Tropical Storm Sally Intermediate Advisory Number 7A
NWS National Hurricane Center Miami FL AL192020
800 AM EDT Sun Sep 13 2020…HEAVY RAINS FROM SALLY SPREADING NORTHWARD ALONG THE SOUTHWEST
COAST OF FLORIDA…SUMMARY OF 800 AM EDT…1200 UTC…INFORMATION
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LOCATION…27.3N 84.6W
ABOUT 155 MI…250 KM W OF PORT CHARLOTTE FLORIDA
ABOUT 300 MI…485 KM ESE OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS…50 MPH…85 KM/H
PRESENT MOVEMENT…WNW OR 300 DEGREES AT 13 MPH…20 KM/H
MINIMUM CENTRAL PRESSURE…996 MB…29.41 INCHESWATCHES AND WARNINGS
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CHANGES WITH THIS ADVISORY:None
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for…
* Port Fourchon Louisiana to the Mississippi/Alabama Border
* Lake Pontchartrain, Lake Maurepas, and Lake Borgne
A Hurricane Warning is in effect for…
* Grand Isle Louisiana to Ocean Springs Mississippi
* Lake Pontchartrain and Lake Maurepas including metropolitan New
Orleans
A Storm Surge Watch is in effect for…
* Mississippi/Alabama Border to the Alabama/Florida Border
A Hurricane Watch is in effect for…
* East of Ocean Springs to the Alabama/Florida Border
A Tropical Storm Warning is in effect for…
* East of Ocean Springs to Indian Pass
A Tropical Storm Watch is in effect for…
* Indian Pass to Ochlockonee River Florida
A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline,
during the next 36 hours in the indicated locations. For a depiction
of areas at risk, please see the National Weather Service Storm
Surge Watch/Warning Graphic, available at hurricanes.gov. This is a
life-threatening situation. Persons located within these areas
should take all necessary actions to protect life and property from
rising water and the potential for other dangerous conditions.
Promptly follow evacuation and other instructions from local
officials.
A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. A warning is typically issued
36 hours before the anticipated first occurrence of
tropical-storm-force winds, conditions that make outside
preparations difficult or dangerous. Preparations to protect life
and property should be rushed to completion.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.
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
hurricanes.gov.
A Hurricane Watch means that hurricane conditions are possible
within the watch area.
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, in this case within 12 to 24 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
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At 800 AM EDT (1200 UTC), the center of Tropical Storm Sally was
located near latitude 27.3 North, longitude 84.6 West. Sally is
moving toward the west-northwest near 13 mph (20 km/h), and a
west-northwestward or northwestward motion is expected through
Monday. A decrease in forward speed and a turn toward the north-
northwest is forecast on Tuesday. On the forecast track, the center
of Sally will move over the southeastern and eastern Gulf of Mexico
today, move over the north-central Gulf of Mexico tonight and
Monday, and approach the north-central Gulf Coast within the
hurricane warning area late Monday and Tuesday.
Maximum sustained winds are near 50 mph (85 km/h) with higher
gusts. Strengthening is expected over the next couple of days, and
Sally is forecast to become a hurricane on Monday, with some
additional strengthening possible through early Tuesday.
Tropical-storm-force winds extend outward up to 90 miles (150 km)
from the center. A buoy located about 25 miles offshore of Venice,
Florida, has reported sustained winds of 45 mph and a gust to 58 mph
within the past few hours.
The latest minimum central pressure based on data from an Air Force
Reserve reconnaissance aircraft is 996 mb (29.41 inches).
HAZARDS AFFECTING LAND
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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 including Lake
Borgne…7-11 ft
Port Fourchon to Mouth of the Mississippi River…4-7 ft
Ocean Springs to MS/AL Border…4-7 ft
Lake Pontchartrain and Lake Maurepas…4-6 ft
MS/AL Border to AL/FL Border including Mobile Bay…2-4 ft
AL/FL Border to Chassahowitzka 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 expected within the warning area
starting late Monday, with hurricane conditions possible within
the hurricane watch area by early Tuesday. Tropical storm
conditions are possible within the watch area by Monday, and within
the warning area late Monday.
RAINFALL: Tropical Storm Sally is expected to produce additional
rainfall amounts of 1 to 3 inches with isolated amounts of 6 inches
across southern and central Florida through Monday. This rainfall
will produce flash and urban flooding and prolong high flows and
ongoing minor flooding on rivers across Central Florida.
Tropical Storm Sally is expected to produce rainfall amounts of 6 to
12 inches with isolated amounts of 20 inches over portions of the
Central Gulf Coast between the western Florida Panhandle and far
southeast Louisiana from Monday into the middle of the week.
Rainfall of 4 to 8 inches is possible farther inland over portions
of Mississippi and Alabama. Sally is expected to be a slow moving
system resulting in significant flash flooding near the Central Gulf
Coast through the middle of the week. Flash, urban and rapid onset
flooding along small streams, and minor to isolated major flooding
on rivers is likely.
SURF: Swells will 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.
NEXT ADVISORY
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Next complete advisory at 1100 AM EDT.
$$
Forecaster Brown
