|
Show Selection: |
| #1018215 (Received by flhurricane at: 4:51 PM 21.Sep.2020) TCDAT5 Hurricane Teddy Discussion Number 38 NWS National Hurricane Center Miami FL AL202020 500 PM AST Mon Sep 21 2020 Teddy is gradually losing tropical characteristics with weaker deep convection near the center and more convective asymmetry. The initial wind speed is kept at 80 kt, assuming any decrease in organization has been offset by the doubling of the forward speed since the last advisory. Note that Dvorak estimates are likely to underestimate the true maximum winds in this extratropical transition situation. The hurricane is now moving quickly northward as a mid-latitude trough picks up the cyclone. All of the guidance show Teddy strengthening overnight due to a baroclinic energy infusion from this trough and increased instability from the warmer waters of the Gulf Stream/North Atlantic. Afterward, Teddy should lose its baroclinic forcing and move over cooler water late Tuesday, causing weakening while it accelerates to the north-northeast across eastern Nova Scotia, the Gulf of St. Lawrence and Newfoundland before dissipating in 3-4 days. No significant changes were made to the track forecast except for a westward shift beyond 48 hours. While there is some uncertainty about the exact status of Teddy near Nova Scotia, since much of the model guidance keeps the cyclone with a warm core and some convection, it doesn`t change the hazards much with significant chances of high winds, heavy rain, storm surge and destructive waves for the south coast of Nova Scotia. Teddy`s size will likely double during the next couple of days as it moves northward and interacts with the aforementioned trough. Gale-force winds are likely along portions of the near shore waters of the northeast United States. Please see products from your local office for more information about marine hazards, including extremely dangerous rip currents expected over much of the western Atlantic beaches. Key Messages: 1. 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 direct impacts from wind, rain, and storm surge are expected. Tropical Storm Watches and Warnings are in effect for portions of Nova Scotia, Prince Edward Island and Newfoundland. 2. Very 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 are expected to cause life-threatening surf and rip current conditions. 3. Heavy rainfall across Atlantic Canada is expected with Teddy between Tuesday and Thursday after it becomes a strong post-tropical cyclone. FORECAST POSITIONS AND MAX WINDS INIT 21/2100Z 33.2N 62.0W 80 KT 90 MPH 12H 22/0600Z 36.5N 62.5W 90 KT 105 MPH 24H 22/1800Z 39.5N 63.7W 80 KT 90 MPH 36H 23/0600Z 42.2N 63.2W 70 KT 80 MPH 48H 23/1800Z 46.5N 61.5W 60 KT 70 MPH...POST-TROP/EXTRATROP 60H 24/0600Z 50.5N 58.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 72H 24/1800Z 54.5N 53.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 25/1800Z...DISSIPATED $$ Forecaster Blake |