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Tropical Depression SIX Forecast Discussion Number 1
2014-09-11 16:39:43| National Hurricane Center (Atlantic)
Issued at 1100 AM EDT THU SEP 11 2014 000 WTNT41 KNHC 111439 TCDAT1 TROPICAL DEPRESSION SIX DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062014 1100 AM EDT THU SEP 11 2014 Satellite imagery and a recent ASCAT-B overpass indicate that the low pressure area over the eastern Atlantic has a well-defined circulation and organized convective banding near the center. Thus, advisories are being initiated on Tropical Depression Six. The initial intensity is set at 30 kt based on the scatterometer data and the satellite intensity estimate from TAFB. The initial motion is 310/12. A low-/mid-level ridge north of the cyclone should steer it generally west-northwestward to northwestward for the next 3-4 days. After that, the track guidance forecasts the system to turn generally northward between the ridge and a large mid-/upper-level low south of Bermuda. There is a fair amount of spread in the guidance on where this turn should occur, with the extremes being the Canadian model on the east near 45W and the ECMWF model on the west near 55W. The official forecast lies close to the model consensus in expecting a more northerly motion between 51W-53W. The forecast track keeps the cyclone well away from land for the next 5 days. The depression is currently in an environment of light vertical wind shear. The large-scale models forecast some increase in southerly shear after 24 hours, which should persist through the end of the forecast period. Despite the shear, the intensity guidance forecasts slow but steady strengthening. The official forecast follows this scenario and is a blend of the SHIPS model and the intensity consensus. FORECAST POSITIONS AND MAX WINDS INIT 11/1500Z 16.2N 37.1W 30 KT 35 MPH 12H 12/0000Z 17.1N 38.5W 35 KT 40 MPH 24H 12/1200Z 18.2N 40.7W 40 KT 45 MPH 36H 13/0000Z 19.3N 42.9W 45 KT 50 MPH 48H 13/1200Z 20.5N 44.9W 50 KT 60 MPH 72H 14/1200Z 23.5N 48.5W 55 KT 65 MPH 96H 15/1200Z 26.5N 51.5W 60 KT 70 MPH 120H 16/1200Z 29.0N 53.0W 70 KT 80 MPH $$ Forecaster Beven
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