7 A.M. MONDAY: SALLY'S TRACK INCHES EAST; TUESDAY LANDFALL EXPECTED
Tropical Storm Sally Intermediate Advisory Number 11A
NWS National Hurricane Center Miami FL AL192020
700 AM CDT Mon Sep 14 2020
...SALLY A LITTLE STRONGER AS IT MOVES SLOWLY WEST-NORTHWESTWARD
OVER THE NORTH-CENTRAL GULF OF MEXICO...
...LIKELY TO PRODUCE LIFE-THREATENING STORM SURGE, HURRICANE-FORCE
WINDS, AND FLASH FLOODING ALONG PORTIONS OF THE NORTHERN GULF COAST
STARTING LATE TODAY...
SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
ABOUT 115 MI...185 KM ESE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 165 MI...265 KM SE OF BILOXI MISSISSIPPI
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.35 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* Port Fourchon Louisiana to the Alabama/Florida Border
* Lake Pontchartrain, Lake Maurepas, and Lake Borgne
* Mobile Bay
A Hurricane Warning is in effect for...
* Morgan City Louisiana to the Mississippi/Alabama Border
* Lake Pontchartrain and Lake Maurepas including metropolitan New
A Tropical Storm Warning is in effect for...
* Mississippi/Alabama Border to Indian Pass Florida
* Intracoastal City Louisiana to west of Morgan City
A Hurricane Watch is in effect for...
* Mississippi/Alabama Border to the Alabama/Florida Border
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. 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 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.
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 700 AM CDT (1200 UTC), the center of Tropical Storm Sally was located near latitude 28.4 North, longitude 87.4 West. Sally is moving toward the west-northwest near 8 mph (13 km/h). This general motion is expected today, followed by a decrease in forward speed and a turn to the northwest tonight and a northward turn sometime on Tuesday. On the forecast track, the center of Sally will move over the north-central Gulf of Mexico today, approach southeastern
Louisiana this afternoon, and make landfall in the hurricane warning area on Tuesday. Afterward, Sally is expected to move slowly
north-northeastward near the northern Gulf Coast through Wednesday.
Maximum sustained winds have increased to near 65 mph (100 km/h)
with higher gusts. Strengthening is expected over the next day or
so, and Sally is forecast to become a hurricane by tonight, with
additional strengthening possible before the center crosses the
northern Gulf Coast.
Tropical-storm-force winds extend outward up to 125 miles (205 km)
from the center. NOAA buoy 42039, located about 130 miles (215 km)
south-southeast of Pensacola, Florida, recently reported peak
sustained winds of 49 mph (79 km/h) and a gust to 58 mph (94 km/h).
The estimated minimum central pressure is 994 mb (29.35 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,
and on the web at www.hurricanes.gov/text/MIATCDAT4.shtml(link is external)
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
Ocean Springs to MS/AL Border...5-8 ft
MS/AL Border to AL/FL Border including Mobile Bay...4-6 ft
Lake Pontchartrain and Lake Maurepas...4-6 ft
Port Fourchon to Mouth of the Mississippi River...3-5 ft
AL/FL Border to Navarre including Pensacola Bay...2-4 ft
Navarre to Chassahowitzka including Choctawhatchee Bay and Saint
Andrew Bay...1-3 ft
Burns Point to Port Fourchon...1-3 ft
Overtopping of local levees outside of the Hurricane and Storm
Damage Risk Reduction System is possible where local inundation
values may be higher than those shown above.
The deepest water will occur along the immediate coast in areas of
onshore winds, 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
WIND: Hurricane conditions are expected within the hurricane
warning area starting late today. Tropical storm conditions are
possible within the watch area during the next few hours, and are
expected within the warning area beginning this morning.
RAINFALL: Sally is expected to be a slow-moving system as it
approaches land producing 8 to 16 inches of rainfall with isolated
amounts of 24 inches over portions of the central Gulf Coast from
the western Florida Panhandle to far southeast Louisiana through the
middle of the week. Life-threatening flash flooding is possible. In
addition, this rainfall will likely lead to widespread minor to
isolated major flooding on area rivers.
Sally is forecast to move farther inland early Wednesday and track
into the Southeast with rainfall of 6 to 12 inches possible across
portions of inland southeast Mississippi and Alabama. Significant
flash and urban flooding is likely, as well as widespread minor to
moderate flooding on some rivers.
Further heavy rain is then anticipated across portions of eastern
Tennessee, northern Georgia and western North Carolina Thursday into
Friday. Flash, urban, and minor river flooding is possible across
Outer bands of Sally are expected to produce additional rainfall of
1 to 3 inches across the Florida peninsula today. This rainfall may
produce flash and urban flooding and prolong high flows and ongoing
minor flooding on rivers across central Florida.
TORNADOES: A tornado or two may occur this afternoon through
Tuesday over coastal areas of the Florida Panhandle, Mississippi,
Alabama, and extreme southeastern Louisiana.
SURF: Swells from Sally will continue to affect areas from the
west coast of the Florida peninsula westward through the coast of
southeastern Louisiana 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.