 24 through 48 hours. The track model guidance is in generally good agreement on the overall scenario, with more along than cross track spread. The NHC forecast leans toward a blend of the ECMWF and GFS models and is a little slower than the current multi-model consensus. Not surprisingly, given the disorganized initial state of the system, the track forecast uncertainty is larger than usual. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 17.5N 84.5W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 12H 28/0600Z 19.1N 84.1W 35 KT 40 MPH...TROPICAL STORM 24H 28/1800Z 21.7N 82.4W 40 KT 45 MPH 36H 29/0600Z 24.6N 79.6W 45 KT 50 MPH 48H 29/1800Z 28.0N 75.5W 45 KT 50 MPH 72H 30/1800Z...ABSORBED $$ Forecaster Brennan
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