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Tropical Storm Gordon Forecast Discussion Number 6
2018-09-03 22:52:24| National Hurricane Center (Atlantic)
Issued at 500 PM EDT Mon Sep 03 2018 249 WTNT42 KNHC 032052 TCDAT2 Tropical Storm Gordon Discussion Number 6 NWS National Hurricane Center Miami FL AL072018 500 PM EDT Mon Sep 03 2018 Data from an earlier Air Force Reserve reconnaissance mission, along with Doppler velocity data from the Miami radar, indicate that Gordon has strengthened a little more, with some these data supporting an intensity of about 50 kt. However, since the earlier 5-n mi-diameter eye has eroded and inner-core convection has become somewhat ragged, the initial intensity remains 45 kt. The initial motion estimate is 300/15 kt. The latest model guidance is still in excellent agreement on Gordon maintaining a west- northwestward to northwestward motion for the next 48-72 hours right up until landfall as a strong ridge to the north of the cyclone is forecast to remain locked in place over the southeastern U.S. and mid-Atlantic states. Although the guidance has shifted slightly back to the left, no appreciable changes were made to the previous forecast track since the models have been 'windshield-wipering' back and forth over the past 24 hours. The new NHC track forecast is similar to or a little north of the latest consensus models. Overall, Gordon's presentation in both radar and satellite imagery has steadily improved since the previous advisory. Although the inner-core structure has eroded somewhat, outer banding features have improved and now extend as far north as central and northern Florida. The GFS- and ECMWF-based SHIPS intensity models continue to indicate that westerly to northwesterly wind shear of 10-15 kt is expected to affect Gordon for the next 36 hours, a flow pattern that would generally hinder development. However, the global models' upper-level wind fields show Gordon remaining near or underneath a synoptic-scale upper-level anticyclone, a more favorable pattern that supports at least steady strengthening. Since Gordon will be moving over very warm sea-surface temperatures of about 30 C, the cyclone is forecast to reach hurricane strength in 24-36 hours, just before landfall. For that reason, a Hurricane Warning has been issued for portions of the central Gulf Coast. The NHC intensity forecast is a little above the previous advisory, and is close to a blend of the consensus models HCCA, FSSE, and IVCN. Key Messages: 1. Gordon is expected to bring life-threatening storm surge and hurricane conditions to portions of the central Gulf Coast where a Storm Surge Warning and Hurricane Warning are in effect. Residents in these areas should listen to advice from their local officials. All preparations to protect life and property should be rushed to completion, as tropical storm conditions are expected to arrive in the warning areas Tuesday afternoon or evening. 2. Heavy rainfall from Gordon will affect southern Alabama, southern Mississippi and Louisiana, where totals could reach as high as 8 inches. This rainfall could cause flash flooding. 3. Rainfall will continue across portions of South Florida and the Florida Keys through early Tuesday, where totals could reach as high as 8 inches. FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 26.2N 82.6W 45 KT 50 MPH 12H 04/0600Z 27.3N 84.8W 50 KT 60 MPH 24H 04/1800Z 28.9N 87.2W 60 KT 70 MPH 36H 05/0600Z 30.6N 89.3W 65 KT 75 MPH...INLAND 48H 05/1800Z 32.1N 91.1W 35 KT 40 MPH...INLAND 72H 06/1800Z 34.1N 93.5W 25 KT 30 MPH...INLAND 96H 07/1800Z 35.5N 94.8W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 08/1800Z 38.2N 94.8W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
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