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Tropical Storm Sally Intermediate Advisory Number 5A
NWS National Hurricane Center Miami FL AL192020
800 PM EDT Sat Sep 12 2020
...LIFE-THREATENING STORM SURGE AND HURRICANE-FORCE WINDS
POSSIBLE ALONG PORTIONS OF THE NORTHERN GULF COAST EARLY NEXT
SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
ABOUT 45 MI...70 KM W OF NAPLES FLORIDA
ABOUT 455 MI...735 KM ESE OF THE MOUTH THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Watch is in effect for...
* Mouth of the Mississippi River to the Alabama/Florida Border
* Lake Pontchartrain, Lake Maurepas, and Lake Borgne
* Mobile Bay
A Hurricane Watch is in effect for...
* Grand Isle Louisiana to the Alabama/Florida border
* Lake Pontchartrain and Lake Maurepas including metropolitan New
A Tropical Storm Watch is in effect for...
* Alabama/Florida Border to Ochlockonee River Florida
A Storm Surge Watch means there is a possibility of life-
threatening inundation, from rising water moving inland from the
coastline, in the indicated locations during the next 48 hours.
For a depiction of areas at risk, please see the National Weather
Service Storm Surge Watch/Warning Graphic, available at
A Hurricane Watch means that hurricane conditions are possible
within the watch area. A watch is typically issued 48 hours
before the anticipated first occurrence of tropical-storm-force
winds, conditions that make outside preparations difficult or
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area within the next 48 hours.
For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.
DISCUSSION AND OUTLOOK
At 800 PM EDT (0000 UTC), the center of Tropical Storm Sally was
located near latitude 26.0 North, longitude 82.5 West. Sally is
moving toward the west-northwest near 8 mph (13 km/h), and a
west-northwestward or northwestward motion is expected through
Monday. On Monday night and Tuesday, a decrease in forward speed and
a turn toward the north are forecast. On the forecast track, the
center of Sally will move over the southeastern and eastern Gulf of
Mexico tonight and Sunday, move over the north-central Gulf of
Mexico Sunday night and Monday, and approach the north-central Gulf
Coast within the hurricane watch area late Monday and Tuesday.
Maximum sustained winds are near 40 mph (65 km/h) with higher
gusts. Strengthening is expected over the next couple of days, and
Sally is forecast to become a hurricane on Monday.
Tropical-storm-force winds extend outward up to 80 miles (130 km)
from the center. Marco Island, Florida, recently reported a
sustained wind of 31 mph (50 km/h) and wind gust of 39 mph (63
The estimated minimum central pressure based on surface
observations is 1003 mb (29.62 inches).
HAZARDS AFFECTING LAND
Key messages for Sally can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC.
STORM SURGE: The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline. The water could
reach the following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide...
Mouth of the Mississippi River to Ocean Springs, MS including Lake
Ocean Springs, MS to MS/AL Border...4-6 ft
MS/AL Border to AL/FL Border, including Mobile Bay...2-4 ft
Lake Pontchartrain and Lake Maurepas...2-4 ft
AL/FL Border to Chassahowitzka, FL, including Pensacola Bay,
Choctawhatchee Bay, and Saint Andrew Bay...1-3 ft
The deepest water will occur along the immediate coast near and to
the right of the landfall location, where the surge will be
accompanied by large and damaging waves. Surge-related flooding
depends on the relative timing of the surge and the tidal cycle,
and can vary greatly over short distances. For information
specific to your area, please see products issued by your local
National Weather Service forecast office.
WIND: Hurricane conditions are possible within the hurricane watch
area by early Tuesday, with tropical storm conditions possible
within the watch area by Monday.
Wind gusts to tropical-storm force are possible across the
southern portion of the Florida peninsula through this evening,
especially over the Florida Keys.
RAINFALL: Sally is expected to produce additional rainfall amounts
of 2 to 4 inches over southern Florida and the Florida Keys through
tonight. Rainfall amounts of 2 to 4 inches with isolated amounts
of 6 inches are expected along the west coast of Florida through
Sunday. This rainfall will produce flash and urban flooding across
southern Florida and prolong high flows and ongoing minor flooding
on rivers across central Florida.
Sally is expected to produce rainfall amounts of 5 to 10 inches
across the Florida Panhandle, and 6 to 12 inches with isolated
amounts of 18 inches over the central Gulf Coast from Sunday into
the middle of next week. Sally is expected to be a slow moving
system that will continue to produce heavy rainfall and considerable
flooding near the central Gulf Coast through the middle of next
week. Flash, urban and rapid onset flooding along small streams and
minor to moderate flooding on rivers is likely.
SURF: Swells are expected to spread northward along the west-
central coast of Florida and reach the Florida Panhandle and
the northern Gulf Coast during the next couple of days. These
swells are likely to cause life-threatening surf and rip current
conditions. Please consult products from your local weather office.
TORNADOES: A tornado or two are possible through tonight over south
Next complete advisory at 1100 PM EDT.