Tropical Storm SALLY (Text)

Tropical Storm Sally Discussion Number   5
NWS National Hurricane Center Miami FL       AL192020
500 PM EDT Sat Sep 12 2020

Sally continues to gradually become better organized, with 
developing convective banding features primarily over the southern 
portion of the circulation at this time.  Upper-level outflow is 
still rather limited over the northern semicircle, possibly due to a 
weak upper low near the Georgia/Florida border.  The latter feature 
is likely to soon move away from the area, however.  Based on 
earlier scatterometer passes that showed tropical-storm-force winds 
over the Straits of Florida, the advisory intensity remains 35 kt.  
With very warm waters and a moist tropospheric environment ahead of 
Sally, strengthening seems likely.  Some increase in westerly shear 
over the northern Gulf in 48-72 hours could at least slow down the 
intensification process around that time.  The official intensity 
forecast is not far from the latest model consensus and a little 
above the previous forecast.

Fixes from an Air Force Hurricane Hurricane aircraft, radar, 
satellite, and surface observations indicate a slow, generally 
westward motion of about 280/6 kt.  A weakening mid-level high 
pressure system to the northeast of Sally should cause a generally 
west-northwestward to northwestward motion for the next few days.  
Because of the weakening steering currents, the cyclone should 
move rather slowly while it approaches the northern Gulf Coast.  
However, there is expected to be enough of a narrow north-south 
oriented ridge to the east of Sally in 3-4 days to steer the 
cyclone northward across the coast.  The official track forecast 
has been nudged just slightly west of the previous one and lies 
between the simple and corrected dynamical track model consensus 
Users are reminded to not focus on the exact details of the
track or intensity forecast as the average NHC track error at 96 h
is around 150 miles and the average intensity error is around
15 mph.  In addition, winds, storm surge, and rainfall hazards will
extend far from the center.
1. Life threatening storm surge is possible along the Gulf Coast 
beginning on Monday, and a Storm Surge Watch is in effect for areas 
outside the southeast Louisiana Hurricane and Storm Damage Risk 
Reduction System from the Mouth of the Mississippi River to the 
Alabama/Florida border. Residents in these areas should follow any 
advice given by local officials. 

2. Hurricane conditions are possible by early Tuesday from Grand 
Isle, Louisiana to the Alabama/Florida border, including 
Metropolitan New Orleans, with tropical storm conditions possible by 

3. Sally is expected to produce flash flooding across portions of 
southern Florida and prolong existing minor river flooding across 
central Florida through Sunday. Flash, urban, and minor to moderate 
river flooding is likely across portions of the central Gulf Coast 
from Sunday through the middle of next week. 

4. Tropical storm conditions are possible early next week in 
portions of the Florida Panhandle, where a Tropical Storm Watch is 
in effect.  Wind gusts to tropical-storm force could occur over 
portions of the southern Florida Peninsula and the Florida Keys this 
INIT  12/2100Z 25.7N  81.9W   35 KT  40 MPH
 12H  13/0600Z 26.4N  83.4W   40 KT  45 MPH
 24H  13/1800Z 27.3N  85.3W   50 KT  60 MPH
 36H  14/0600Z 28.0N  86.9W   60 KT  70 MPH
 48H  14/1800Z 28.5N  88.1W   70 KT  80 MPH
 60H  15/0600Z 29.0N  89.0W   75 KT  85 MPH
 72H  15/1800Z 29.7N  89.3W   75 KT  85 MPH
 96H  16/1800Z 31.1N  89.2W   55 KT  65 MPH...INLAND
120H  17/1800Z 33.1N  87.0W   30 KT  35 MPH...INLAND
Forecaster Pasch

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Page last modified: Thursday, 31-Dec-2020 12:10:01 UTC