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#898278 (Received by flhurricane at: 10:50 AM 13.Aug.2017) TCDAT3 Tropical Depression Eight Discussion Number 3 NWS National Hurricane Center Miami FL AL082017 1100 AM EDT Sun Aug 13 2017 The overall organization of the depression has changed little this morning. Visible satellite imagery and NOAA buoy data indicate that center is located near the northwestern edge of the area of convective banding. In fact, nearly all of the convective banding is located over the eastern and southeastern portions of the circulation. The initial intensity remains 30 kt, which is supported by subjective Dvorak T-numbers of 2.0 from both TAFB and SAB. The depression is moving north-northwestward or 335/11 kt. The track forecast reasoning remains unchanged. The depression is forecast to move north-northwestward to northward around the western portion of a deep-layer subtropical ridge during the next day or so. After that time, the cyclone is expected to turn northeastward ahead of a shortwave trough that will be approaching the northeastern United States. As the southwesterly flow increases over the western Atlantic ahead of the trough by 72 hours, the cyclone should begin to accelerate northeastward. The track guidance is once again in excellent agreement, and only a slight westward adjustment from the previous forecast was required. The depression is currently over warm water and within a low shear environment, but the mid-level atmosphere is relatively dry. These conditions should allow some modest strengthening during the next day or so. Vertical shear is forecast to increase by late Monday, and increase further in 2 to 3 days, which should put an end to any additional intensification. The system is forecast to become extratropical in 3 to 4 days, but if it does not strengthen it could be absorbed by an approaching trough off the Mid-Atlantic and northeastern U.S. in a few days. The latter portion of the forecast continues to be based on guidance provided by the NOAA Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 27.4N 71.5W 30 KT 35 MPH 12H 14/0000Z 29.1N 72.2W 35 KT 40 MPH 24H 14/1200Z 30.7N 72.4W 40 KT 45 MPH 36H 15/0000Z 32.5N 71.9W 45 KT 50 MPH 48H 15/1200Z 34.6N 70.5W 50 KT 60 MPH 72H 16/1200Z 39.0N 62.0W 50 KT 60 MPH 96H 17/1200Z 42.5N 49.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 18/1200Z 47.0N 35.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown |