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Tropical Storm Paulette Forecast Discussion Number 20
2020-09-11 22:50:37| National Hurricane Center (Atlantic)
Issued at 500 PM AST Fri Sep 11 2020 000 WTNT42 KNHC 112050 TCDAT2 Tropical Storm Paulette Discussion Number 20 NWS National Hurricane Center Miami FL AL172020 500 PM AST Fri Sep 11 2020 Paulette inconveniently fell in a gap between all three ASCAT passes this morning, so we haven't gotten any better handle on the cyclone's intensity since last evening's pass. However, Dvorak classifications have not budged, so maintaining the initial intensity of 55 kt seems sound. In addition, although an AMSR microwave pass from around 17 UTC still showed the system being sheared, it also revealed a ragged mid-level eye feature. Since the shear is expected to abate to less than 10 kt by 48 hours, Paulette is likely to intensify, possibly significantly so, and it is now forecast to become a hurricane on Saturday. The intensification trend is expected to continue through day 4, and Paulette has the potential to be a dangerous hurricane when it makes its closest approach to Bermuda on Monday. Paulette's forecast peak intensity (on day 4) has been nudged up slightly, lying near the SHIPS and HCCA guidance, but still a little below the latest HWRF simulation. Paulette has picked up some speed and is now moving toward the northwest (310 degrees) at 11 kt. The track forecast reasoning has not changed since this morning. Paulette should maintain a motion toward the northwest or west-northwest during the next 2 to 3 days to the south of a weakening subtropical ridge. By day 3, a longwave trough is forecast to move across the northeastern United States, eroding the ridge eastward, and causing Paulette to recurve sharply toward the north and northeast in the vicinity of Bermuda on Monday. After that time, Paulette is forecast to become embedded in the mid-latitude flow and accelerate northeastward toward the north Atlantic. The spread in the track guidance has continued to tighten up, which increases the confidence in the official track forecast. The updated forecast has been shifted slightly westward around the time that Paulette will be near Bermuda, and it is embedded among the usually-reliable GFS, ECMWF, and HCCA model solutions. Key Messages: 1. Paulette is expected to approach Bermuda as a hurricane during the next couple of days and make its closest approach to the island on Monday. A prolonged period of strong winds, storm surge, and heavy rainfall on Bermuda beginning Sunday night is becoming more likely, and a hurricane watch could be required for the island tonight or early Saturday. 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 into the weekend. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 24.6N 53.7W 55 KT 65 MPH 12H 12/0600Z 25.9N 55.3W 60 KT 70 MPH 24H 12/1800Z 27.5N 57.5W 65 KT 75 MPH 36H 13/0600Z 28.7N 59.8W 70 KT 80 MPH 48H 13/1800Z 29.8N 62.3W 80 KT 90 MPH 60H 14/0600Z 31.1N 64.5W 85 KT 100 MPH 72H 14/1800Z 32.6N 65.3W 90 KT 105 MPH 96H 15/1800Z 36.0N 62.0W 95 KT 110 MPH 120H 16/1800Z 39.0N 56.0W 85 KT 100 MPH $$ Forecaster Berg
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