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Hurricane Florence Forecast Discussion Number 24
2018-09-05 10:48:38| National Hurricane Center (Atlantic)
Issued at 500 AM AST Wed Sep 05 2018 485 WTNT41 KNHC 050848 TCDAT1 Hurricane Florence Discussion Number 24 NWS National Hurricane Center Miami FL AL062018 500 AM AST Wed Sep 05 2018 Conventional satellite enhanced BD-curve infrared imagery and a 0511 UTC GMI color composite microwave pass reveal improved inner core structure with impressive outer banding over the eastern semicircle. Dvorak intensity estimates have again increased, and the initial intensity is once more increased to 90 kt, which also agrees with the latest SATCON analysis. This intensity forecast is still a bit murky. The deterministic models show increasing southwesterly vertical shear and a less than favorable mid-tropospheric thermodynamic environment affecting the tropical cyclone over the next 48 hours. This less-than-conducive environment should induce weakening during this time frame. Thereafter, and through the remaining forecast, most of the models show a mid- to upper-level low developing to the south of Florence in the base of the mid- Atlantic deep-layer trough, which should promote a somewhat more favorable diffluent upper wind pattern. This more conducive upper wind pattern, and increasing sea surface temperatures, is expected to cause Florence to restrengthen. The NHC forecast is a little bit higher than the previous one between the 48 and 96 hr periods to agree more with the IVCN and NOAA-HCCA consensus forecasts. Florence is estimated to be moving northwestward, or 305/11 kt, which appears to be a temporary trochoidal eyewall wobble. A turn back toward the west-northwest is expected later today, and this general motion is expected to continue through day 4 while the hurricane is steered by the southwestern periphery of the subtropical ridge. By the end of the forecast period, Florence is expected to turn northwestward and slow down as it enters a break in the ridge. The ECMWF model track forecast has shifted significantly toward the left this evening, closer to the other global models and their ensemble means, indicating less steering influence from the predicted growing weakness in the subtropical ridge. Subsequently, an adjustment to the left of of the previous advisory, beyond 48 hours, was made in order to nudge closer to the guidance suite and the consensus models. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 21.4N 44.8W 90 KT 105 MPH 12H 05/1800Z 22.2N 46.3W 90 KT 105 MPH 24H 06/0600Z 23.2N 48.2W 80 KT 90 MPH 36H 06/1800Z 24.2N 50.0W 70 KT 80 MPH 48H 07/0600Z 24.9N 51.5W 70 KT 80 MPH 72H 08/0600Z 25.6N 54.1W 75 KT 85 MPH 96H 09/0600Z 26.8N 56.3W 80 KT 90 MPH 120H 10/0600Z 28.7N 58.2W 85 KT 100 MPH $$ Forecaster Roberts
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