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#896981 (Received by flhurricane at: 5:57 AM 31.Jul.2017) TCDAT1 Tropical Depression Six Special Discussion Number 1 NWS National Hurricane Center Miami FL AL062017 600 AM EDT Mon Jul 31 2017 Radar imagery from the NWS Tampa Bay WSR-88D indicates that shower and thunderstorm activity associated with the small low pressure area over the eastern Gulf of Mexico have persisted and become better organized overnight. Earlier ASCAT data showed that the system has a well-defined circulation and winds of at least 30 kt over a small area to the north and northwest of the center. Based on these data, advisories are being initiated on a 30-kt tropical depression. The depression is currently embedded within an area of moderate to strong northwesterly shear. Although the upper-level winds could become a little more favorable for strengthening, the depression is expected to move inland over the west-central Florida peninsula later today, and no significant change in wind speed is predicted. After the depression moves over the western Atlantic, increasing westerly shear is forecast to prevent intensification. This scenario is in agreement with the GFS and ECMWF models, which show the system weakening and likely dissipating in 3 to 4 days, or perhaps sooner. The depression is moving eastward at about 7 kt. The cyclone is embedded within the southern portion of a deep-layer trough that extends southwestward along the U.S. east coast. This pattern should steer the system eastward today, then northeastward with some increase in forward speed through dissipation. The track guidance is in relatively good agreement on this scenario, although there are some differences in how fast the system will accelerate northeastward. For now, the NHC forecast lies between the faster HWRF and GFS solutions, and the slower ECMWF. The primary threat with this system is expected to be locally heavy rainfall across portions of the Florida peninsula during the next couple of days. Due to the uncertainty in the intensity forecast, a Tropical Storm Watch has been issued for a portion of the west- central coast of Florida. FORECAST POSITIONS AND MAX WINDS INIT 31/1000Z 27.7N 83.5W 30 KT 35 MPH 12H 31/1800Z 27.7N 82.4W 30 KT 35 MPH 24H 01/0600Z 28.3N 80.6W 30 KT 35 MPH 36H 01/1800Z 29.8N 78.6W 30 KT 35 MPH 48H 02/0600Z 31.6N 76.5W 30 KT 35 MPH 72H 03/0600Z 34.5N 72.0W 30 KT 35 MPH 96H 04/0600Z...DISSIPATED $$ Forecaster Brown |