ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM Tropical Storm Iselle Discussion Number 12 NWS National Hurricane Center Miami FL EP142020 200 AM PDT Sat Aug 29 2020 Iselle has become less organized during the past several hours. The low-level center is exposed to the east of a decaying and disheveled area of deep convection. An ASCAT-B overpass from around 0430 UTC showed maximum winds in the 40-45 kt range, but since the system's appearance has degraded since that time, the initial intensity is set at 40 kt. This value is also in agreement with an average of the latest satellite intensity estimates, which range from 33 to 45 kt. Iselle is feeling the effects of about 25 kt of easterly vertical wind shear. Since the shear is expected to remain strong while Iselle heads for cooler waters and a drier air mass, steady weakening is anticipated. Iselle will likely become a tropical depression by tonight and a remnant low on Sunday. Most of the models show the remnant low dissipating in 3 days, and so does the official forecast. The compact tropical storm is moving northward at about 5 kt. A continued northward motion is expected for another day or so, followed by a turn to the northwest when Iselle becomes a weak and shallow system and moves in the low-level flow. The new NHC track forecast is a little to the east of the previous one to come into better agreement with the latest consensus aids. The initial 34-kt wind radii have been modified slightly based on the aforementioned ASCAT data. FORECAST POSITIONS AND MAX WINDS INIT 29/0900Z 19.7N 115.1W 40 KT 45 MPH 12H 29/1800Z 20.7N 114.9W 35 KT 40 MPH 24H 30/0600Z 22.2N 114.9W 30 KT 35 MPH 36H 30/1800Z 23.5N 115.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 31/0600Z 24.5N 115.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 60H 31/1800Z 25.3N 116.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 01/0600Z...DISSIPATED $$ Forecaster Cangialosi NNNN
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Page last modified: Thursday, 31-Dec-2020 12:11:30 UTC