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Hurricane Michael Forecast Discussion Number 9
2018-10-08 22:41:49| National Hurricane Center (Atlantic)
Issued at 400 PM CDT Mon Oct 08 2018 000 WTNT44 KNHC 082041 TCDAT4 Hurricane Michael Discussion Number 9 NWS National Hurricane Center Miami FL AL142018 400 PM CDT Mon Oct 08 2018 Data from an Air Force Reserve hurricane hunter aircraft that was in the storm until about 1700 UTC continued to indicate that the hurricane was deepening. The pressure had fallen to 978 mb on the final fix, but the aircraft was still not able to sample the northeastern portion of the storm due to the close proximity of land. The initial intensity has been increased to 70 kt based on a blend of Dvorak satellite classifications and the continued deepening that was observed. The upper-level outflow has gradually improved over Michael but it is still somewhat restricted over the western portion of the storm. There has been no significant change to the intensity forecast thinking. The moderate shear that has been affecting the cyclone is not expected to prevent strengthening while Michael moves over the warm waters of the eastern Gulf of Mexico. Although the statistical guidance is somewhat lower this cycle, the regional hurricane and global models still favor steady to rapid strengthening, and the NHC forecast is closest to the Florida State Superensemble and the HFIP corrected consensus model. Aircraft and satellite fixes show that Michael has been wobbling as it moves generally northward. Smoothing through the wobbles gives a long-term initial motion estimate of 355/8 kt. Michael is forecast to move north-northwestward to northward between a deep-layer ridge over the western Atlantic and a trough over the west-central United States. The trough is forecast move eastward, causing Michael to turn northeastward in 36 to 48 hours, and the cyclone should then accelerate northeastward as it enters the mid-latitude westerly flow. The 1200 UTC dynamical models have converged on both the track and forward speed through the first 48 to 72 hours. The updated NHC track has been nudged slightly westward through 48 hours to be closer to the latest consensus aids. It should be noted that the location and magnitude of peak storm surge flooding is very sensitive to small changes in the track, intensity, and structure of the hurricane. Since there is still uncertainty in all of these parameters, the official NHC storm surge forecast and watch/warning areas includes various plausible scenarios. Regardless of the eventual track and intensity of Michael, life-threatening storm surge inundation is expected along portions of the Florida Panhandle and Big Bend/Nature Coast, and the storm surge watch has been upgraded to a storm surge warning for parts of this area. The NOAA G-IV aircraft is conducting a synoptic surveillance mission over the Gulf of Mexico and dropsondes from that mission will be assimilated into the 0000 UTC numerical models runs. Key Messages: 1. Life-threatening storm surge is likely along portions of the coasts of the Florida Panhandle, Big Bend, and Nature Coast, and a storm surge warning is in effect for these areas. Residents in these areas should follow all advice given by their local officials. 2. A hurricane warning has been issued for portions of the Florida Gulf Coast, and everyone in these areas should prepare for life-threatening winds associated with the core of Michael. Damaging winds will also extend inland across portions of the Florida Panhandle, southern Georgia, and southeast Alabama as Michael moves inland. 3. Heavy rainfall from Michael could produce life-threatening flash flooding from the Florida Panhandle and Big Bend region into portions of Georgia and South Carolina. 4. Hurricane conditions will continue in portions of western Cuba through this evening, where a hurricane warning is in effect. 5. Michael is expected to produce heavy rainfall and flash flooding over portions of western Cuba and the northeastern Yucatan Peninsula of Mexico during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 08/2100Z 22.2N 85.2W 70 KT 80 MPH 12H 09/0600Z 23.7N 85.7W 85 KT 100 MPH 24H 09/1800Z 25.7N 86.4W 95 KT 110 MPH 36H 10/0600Z 27.9N 86.6W 105 KT 120 MPH 48H 10/1800Z 30.2N 85.8W 100 KT 115 MPH...NEAR THE COAST 72H 11/1800Z 34.5N 80.5W 45 KT 50 MPH...INLAND 96H 12/1800Z 39.8N 68.8W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 13/1800Z 46.2N 50.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown
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