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Hurricane Teddy Forecast Discussion Number 29
2020-09-19 16:51:03| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Sat Sep 19 2020 000 WTNT45 KNHC 191450 TCDAT5 Hurricane Teddy Discussion Number 29 NWS National Hurricane Center Miami FL AL202020 1100 AM AST Sat Sep 19 2020 The overall appearance of Teddy has degraded slightly since early this morning, with the eye no longer readily apparent in satellite imagery. However, microwave data a few hours ago showed that a well- defined outer eyewall exists with a decaying partial inner eyewall. This indicates that an eyewall replacement cycle is just about complete. The objective and subjective satellite intensity estimates generally agree on an intensity of 98-102 kt, but out of respect for the completing eyewall replacement cycle the initial intensity is set to a slightly more generous 105 kt. Teddy will be moving over slightly cooler waters caused by upwelling from Paulette over the next day or so and this should cause the hurricane to slowly weaken. However, in about 36 h the cyclone's wind field is forecast to begin expanding as it interacts with an approaching frontal system. Around 48-60 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 the post-tropical cyclone quickly weakening once the transition is complete. The SHIPS guidance and global model simulated satellite imagery tend to agree that the extratropical transition should be completed just after 72 h. The latest NHC intensity forecast was nudged downward slightly mainly due to the change in the initial intensity, and is close to the HFIP corrected consensus HCCA. The hurricane continues its northwestward movement, now at 12 kt. The track forecast for Teddy remains essentially unchanged and is in the middle of tightly clustered guidance. Teddy is expected to turn northward to north-northeastward Sunday morning 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 through much of Monday. A slight turn to the north then perhaps the north- northwest 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 afternoon or 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 19/1500Z 26.0N 59.0W 105 KT 120 MPH 12H 20/0000Z 27.3N 60.4W 100 KT 115 MPH 24H 20/1200Z 28.8N 61.7W 95 KT 110 MPH 36H 21/0000Z 30.4N 62.2W 90 KT 105 MPH 48H 21/1200Z 33.1N 61.6W 90 KT 105 MPH 60H 22/0000Z 37.1N 61.2W 90 KT 105 MPH 72H 22/1200Z 40.8N 61.8W 80 KT 90 MPH 96H 23/1200Z 47.0N 59.8W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 24/1200Z 52.9N 51.1W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Latto
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