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Tropical Storm Paulette Forecast Discussion Number 16
2020-09-10 22:34:21| National Hurricane Center (Atlantic)
Issued at 500 PM AST Thu Sep 10 2020 000 WTNT42 KNHC 102034 TCDAT2 Tropical Storm Paulette Discussion Number 16 NWS National Hurricane Center Miami FL AL172020 500 PM AST Thu Sep 10 2020 Continuous bursts of deep convection have been ongoing to the north and northeast of Paulette's center of circulation, with the cyclone being affected by nearly 40 kt of deep-layer southwesterly shear. The highest intensity estimates are Dvorak classifications of T3.0/45 kt from TAFB and SAB, and that value remains the initial intensity. The shear should reach its peak magnitude this evening, which is likely to cause Paulette to weaken slightly during the next 24 hours. However, gradual re-strengthening is forecast to begin in about 36 hours, and the rate of intensification is expected to increase in 2 to 3 days when the shear could fall to 10 kt or less, along with a more unstable atmosphere and warmer sea surface temperatures. Paulette is now forecast to become a hurricane by day 3 and continue to intensify through the end of the forecast period. As was advertised in the previous forecast package, the new NHC forecast intensities have been bumped up on days 3 through 5 and now lie near or just below the IVCN intensity consensus and the HCCA corrected consensus aid. Paulette's heading over the past 6-12 hours has been toward the west-northwest, or 300/8 kt. The cyclone's trajectory is expected to oscillate between northwest and west-northwest for the next 4 days, being dictated by the strength of the subtropical ridge to the north and the depth of the steering flow depending on Paulette's intensity. The updated NHC track forecast during this period has been nudged a bit to the north, mostly to account for an adjustment of the initial position. The model guidance all agree that Paulette should turn northward around the western side of a central Atlantic high pressure area by day 5, with the expected hurricane likely to make a tight recurvature near Bermuda. There remains some uncertainty on exactly where that turn will occur, but for now the NHC forecast lies between the tighter-turning ECMWF and HCCA models and the more gradually-turning GFS and HWRF models. Key Messages: 1. Paulette is expected to approach Bermuda as a hurricane this weekend and make its closest approach to the island on Monday and Tuesday. While the exact details of Paulette's track and intensity near the island are not yet known, the risk of strong winds, storm surge, and heavy rainfall on Bermuda continues to increase. 2. Swells produced by Paulette are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, and the southeastern United States into the weekend. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 10/2100Z 22.1N 50.1W 45 KT 50 MPH 12H 11/0600Z 22.5N 51.5W 40 KT 45 MPH 24H 11/1800Z 23.6N 53.4W 40 KT 45 MPH 36H 12/0600Z 25.0N 55.1W 45 KT 50 MPH 48H 12/1800Z 26.6N 56.8W 45 KT 50 MPH 60H 13/0600Z 28.0N 58.9W 55 KT 65 MPH 72H 13/1800Z 29.2N 61.4W 65 KT 75 MPH 96H 14/1800Z 31.5N 65.5W 75 KT 85 MPH 120H 15/1800Z 34.5N 64.0W 80 KT 90 MPH $$ Forecaster Berg
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