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Hurricane Sally Forecast Discussion Number 19
2020-09-16 04:57:52| National Hurricane Center (Atlantic)
Issued at 1000 PM CDT Tue Sep 15 2020 000 WTNT44 KNHC 160257 TCDAT4 Hurricane Sally Discussion Number 19 NWS National Hurricane Center Miami FL AL192020 1000 PM CDT Tue Sep 15 2020 Observations from an Air Force Hurricane Hunter aircraft and WSR-88D Doppler radar data indicate some strengthening. The eye has become a little better defined on the radar, and the central pressure has fallen to 972 mb. The eye has also become evident on recent IR imagery. Using a blend of flight-level and SFMR-observed surface winds, along with the Doppler velocities, gives a current intensity estimate of 75 kt. Given the recent trends, the official forecast allows for some more intensification before landfall, which is likely to occur in less than 12 hours. Rapid weakening will occur after the center moves inland, and the system should become a remnant low in a couple of days. This is consistent with the model guidance. Radar and aircraft center fixes indicate that the motion is now north-northeastward, or 020/2 kt. Sally should move north-northeastward, and then northeastward, with a gradual increase in forward speed, along the northwestern side of a weak mid-level high pressure area for the next couple of days. Then, as the system approaches the westerly flow at higher latitudes, the cyclone should turn toward the east-northeast with a slight further increase in forward speed until becoming a dissipating remnant low near the southeast U.S. coast in 2-3 days. The official forecast is close to the latest corrected dynamical model consensus, HCCA, prediction. KEY MESSAGES: 1. Historic, life-threatening flash flooding due to rainfall is likely through Wednesday along and just inland of the coast from the Florida Panhandle west of the Apalachicola River to the Alabama/Mississippi border. Widespread moderate to major river flooding is forecast across the Florida Panhandle and southern Alabama. Significant flash and urban flooding, as well as widespread minor to moderate river flooding, is likely across inland portions of Mississippi and Alabama, and into Georgia and the western Carolinas this week. 2. Life-threatening storm surge is expected along portions of the coastline from Alabama to the western Florida Panhandle, including Mobile Bay. 3. Hurricane conditions are expected this evening and overnight within portions of the Hurricane Warning area along the Mississippi and Alabama coastlines and the western Florida Panhandle. FORECAST POSITIONS AND MAX WINDS INIT 16/0300Z 29.8N 87.8W 75 KT 85 MPH 12H 16/1200Z 30.3N 87.5W 80 KT 90 MPH...ON THE COAST 24H 17/0000Z 31.2N 86.8W 40 KT 45 MPH...INLAND 36H 17/1200Z 32.0N 85.7W 30 KT 35 MPH...INLAND 48H 18/0000Z 32.9N 83.9W 25 KT 30 MPH...INLAND 60H 18/1200Z 33.6N 81.5W 20 KT 25 MPH...INLAND 72H 19/0000Z 34.0N 79.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 20/0000Z...DISSIPATED $$ Forecaster Pasch
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