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| #1017979 (Received by flhurricane at: 11:00 AM 20.Sep.2020) TCDAT5 Hurricane Teddy Discussion Number 33 NWS National Hurricane Center Miami FL AL202020 1100 AM AST Sun Sep 20 2020 The satellite signature of Teddy has degraded from an eye pattern overnight into a central dense overcast this morning. Air Force Reserve Hurricane Hunter aircraft data indicate that the hurricane has weakened, and the initial wind speed is set to 90 kt, perhaps generously. The aircraft data does still show that Teddy remains a large hurricane, with hurricane-force winds extending outward in the northeastward quadrant to about 70 n mi. While the forecast intensity does not change much over the next couple of days, the hurricane should undergo significant changes during that time. Teddy should not lose any more strength by late today due to favorable positioning with an approaching trough, and the gale-force winds should greatly expand due to this trough interaction. In 2 or 3 days, after the system occludes and becomes post-tropical, the cyclone should weaken because of a loss of extratropical forcing while over the cooler water south of Nova Scotia. Eventually Teddy will probably get absorbed by a larger extratropical low around day 5. Model guidance is fairly tightly packed around the official wind forecast, which leans on the global models given the substantial extratropical contributions, plus or minus 5 kt throughout the forecast period. The hurricane has resumed a northwestward motion or 320/8 kt. Teddy is likely to turn northward today and north-northeastward tomorrow due to the aforementioned trough. By early Tuesday, the cyclone should turn back to the north-northwest as it rotates around the same trough, then turn northeastward early Wednesday ahead of yet another trough moving into from eastern Canada. Although the forecast evolution is complex, model guidance is in remarkably good agreement, and no substantial changes were made to the previous forecast. Regardless of the details, every model has a rather large and strong post-tropical cyclone south of Nova Scotia in about 3 days. 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 this evening 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 early next week, where there is an increasing risk of direct impacts from wind, rain, and storm surge. Residents there should closely monitor the progress of Teddy and updates to the forecast. 3. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, 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 20/1500Z 28.3N 62.8W 90 KT 105 MPH 12H 21/0000Z 29.2N 63.4W 85 KT 100 MPH 24H 21/1200Z 31.0N 62.9W 85 KT 100 MPH 36H 22/0000Z 34.8N 62.1W 85 KT 100 MPH 48H 22/1200Z 38.8N 63.0W 85 KT 100 MPH 60H 23/0000Z 41.7N 63.4W 75 KT 85 MPH...POST-TROP/EXTRATROP 72H 23/1200Z 44.5N 62.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 96H 24/1200Z 53.0N 53.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 120H 25/1200Z 60.5N 39.5W 35 KT 40 MPH...POST-TROP/EXTRATROP $$ Forecaster Blake |