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Hurricane Teddy Forecast Discussion Number 19
2020-09-17 04:43:07| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Wed Sep 16 2020 000 WTNT45 KNHC 170243 TCDAT5 Hurricane Teddy Discussion Number 19 NWS National Hurricane Center Miami FL AL202020 1100 PM AST Wed Sep 16 2020 Teddy has been a perplexing hurricane thus far. The infrared satellite presentation appears rather impressive, with the center embedded beneath a Central Dense Overcast with cloud tops as cold as -85 degrees Celsius. Despite the presentation, however, Dvorak estimates from TAFB and SAB are a consensus T4.5/77 kt, and objective estimates range between 70-75 kt. Teddy's initial intensity is therefore set just above these estimates at 80 kt. A recent ASCAT pass indicated that Teddy's center is a little farther to the southwest than previously estimated. However, the long-term motion remains toward the northwest (315/11 kt). The track forecast remains straightforward the the next 3 days, with the guidance in good agreement that a mid-tropospheric high over the central Atlantic will drive the hurricane northwestward toward the western Atlantic. There is a little more spread among the track models on days 4 and 5, related to timing differences on exactly where and how fast Teddy begins to recurve ahead of an approaching mid-latitude trough coming from the northeastern United States. The new NHC track forecast has been nudged westward during the first 3 days to account for the initial position adjustment, but otherwise it's still close to the previous prediction even with the increasing model spread on days 4 and 5. An upper-level trough situated to the northwest of Teddy is causing about 10-15 kt of deep-layer southwesterly shear over the hurricane, and some model analyses suggest that there could be stronger shear in a layer below the level of the upper-level outflow. The deep-layer shear is expected to increase a bit during the next day or so, but this should be offset by a favorable thermodynamic environment, allowing for some intensification during that time. The shear might relax by days 3 and 4, but then the thermodynamic environment becomes a little less conducive for strengthening. In particular, Teddy may move over the cold wake of Hurricane Paulette, and the SHIPS guidance indicates that relatively warm upper-level temperatures could be a negative factor. All that said, the NHC intensity forecast lies near the top end of the guidance envelope, showing Teddy peaking in intensity in a couple of days and then only gradually weakening through the end of the forecast period. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 17.8N 51.5W 80 KT 90 MPH 12H 17/1200Z 18.9N 52.6W 85 KT 100 MPH 24H 18/0000Z 20.3N 54.1W 95 KT 110 MPH 36H 18/1200Z 21.8N 55.6W 100 KT 115 MPH 48H 19/0000Z 23.5N 57.1W 100 KT 115 MPH 60H 19/1200Z 25.3N 59.1W 95 KT 110 MPH 72H 20/0000Z 27.0N 61.1W 95 KT 110 MPH 96H 21/0000Z 30.0N 64.0W 90 KT 105 MPH 120H 22/0000Z 35.0N 64.0W 90 KT 105 MPH $$ Forecaster Berg
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