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| #1016209 (Received by flhurricane at: 4:56 AM 12.Sep.2020) TCDAT2 Tropical Storm Paulette Discussion Number 22 NWS National Hurricane Center Miami FL AL172020 500 AM AST Sat Sep 12 2020 Conventional satellite imagery shows that the cyclone`s cloud pattern has improved during the past several hours and that Paulette maybe on the cusp of becoming a hurricane very soon. An Advanced Technology Microwave Sounder (ATMS) overpass suggested that the cyclone has a much less vertical tilt and deep convective banding is developing in the south and east portions of Paulette. The subjective and objective satellite intensity T-numbers haven`t changed from 6 hours ago, and the initial intensity is held at 60 kt. The UW-CIMSS shear analysis reveals some decrease in the shear magnitude and the upper wind pattern has become much more diffluent. The ECMWF/FV3 SHIPS and the large-scale models indicate that the shear will relax soon, and Paulette should become a hurricane today and further strengthen to a major hurricane early Tuesday. The SHIPS statistical-dynamical model indicates this scenario occuring earlier, Monday evening. The official intensity forecast is nudged slightly higher than the previous one and is close to the the HFIP Corrected Consensus Approach intensity model. It is also important to note that the average NHC intensity errors are around 10-15 kt at 48-72 h, the range at which Paulette will likely be nearest to Bermuda. The initial motion is estimated to be northwestward, or 310/15 kt. A mid-tropospheric ridge/Bermuda high north of the cyclone should continue to build across the western Atlantic and steer Paulette west-northwestward for the next 36 hours. Afterward, a turn toward the northwest to north-northwest with a significant increase in forward speed is expected early Monday and Monday evening in response to an approaching mid-latitude major shortwave trough. The track guidance suite remains tightly clustered with just some minor forward speed differences beyond day 3, so it`s quite certain that Paulette will move near Bermuda early Monday, though it`s a little too early to specify the exact closest approach. The NHC track forecast is close to the previous advisory and once again is based on the various multi-model guidance. Key Messages: 1. Paulette is expected to approach Bermuda as a hurricane on Sunday and Monday. A prolonged period of strong winds, storm surge, and heavy rainfall on Bermuda beginning Sunday night is becoming increasingly likely. A tropical storm warning and a hurricane watch have been issued for the island. 2. Swells produced by Paulette are affecting portions of the Leeward Islands and will continue to spread westward to the Greater Antilles, the Bahamas, Bermuda, and the southeastern United States through the weekend. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 26.8N 56.1W 60 KT 70 MPH 12H 12/1800Z 28.0N 58.0W 70 KT 80 MPH 24H 13/0600Z 29.2N 60.5W 75 KT 85 MPH 36H 13/1800Z 30.3N 62.9W 80 KT 90 MPH 48H 14/0600Z 31.8N 64.8W 85 KT 100 MPH 60H 14/1800Z 33.5N 65.2W 90 KT 105 MPH 72H 15/0600Z 35.2N 63.2W 95 KT 110 MPH 96H 16/0600Z 38.2N 56.9W 95 KT 110 MPH 120H 17/0600Z 41.5N 49.7W 80 KT 90 MPH $$ Forecaster Roberts |
