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| #798297 (Received by flhurricane at: 10:57 PM 25.Aug.2015) TCDAT5 TROPICAL STORM ERIKA DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052015 1100 PM AST TUE AUG 25 2015 Both NOAA and Air Force hurricane hunter planes investigated Erika and found a disorganized storm. The central pressure rose to 1006 mb, and the strongest winds were confined to the eastern semicircle. The low-level center remains exposed to the north of the limited thunderstorm activity. Based on the current appearance on satellite imagery, and data from the plane, the initial intensity is generously kept at 35 kt. The intensity forecast continues to be highly uncertain. Erika has a large cyclonic envelope, and this is a favorable factor for the cyclone to strengthen. However, SHIPS model forecasts a hostile west-northwesterly shear over the cyclone and, in fact, it only strengthens Erika a little bit at the end of the forecast period. This coincides with the solution of the GFS and the ECMWF global models which either weaken the cyclone or show little change in strength. The NHC forecast follows the intensity consensus, and shows a modest strengthening beyond 3 days. By then, the cyclone is expected to be near the Bahamas where the environment could be a little more favorable for intensification. However, I will not be a surprised if Erika dissipates like Danny in the the northeastern Caribbean Sea where the environment is hostile. Erika is embedded within the easterly flow south of a moderate subtropical ridge which is covering the western Atlantic. This pattern will likely continue to steer Erika between the west and west-northwest at about 15 kt for the next 2 to 3 days. As the cyclone reaches the western edge of the ridge in the area of the Bahamas, the cyclone is then expected to decrease in forward speed. The NHC forecast is very similar to the previous one and follows very closely the multi-model consensus. Tropical storm watches and warnings have been adjusted and added for some of the islands of the northeastern Caribbean by the respective Meteorological Services. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 16.0N 54.4W 35 KT 40 MPH 12H 26/1200Z 16.4N 56.9W 35 KT 40 MPH 24H 27/0000Z 17.0N 60.1W 35 KT 40 MPH 36H 27/1200Z 17.8N 63.2W 40 KT 45 MPH 48H 28/0000Z 18.8N 66.0W 40 KT 45 MPH 72H 29/0000Z 21.0N 70.9W 45 KT 50 MPH 96H 30/0000Z 23.0N 75.0W 55 KT 65 MPH 120H 31/0000Z 26.0N 78.5W 65 KT 75 MPH $$ Forecaster Avila |
