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Tropical Storm Paulette Forecast Discussion Number 23
2020-09-12 16:56:51| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Sat Sep 12 2020 000 WTNT42 KNHC 121456 TCDAT2 Tropical Storm Paulette Discussion Number 23 NWS National Hurricane Center Miami FL AL172020 1100 AM AST Sat Sep 12 2020 Paulette's structure is going through a bit of an evolution as the deep-layer shear backs from southwesterly to southeasterly. Most of the deep convection had waned earlier this morning, but new convection is beginning to develop near the center as the cyclone reconstitutes itself. For now, the initial intensity remains 60 kt. An overnight AMSR microwave pass showed that Paulette has well-defined low-level banding features, and this structure should allow the cyclone to strengthen as vertical shear falls below 10 kt during the next 12-24 hours. Strengthening is anticipated to continue through day 3, and after that time, gradual weakening is possible due to increasing southwesterly shear. The intensity guidance has been fairly stable for the past few forecast cycles, and no significant changes were required to this new NHC intensity forecast, which lies close to the HCCA model and just a bit above the intensity consensus. Paulette is likely to be strengthening while it makes its closest approach to Bermuda in about 48 hours, and the GFS-based SHIPS and HWRF models each suggest that there is a possibility of it becoming a major hurricane in 72 hours. Paulette is moving northwestward (310/13 kt), with a break in the subtropical ridge located due north of the storm. The ridge may strengthen briefly over the next day or so, causing Paulette to move west-northwestward for a short time, but it should resume the northwestward motion by late Sunday. After that time, an approaching longwave trough over the northeastern United States will erode the ridge eastward, causing Paulette to recurve sharply toward the north and then northeast between days 2 and 3. The hurricane is then expected to accelerate east-northeastward toward the north Atlantic on days 4 and 5, embedded within the mid-latitude flow. The track guidance is well clustered and has not shown any significant shifts over the past few forecast cycles. Therefore, the new NHC track forecast is similar to the previous one. Key Messages: 1. Paulette is expected to approach Bermuda as a hurricane on Sunday and be near the island Sunday night and Monday. A prolonged period of strong winds, storm surge, and heavy rainfall is expected on Bermuda beginning late Sunday evening, and a hurricane warning has been issued for the island. Preparations to protect life and property should be rushed to completion. 2. Swells produced by Paulette are affecting portions of the Leeward Islands, the Greater Antilles, the Bahamas, and Bermuda, and are expected to spread westward to the east coast of the United States during the next day or two. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 27.5N 57.2W 60 KT 70 MPH 12H 13/0000Z 28.5N 59.1W 65 KT 75 MPH 24H 13/1200Z 29.5N 61.4W 75 KT 85 MPH 36H 14/0000Z 30.8N 63.6W 80 KT 90 MPH 48H 14/1200Z 32.4N 64.8W 85 KT 100 MPH 60H 15/0000Z 34.2N 64.2W 90 KT 105 MPH 72H 15/1200Z 35.8N 61.5W 95 KT 110 MPH 96H 16/1200Z 39.0N 54.5W 90 KT 105 MPH 120H 17/1200Z 42.0N 47.0W 75 KT 85 MPH $$ Forecaster Berg
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