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#798224 (Received by flhurricane at: 4:47 PM 25.Aug.2015) TCDAT5 TROPICAL STORM ERIKA DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052015 500 PM AST TUE AUG 25 2015 After becoming quite disorganized in appearance earlier today, Erika has made a bit of a comeback with increased deep convection near and to the south of the center. Data from the Air Force Hurricane Hunters indicate that the intensity is near 35 kt and this is consistent with Dvorak estimates from both TAFB and SAB. Erika has limited upper-level outflow over the northern semicircle of the circulation, and microwave data suggest that the cyclone has been ingesting some dry mid-level air. As in the previous forecast, there is considerable uncertainty as to the future intensity of this tropical cyclone. The SHIPS guidance indicates increasing west-northwesterly shear over the next few days, and the GFS and ECMWF global models do not strengthen the system during the forecast period. The HWRF and GFDL models do show strengthening, however, but along a track to the right of most of the guidance. The official intensity forecast has been reduced a bit from the previous one and is close to the model consensus. A center fix from the aircraft indicates that the motion continues to be near 280/17. A mid-level subtropical ridge to the north of Erika should steer the system on a west-northwestward track for the next several days. Late in the forecast period, there is significant spread in the models, with those models that depict a weaker system being farther south and west and those having a stronger cyclone farther to the north and east. The official track forecast has been adjusted a little to the left of the previous one and is in line with the latest dynamical model consensus. Some of the tropical storm watches for the islands of the northeastern Caribbean may need to be changed to warnings on the next advisory package. FORECAST POSITIONS AND MAX WINDS INIT 25/2100Z 15.6N 52.8W 35 KT 40 MPH 12H 26/0600Z 16.1N 55.1W 35 KT 40 MPH 24H 26/1800Z 16.7N 58.4W 40 KT 45 MPH 36H 27/0600Z 17.4N 61.4W 45 KT 50 MPH 48H 27/1800Z 18.2N 64.3W 50 KT 60 MPH 72H 28/1800Z 20.3N 69.7W 50 KT 60 MPH 96H 29/1800Z 22.5N 74.0W 55 KT 65 MPH 120H 30/1800Z 25.0N 78.0W 65 KT 75 MPH $$ Forecaster Pasch |