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Tropical Storm HARVEY
ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM Tropical Storm Harvey Discussion Number 3 NWS National Hurricane Center Miami FL AL092017 1100 PM AST Thu Aug 17 2017 Since an Air Force Hurricane Hunter aircraft departed the storm a few hours ago, the cloud pattern of Harvey hasn't changed much. Dvorak intensity estimates from both TAFB and SAB are 30 kt, and based on the earlier aircraft measurements the current intensity is held at 35 kt. The storm is in a moderate easterly shear environment, which should allow only slow strengthening for the next couple of days. After that, the dynamical models indicate that a decrease in shear should occur. As noted earlier, however, the GFS and ECMWF global models do not show strengthening of Harvey and in fact practically dissipate it during the forecast period. This suggests something unfavorable in the environment besides shear ahead of the system, perhaps some drier air or subsidence. The official intensity forecast shows modest strengthening and is generally close to the model consensus which includes the statistical/dynamical guidance and the regional hurricane models (that do show some strengthening). The motion continues westward or 270/16. There is no change to the track forecast philosophy from the previous advisory package. Harvey should remain embedded in the flow on the south side of a strong mid-level ridge throughout most of the forecast period, which should steer the system on a continued westward track. Near the end of period, the guidance suggests a slightly more northward motion with some deceleration. The official forecast track is near the dynamical model consensus and very close to the previous NHC track. FORECAST POSITIONS AND MAX WINDS INIT 18/0300Z 13.0N 57.4W 35 KT 40 MPH 12H 18/1200Z 13.2N 59.9W 35 KT 40 MPH 24H 19/0000Z 13.6N 63.3W 40 KT 45 MPH 36H 19/1200Z 13.9N 67.0W 45 KT 50 MPH 48H 20/0000Z 14.1N 70.9W 50 KT 60 MPH 72H 21/0000Z 14.8N 78.6W 60 KT 70 MPH 96H 22/0000Z 16.0N 85.5W 60 KT 70 MPH 120H 23/0000Z 17.5N 89.0W 55 KT 65 MPH...INLAND $$ Forecaster Pasch NNNN