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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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