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Hurricane Teddy Forecast Discussion Number 20
2020-09-17 10:54:10| National Hurricane Center (Atlantic)
Issued at 500 AM AST Thu Sep 17 2020 000 WTNT45 KNHC 170854 TCDAT5 Hurricane Teddy Discussion Number 20 NWS National Hurricane Center Miami FL AL202020 500 AM AST Thu Sep 17 2020 Several passive microwave overpasses have revealed that Teddy has developed a 25-nmi-wide closed eye, while GOES-16 infrared satellite data shows significant cooling of the cloud tops surrounding a ragged eye feature. As a result, satellite intensity estimates have increased, thus Teddy's intensity has been increased to 90 kt based on a Dvorak classification of T5.0/90 kt from SAB and a recent UW-CIMSS adjusted-ADT value of T5.7/105 kt. The initial motion estimate based on the microwave satellite fixes is 305/10 kt. As described in previous discussions, the track forecast and reasoning both remain straightforward and unchanged for the next 72 h. The latest NHC model guidance is in excellent agreement that a deep-layer ridge situated over the central Atlantic will force Teddy on a northwestward track toward the western Atlantic. There is a little less divergence among the models on days 4 and 5 then on previous runs, and this difference remains related timing differences on where and how fast the hurricane begins to recurve ahead of an approaching mid-latitude trough and frontal system moving off the coast of the eastern United States in about 3 days. The new NHC track forecast is close to the previous advisory track now that it appears that the models have settled down, and lies close to the consensus models TVCA, HCCA, and FSSE. The overall environmental conditions appear to be conducive for Teddy to continue to at least gradually strengthen for the next 36-48 hours. However, with sea-surface temperatures expected to be near 30 deg C in 48-72 hours when the vertical shear is going to be near zero, the intensity forecast at that time could be too low. For now, the official intensity forecast lies near the upper end of the guidance envelope, and shows Teddy's intensity leveling off after 36 hours due to the very dry environment that the hurricane will be moving through, which could disrupt the inner-core convective pattern and eye feature. FORECAST POSITIONS AND MAX WINDS INIT 17/0900Z 18.3N 52.3W 90 KT 105 MPH 12H 17/1800Z 19.5N 53.5W 90 KT 105 MPH 24H 18/0600Z 20.9N 54.9W 100 KT 115 MPH 36H 18/1800Z 22.5N 56.5W 105 KT 120 MPH 48H 19/0600Z 24.3N 58.2W 105 KT 120 MPH 60H 19/1800Z 26.1N 60.2W 100 KT 115 MPH 72H 20/0600Z 27.6N 62.0W 100 KT 115 MPH 96H 21/0600Z 30.7N 64.0W 95 KT 110 MPH 120H 22/0600Z 36.0N 62.9W 90 KT 105 MPH $$ Forecaster Stewart
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