ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM GRACE DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL072015 1100 AM AST MON SEP 07 2015 Grace's cloud pattern has deteriorated somewhat this morning, with the deep convection becoming fragmented and banding features less evident than they were yesterday. The initial intensity is adjusted downward to 40 kt in agreement with data from a recent ASCAT overpass, and in line with the latest subjective Dvorak estimates from SAB and TAFB. An upper-level trough to the northwest of the tropical cyclone is producing some west-southwesterly vertical shear on Grace. The SHIPS model indicates that the shear will increase over the next several days, which should inhibit strengthening. The official intensity forecast calls for little change in strength during the next couple of days followed by gradual weakening. Grace is expected to degenerate into a remnant low by the end of the forecast period. This is similar to the intensity model consensus, IVCN, but given the current state of the system, Grace could weaken faster than indicated here. The storm is moving a little more quickly toward the west this morning, and the motion estimate is 275/15 kt. For the next several days, Grace will continue to be steered by the low- to mid-level flow to the south of the subtropical ridge. The GFS and ECMWF global models show a rather brisk westward motion, perhaps partially because the system opens up into a wave in the model predictions. The official forecast is a bit faster than the previous one and close to the latest model consensus. FORECAST POSITIONS AND MAX WINDS INIT 07/1500Z 13.7N 35.9W 40 KT 45 MPH 12H 08/0000Z 13.9N 38.1W 40 KT 45 MPH 24H 08/1200Z 14.1N 41.5W 40 KT 45 MPH 36H 09/0000Z 14.5N 45.0W 40 KT 45 MPH 48H 09/1200Z 14.9N 48.1W 40 KT 45 MPH 72H 10/1200Z 15.5N 54.5W 35 KT 40 MPH 96H 11/1200Z 16.3N 61.0W 30 KT 35 MPH 120H 12/1200Z 17.0N 66.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Pasch NNNN
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Page last modified: Thursday, 31-Dec-2015 12:09:15 UTC