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| #1017835 (Received by flhurricane at: 4:39 PM 19.Sep.2020) TCDAT5 Hurricane Teddy Discussion Number 30 NWS National Hurricane Center Miami FL AL202020 500 PM AST Sat Sep 19 2020 The earlier eyewall replacement cycle occuring in Teddy since last night appears to have completed. There is now a more pronounced outer ring of convection noted in satellite and microwave imagery, and a large ragged eye is beginning to appear in the satellite images. The latest satellite intensity estimates from TAFB and UW-CIMSS ADT support keeping the initial intensity at 105 kt. A U.S. Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the hurricane later this evening. There is no change to the forecast intensity and structure for Teddy. The hurricane will be moving over slightly cooler waters caused by upwelling from Paulette over the next 24h and this should cause the hurricane to slowly weaken. However, in about 36 h as the system passes east of Bermuda, the cyclone`s wind field is forecast to begin rapidly expanding as it interacts with an approaching frontal system. By 48 h, vertical wind shear is expected to dramatically increase as Teddy becomes embedded in the flow around a sharp mid-latitude upper-level trough. The interaction of the cyclone with both the front and trough should cause Teddy to begin an extratropical transition, with this transition expected to be completed by 72 h. This transition timing is in agreement with the global models. Once this transition occurs, the post-tropical cyclone is forecast to rapidly weaken, but is still expected to be a powerful extratropical cyclone as it approaches Atlantic Canada early next week. The latest NHC intensity forecast is little changed from the previous one and is near the SHIPS and HFIP corrected consensus HCCA. Teddy jogged a little west of track today, but the longer term motion is still northwestward at about 11 kt. This motion is expected to continue through most of the day Sunday. Teddy should then turn northward to north-northeastward late Sunday as it approaches a frontal system over the western Atlantic. This pattern should steer the hurricane east of Bermuda, though the hurricane`s large wind field means that the island will still likely experience tropical storm conditions beginning by Sunday evening and continuing into Monday evening. A slight turn to the north then perhaps the north- northwest with a faster forward motion should occur Monday night into Tuesday as Teddy pivots around the upper trough. By Tuesday night, the cyclone is forecast to turn northeastward as the upper trough to its southwest begins to lift into the higher latitudes. Teddy is producing an extensive area of large waves and swells which are impacting much of the western Atlantic basin. See the Key Messages below. Key Messages: 1. While the center of Teddy is forecast to move east of Bermuda late Sunday or Monday, tropical storm conditions are likely on the island beginning Sunday 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 19/2100Z 26.7N 60.2W 105 KT 120 MPH 12H 20/0600Z 27.9N 61.6W 100 KT 115 MPH 24H 20/1800Z 29.1N 62.7W 95 KT 110 MPH 36H 21/0600Z 30.7N 62.7W 90 KT 105 MPH 48H 21/1800Z 33.6N 61.8W 90 KT 105 MPH 60H 22/0600Z 38.3N 61.9W 85 KT 100 MPH 72H 22/1800Z 41.9N 62.7W 80 KT 90 MPH...POST-TROP/EXTRATROP 96H 23/1800Z 47.7N 58.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 24/1800Z 55.5N 45.5W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Latto |