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#903228 (Received by flhurricane at: 4:37 PM 15.Sep.2017) TCDAT4 Tropical Depression Fourteen Discussion Number 4 NWS National Hurricane Center Miami FL AL142017 500 PM AST Fri Sep 15 2017 The depression has become less organized since earlier today with the center now exposed to the north and northwest of the deep convection due to northwesterly shear. Dvorak data T-numbers have decreased, but an average of the current intensity numbers of 1.5 and 2.5 support maintaining an initial wind speed of 30 kt. Although the depression is forecast to move over warm water, moderate northwesterly shear and dry mid-level air to the north of the cyclone is likely to prevent significant intensification. However, most of the intensity guidance shows some strengthening and the depression is forecast to become a tropical storm within the next day or two. After that time, increasing westerly shear produced by a mid- to upper-level trough over the central Atlantic is expected to weaken the system, and the tropical cyclone is now forecast to degenerate to a remnant low by day 5. The new NHC intensity forecast has been adjusted downward to be in better agreement with the various intensity consensus aids. The depression has jogged a little northward this afternoon, but the long-term motion is west-northwestward at about 10 kt. The depression is expected to move westward to west-northwestward to the south of a narrow ridge over the eastern Atlantic over the weekend. By early next week, the ridge is forecast to weaken as a deep-layer trough becomes established over the east-central Atlantic. This should cause the cyclone to gain some latitude later in the forecast period. The more northward initial position has required a northward adjustment of the track forecast, but the NHC track remains along the southern side of the guidance envelope, in agreement with the typically reliable HFIP corrected consensus model. FORECAST POSITIONS AND MAX WINDS INIT 15/2100Z 12.6N 29.7W 30 KT 35 MPH 12H 16/0600Z 12.8N 30.8W 30 KT 35 MPH 24H 16/1800Z 12.9N 32.2W 35 KT 40 MPH 36H 17/0600Z 13.0N 33.4W 40 KT 45 MPH 48H 17/1800Z 13.2N 34.7W 40 KT 45 MPH 72H 18/1800Z 14.6N 38.4W 35 KT 40 MPH 96H 19/1800Z 16.5N 42.5W 30 KT 35 MPH 120H 20/1800Z 18.5N 46.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown |