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Hurricane Teddy Forecast Discussion Number 22
2020-09-17 22:58:21| National Hurricane Center (Atlantic)
Issued at 500 PM AST Thu Sep 17 2020 588 WTNT45 KNHC 172058 TCDAT5 Hurricane Teddy Discussion Number 22 NWS National Hurricane Center Miami FL AL202020 500 PM AST Thu Sep 17 2020 Teddy has intensified quickly today, with the cyclone now having a more symmetrical appearance while the eye has become mostly clear. The deep convection with cloud tops ranging from -60 to -75 degrees have surrounded the eye for much of the day, and there are well-defined outflow channels to the south and east of the hurricane. Both NOAA and US Air Force Reserve Hurricane Hunter aircraft have spent time investigating Teddy today as it has been intensifying and have been able to provide very useful data in determining both the size and strength of the hurricane. The peak SFMR winds measured by the aircraft this afternoon were 113 kt, while the peak 700 mb flight-level winds were 130 kt. Based on a reduction to 117 kt from 700 mb, and assuming some slight undersampling may be occurring, the initial intensity has been raised to 120 kt. The hurricane is expected to remain in an environment of low-moderate shear while over warm waters for the 48 h or so. And since the period of rapid strengthening of Teddy appears to be ongoing, the hurricane is expected to strengthen some more into tonight. Once this round of intensification completes, there will likely be some fluctuations in strength due to eyewall replacement cycles and other short term changes in structure. After 48 h, the path of Teddy should take it over some cooler waters caused by upwelling from Hurricane Paulette last week. This should cause the cyclone to slowly weaken. By 96 h, vertical wind shear is forecast to increase ahead of an approaching mid-latitude trough and associated frontal boundary. This should hasten the weakening trend of Teddy. By 120 h, the hurricane is expected to have crossed the 26 degree SST isotherm, and will begin to interact with the aforementioned mid-latitude system causing it to begin an extratropical transition that may or may not be completed by the end of the forecast period. The latest NHC intensity forecast has been increased due to the higher initial intensity, and the forecast trends fit well with the various intensity consensus and SHIPS guidance. Teddy continues its northwestward motion, now at 11 kt. The track guidance is in very good agreement on a continuation of this motion for the next 72 h as the cyclone is steered by a mid-level ridge over the central Atlantic. The model guidance has come into better agreement on the evolution of the large scale features later on in the forecast period as the hurricane is expected to recurve ahead of the approaching mid-latitude trough moving off the coast of the eastern United States in a few days. The new NHC track forecast is little changed from the previous one, and is in the middle of the track guidance. On the forecast track, Teddy will make its closest approach to Bermuda Sunday night into Monday. Key Messages: 1. Teddy is expected to approach Bermuda as a hurricane this weekend and make its closest approach to the island late Sunday or Monday. While the exact details of Teddy's track and intensity near the island are not yet known, the risk of strong winds, storm surge, and heavy rainfall on Bermuda is increasing. 2. Large swells produced by Teddy are expected to affect portions of the Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, and the southeastern United States late this week and into the weekend. These swells could cause life-threatening surf and rip current conditions. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 20.1N 54.1W 120 KT 140 MPH 12H 18/0600Z 21.2N 55.2W 130 KT 150 MPH 24H 18/1800Z 22.8N 56.6W 125 KT 145 MPH 36H 19/0600Z 24.5N 58.1W 125 KT 145 MPH 48H 19/1800Z 26.3N 59.9W 120 KT 140 MPH 60H 20/0600Z 28.0N 62.1W 110 KT 125 MPH 72H 20/1800Z 29.5N 63.3W 105 KT 120 MPH 96H 21/1800Z 33.9N 63.0W 95 KT 110 MPH 120H 22/1800Z 41.3N 62.0W 80 KT 90 MPH $$ Forecaster Latto
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