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Hurricane Teddy Forecast Discussion Number 35
2020-09-21 04:51:38| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Sun Sep 20 2020 000 WTNT45 KNHC 210251 TCDAT5 Hurricane Teddy Discussion Number 35 NWS National Hurricane Center Miami FL AL202020 1100 PM AST Sun Sep 20 2020 Teddy's satellite presentation has changed little during the past several hours albeit some warming of the eye. The 53rd Air Force Reserve hurricane hunters recorded a central pressure this evening of 963 mb, unchanged from the previous mission, and the Dvorak subjective intensity estimates haven't changed either. Therefore, the initial intensity is held at 90 kt for this advisory. There is a chance, within the next 24 hours, that Teddy could strengthen a bit due to dynamic forcing as a result of the approaching baroclinic zone moving off of the northeast coast of the United States. In Fact, the HCCA intensity model shows a peak of 95 kt at the 24 hour period. By Tuesday afternoon, however, increasing southwesterly shear associated with the rapidly approaching mid-latitude major shortwave trough, from the northwest, should induce weakening. Because Teddy is a very large and strong tropical cyclone, only gradual weakening is predicted. By mid period, the large-scale models agree that Teddy will merge with the aforementioned trough and associated frontal zone and complete its extratropical cyclone transition south of Nova Scotia Tuesday evening. Teddy is still forecast to be a very large and powerful extratropical cyclone as it approaches, Nova Scotia at that time. Wind, rain, surf and storm surge hazards are expected to spread over an extensive portion of Atlantic Canada mid-week. The forecast wind radii at the 36 hour period and beyond, are based on the RVCN Wind Radii Consensus model that consists of a bias-corrected average of the global and regional models. The initial motion is estimated to be north-northwestward, or 5 kt. The hurricane is likely to turn northward Monday morning and continue in this general motion through Wednesday morning. Around the 60 hour period, a turn north-northeastward is forecast ahead of yet another mid-latitude pulse moving into eastern Canada. No significant adjustments were made to the NHC track forecast and it lies in between the surprisingly tightly clustered model guidance. Extremely dangerous surf conditions with 20-ft waves have been reported on the south shore of Bermuda, and officials are encouraging residents to avoid going into or near the water. Key Messages: 1. The center of Teddy is forecast to move east of Bermuda on Monday. Tropical storm conditions are likely on the island beginning overnight and could continue into Monday evening. 2. Teddy is expected to transition to a powerful post-tropical cyclone as it moves near or over portions of Atlantic Canada late Tuesday through Thursday, where there is an increasing risk of direct impacts from wind, rain, and storm surge. A Tropical Storm Watch is in effect for portions of Nova Scotia, and heavy rainfall across Atlantic Canada is expected with Teddy between Tuesday and Thursday after it becomes a strong post-tropical cyclone. 3. Large swells produced by Teddy are expected to affect portions of Bermuda, the Leeward Islands, the Greater Antilles, the Bahamas, the east coast of the United States, and Atlantic Canada during the next few days. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 21/0300Z 29.4N 63.6W 90 KT 105 MPH 12H 21/1200Z 30.9N 63.5W 90 KT 105 MPH 24H 22/0000Z 34.8N 62.9W 95 KT 110 MPH 36H 22/1200Z 38.5N 63.8W 90 KT 105 MPH 48H 23/0000Z 41.3N 64.2W 80 KT 90 MPH...POST-TROP/EXTRATROP 60H 23/1200Z 44.5N 62.8W 65 KT 75 MPH...POST-TROP/INLAND 72H 24/0000Z 48.6N 59.9W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 25/0000Z 57.4N 47.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 26/0000Z...ABSORBED BY A LARGER LOW $$ Forecaster Roberts
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