BULLETIN
Hurricane Sally Intermediate Advisory Number 16A
NWS National Hurricane Center Miami FL AL192020
700 AM CDT Tue Sep 15 2020
...HISTORIC FLOODING IS POSSIBLE FROM SALLY WITH EXTREME LIFE-
THREATENING FLASH FLOODING LIKELY THROUGH WEDNESDAY ALONG PORTIONS
OF THE NORTHERN GULF COAST...
SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...29.1N 88.0W
ABOUT 65 MI...110 KM E OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 105 MI...170 KM SSE OF BILOXI MISSISSIPPI
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...982 MB...29.00 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
None
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* Mouth of the Mississippi River to the Okaloosa/Walton County Line
Florida
* Mobile Bay
A Hurricane Warning is in effect for...
* East of the Mouth of the Pearl River to Navarre Florida
A Tropical Storm Warning is in effect for...
* East of Navarre Florida to Indian Pass Florida
* Mouth of the Pearl River westward to Grand Isle Louisiana,
including Lake Pontchartrain and Lake Maurepas and metropolitan
New Orleans
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.
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 Hurricane Sally was located
near latitude 29.1 North, longitude 88.0 West. Sally is moving
toward the northwest near 2 mph (4 km/h), and this general motion is
expected to continue this morning. A northward turn is expected this
afternoon, followed by a slow north-northeastward to northeastward
motion tonight and continuing through Wednesday night. On the
forecast track, the center of Sally will pass near the coast of
southeastern Louisiana today, and make landfall in the hurricane
warning area tonight or Wednesday morning.
Maximum sustained winds are near 85 mph (140 km/h) with higher
gusts. Although little change in strength is forecast until
landfall occurs, Sally is still expected to be a dangerous hurricane
when it moves onshore along the north-central Gulf coast.
Hurricane-force winds extend outward up to 45 miles (75 km) from
the center and tropical-storm-force winds extend outward up to 125
miles (205 km).
The estimated minimum central pressure based on data from the Air
Force Hurricane Hunter aircraft is 982 mb (29.00 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 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...
Ocean Springs, MS to Dauphin Island, AL including Mobile Bay...6-9
ft
Mouth of the Mississippi River to Ocean Springs, MS including Lake
Borgne...4-7 ft
Dauphin Island, AL to AL/FL Border...4-7 ft
AL/FL Border to Okaloosa/Walton County Line, FL including Pensacola
Bay and Choctawhatchee Bay...2-4 ft
Lake Pontchartrain and Lake Maurepas...2-4 ft
Port Fourchon, LA to Mouth of the Mississippi River...1-3 ft
Okaloosa/Walton County Line to Chassahowitzka, FL including Saint
Andrew Bay...1-3 ft
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
office.
WIND: Hurricane conditions are expected to begin within the
hurricane warning area this late afternoon or tonight. Tropical
storm conditions are occurring in portions of the warning area
across the western Florida Panhandle and Alabama, and these
conditions will gradually spread westward this morning and continue
into Wednesday.
RAINFALL: Sally is expected to be a slow moving system as it
approaches land producing 10 to 20 inches of rainfall with isolated
amounts of 30 inches along and just inland of the central Gulf Coast
from the western Florida Panhandle to far southeastern Mississippi.
Historic flooding is possible with extreme life-threatening flash
flooding likely through Wednesday. In addition, this rainfall will
lead to widespread moderate to major flooding on area rivers.
Sally is forecast to move inland early Wednesday and move
across the Southeast producing rainfall of 4 to 8 inches, with
isolated maximum amounts of 12 inches, across portions of
southeastern Mississippi, southern and central Alabama, northern
Georgia, and the western Carolinas. Significant flash and urban
flooding is likely, as well as widespread minor to moderate
flooding on some rivers.
TORNADOES: A tornado or two will be possible this morning in
coastal areas of the Florida Panhandle and Alabama. The tornado
threat should increase and slowly spread inland the rest of today
into Wednesday.
SURF: Swells from Sally will continue to affect the coast from the
Florida Big Bend westward to 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.
NEXT ADVISORY
-------------
Next complete advisory at 1000 AM CDT.
$$
Forecaster Brown
BULLETIN
Hurricane Sally Advisory Number 17
NWS National Hurricane Center Miami FL AL192020
1000 AM CDT Tue Sep 15 2020
...SALLY CRAWLING NORTHWESTWARD TOWARD THE NORTHERN GULF COAST...
...HISTORIC FLOODING IS POSSIBLE FROM SALLY WITH EXTREME LIFE-
THREATENING FLASH FLOODING LIKELY THROUGH WEDNESDAY ALONG PORTIONS
OF THE NORTHERN GULF COAST...
SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...29.1N 88.2W
ABOUT 55 MI...85 KM E OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 110 MI...180 KM S OF MOBILE ALABAMA
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...983 MB...29.03 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
The Hurricane Warning from the Mouth of the Pearl River to Bay St.
Louis Mississippi has been changed to a Tropical Storm Warning.
The Tropical Storm Warning for Lake Pontchartrain, Lake Maurepas,
and metropolitan New Orleans has been discontinued.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* Mouth of the Mississippi River to the Okaloosa/Walton County Line
Florida
* Mobile Bay
A Hurricane Warning is in effect for...
* East of Bay St. Louis to Navarre Florida
A Tropical Storm Warning is in effect for...
* East of Navarre Florida to Indian Pass Florida
* Bay St. Louis westward to Grand Isle Louisiana
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.
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 1000 AM CDT (1500 UTC), the center of Hurricane Sally was located
near latitude 29.1 North, longitude 88.2 West. Sally is moving
toward the northwest near 2 mph (4 km/h). A slow north-
northwestward to northward motion is expected this afternoon,
followed by a slow northward to north-northeastward motion tonight
through Wednesday night. On the forecast track, the center of Sally
will pass near the coast of southeastern Louisiana today, and make
landfall in the hurricane warning area late tonight or Wednesday.
Maximum sustained winds are near 85 mph (140 km/h) with higher
gusts. Although little change in strength is forecast until
landfall occurs, Sally is still expected to be a dangerous hurricane
when it moves onshore along the north-central Gulf coast.
Hurricane-force winds extend outward up to 45 miles (75 km) from the
center and tropical-storm-force winds extend outward up to 125 miles
(205 km).
The latest minimum central pressure reported by a NOAA Hurricane
Hunter aircraft is 983 mb (29.03 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 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...
MS/AL Border to AL/FL Border including Mobile Bay...4-7 ft
Mouth of the Mississippi River to Mouth of the Pearl River including
Lake Borgne...4-6 ft
Mouth of the Pearl River to MS/AL Border...3-5 ft
AL/FL Border to Okaloosa/Walton County Line, FL including Pensacola
Bay and Choctawhatchee Bay...3-5 ft
Lake Pontchartrain and Lake Maurepas...2-4 ft
Okaloosa/Walton County Line,FL to Chassahowitzka, FL including Saint
Andrews Bay...1-3 ft
Grand Isle, LA to Mouth of the Mississippi River...1-3 ft
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
office.
WIND: Hurricane conditions are expected to begin within the
hurricane warning area later today or tonight. Tropical
storm conditions are already occurring in portions of the warning
areas, and these conditions will continue through Wednesday night.
RAINFALL: Sally is forecast to produce 10 to 20 inches of rainfall
with isolated amounts of 30 inches along and just inland of the
central Gulf Coast from the western Florida Panhandle to far
southeastern Mississippi. Historic flooding is likely with extreme
life-threatening flash flooding likely through Wednesday. In
addition, this rainfall will lead to widespread moderate to major
flooding on area rivers.
Sally is forecast to move inland Wednesday and track across the
Southeast producing rainfall of 4 to 8 inches, with isolated maximum
amounts of 12 inches, across portions of southeastern Mississippi,
southern and central Alabama, northern Georgia, and the western
Carolinas. Significant flash and urban flooding is likely, as well
as widespread minor to moderate flooding on some rivers.
TORNADOES: Isolated tornadoes may occur today through Wednesday
across portions of the Florida Panhandle and southern Alabama.
SURF: Swells from Sally will continue to affect the coast from the
Florida Big Bend westward to 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.
NEXT ADVISORY
-------------
Next intermediate advisory at 100 PM CDT.
Next complete advisory at 400 PM CDT.
$$
Forecaster Brown
Hurricane Sally Discussion Number 17
NWS National Hurricane Center Miami FL AL192020
1000 AM CDT Tue Sep 15 2020
The satellite presentation of Sally has not changed much since
overnight. A ragged eye is seen in WSR-88D radar imagery, with
a band occasionally trying to wrap around the southwestern side.
A NOAA reconnaissance aircraft has just recently provided a new
center fix, and data from the center drop indicated the minimum
pressure is 983 mb. The first pass through the northeastern
quadrant suggests that the 50-kt wind field may have expanded, but
there has been little change in peak winds reported by the
aircraft. The intensity has been held at 75 kt pending additional
data from the NOAA P-3 mission that has just begun. A highly
elevated oil rig just northeast of the center reported peak has
reported sustained winds of 69 kt with a gust to 86 kt around 1200
UTC this morning.
Sally has been meandering this morning, but the longer-term motion
is northwestward or 315/2 kt. Sally remains within an area of weak
steering flow, but a weak mid-level trough over the south-central
United States is forecast to slide eastward over the next over the
next couple of days. This pattern should cause Sally to move very
slowly north-northwestward to northward over the next 24 hours, with
the center of the hurricane nearing the northern Gulf Coast late
tonight or Wednesday. By late Wednesday, Sally should turn
northeastward as the aforementioned trough approaches Missouri and
Arkansas. The new forecast has been nudged slightly eastward in
the early portion of the track forecast, but the latter portion is
very close to the previous advisory. The new track lies a little
to the west of the various consensus aids in deference to the
typically reliable GFS and ECMWF models that are near the left
edge of the guidance envelope. Sally's forward motion is forecast
to be around 5 kt or less throughout the forecast period, which
will result in a long period of heavy rainfall and historic flooding
along the north-central Gulf Coast.
Moderate westerly shear and upwelling beneath the slow moving
hurricane are likely to prevent strengthening today. The shear is
forecast to increase tonight and although some slight weakening
could occur before the center reaches the coast, Sally is predicted
to remain a dangerous hurricane through landfall. Once Sally moves
inland, rapid weakening is expected and circulation is forecast to
lose definition and dissipate by day 4.
Users are reminded to not focus on the specific timing and location
of landfall. Life-threatening storm surge, historic flash flooding
from heavy rainfall, and dangerous winds will affect a large portion
of the north-central Gulf Coast during the next few days.
KEY MESSAGES:
1. Life-threatening storm surge is expected from the Mouth of the
Mississippi River to the Okaloosa/Walton County Line in the Florida
Panhandle. The highest inundation is expected along the Alabama
coast, including Mobile Bay.
2. Historic life-threatening flash flooding is likely through
Wednesday along and just inland of the coast from the western
Florida Panhandle to far southeastern Mississippi. Widespread
moderate to major river flooding is forecast along and just inland
of the central Gulf Coast. Significant flash and urban flooding, as
well as widespread minor to moderate river flooding, are likely
across inland portions of Mississippi, Alabama, northern Georgia,
and the western Carolinas through the week.
3. Hurricane conditions are expected today within portions of the
Hurricane Warning area along the Mississippi and Alabama coastlines
and the western Florida Panhandle.
FORECAST POSITIONS AND MAX WINDS
INIT 15/1500Z 29.1N 88.2W 75 KT 85 MPH
12H 16/0000Z 29.6N 88.2W 75 KT 85 MPH
24H 16/1200Z 30.2N 88.1W 70 KT 80 MPH
36H 17/0000Z 31.0N 87.6W 55 KT 65 MPH...INLAND
48H 17/1200Z 31.9N 86.6W 35 KT 40 MPH...INLAND
60H 18/0000Z 32.6N 85.2W 25 KT 30 MPH...INLAND
72H 18/1200Z 33.0N 83.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 19/1200Z...DISSIPATED
$$
Forecaster Brown
BULLETIN
Hurricane Sally Intermediate Advisory Number 17A
NWS National Hurricane Center Miami FL AL192020
100 PM CDT Tue Sep 15 2020
...SALLY INCHING ITS WAY TOWARD THE NORTHERN GULF COAST...
...HISTORIC LIFE-THREATENING FLOODING LIKELY ALONG PORTIONS
OF THE NORTHERN GULF COAST...
SUMMARY OF 100 PM CDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...29.2N 88.2W
ABOUT 60 MI...95 KM E OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 105 MI...165 KM S OF MOBILE ALABAMA
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...982 MB...29.00 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
None
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* Mouth of the Mississippi River to the Okaloosa/Walton County Line
Florida
* Mobile Bay
A Hurricane Warning is in effect for...
* East of Bay St. Louis to Navarre Florida
A Tropical Storm Warning is in effect for...
* East of Navarre Florida to Indian Pass Florida
* Bay St. Louis westward to Grand Isle Louisiana
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.
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 100 PM CDT (1800 UTC), the center of Hurricane Sally was located
near latitude 29.2 North, longitude 88.2 West. Sally is moving
toward the northwest near 2 mph (4 km/h). A slow north-
northwestward to northward motion is expected this afternoon,
followed by a slow northward to north-northeastward motion tonight
through Wednesday night. On the forecast track, the center of Sally
will pass near the coast of southeastern Louisiana today, and make
landfall in the hurricane warning area late tonight or Wednesday.
Maximum sustained winds are near 80 mph (130 km/h) with higher
gusts. Although little change in strength is forecast until
landfall occurs, Sally is still expected to be a dangerous hurricane
when it moves onshore along the north-central Gulf coast.
Hurricane-force winds extend outward up to 45 miles (75 km) from
the center and tropical-storm-force winds extend outward up to 125
miles (205 km). A NOAA buoy located about 50 miles (80 km)
southeast of Mobile, Alabama, recently reported sustained winds of
56 mph (90 km/h) and a gust to 67 mph (108 km/h) within the past few
hours. A weather station at Dauphin Island, Alabama, recently
reported sustained winds of 45 mph (72 km/h) and a gust to 59 mph
(95 km/h).
The latest minimum central pressure reported by a NOAA Hurricane
Hunter aircraft is 982 mb (29.00 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 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...
MS/AL Border to AL/FL Border including Mobile Bay...4-7 ft
Mouth of the Mississippi River to Mouth of the Pearl River including
Lake Borgne...4-6 ft
Mouth of the Pearl River to MS/AL Border...3-5 ft
AL/FL Border to Okaloosa/Walton County Line, FL including Pensacola
Bay and Choctawhatchee Bay...3-5 ft
Lake Pontchartrain and Lake Maurepas...2-4 ft
Okaloosa/Walton County Line,FL to Chassahowitzka, FL including Saint
Andrews Bay...1-3 ft
Grand Isle, LA to Mouth of the Mississippi River...1-3 ft
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
office.
WIND: Hurricane conditions are expected to begin within the
hurricane warning area later today or tonight. Tropical storm
conditions are already occurring in portions of the warning areas,
and these conditions will continue through Wednesday night.
RAINFALL: Sally is forecast to produce 10 to 20 inches of rainfall
with isolated amounts of 30 inches along and just inland of the
central Gulf Coast from the western Florida Panhandle to far
southeastern Mississippi. Historic flooding is likely with extreme
life-threatening flash flooding likely through Wednesday. In
addition, this rainfall will lead to widespread moderate to major
flooding on area rivers.
Sally is forecast to move inland Wednesday and track across the
Southeast producing rainfall of 4 to 8 inches, with isolated maximum
amounts of 12 inches, across portions of southeastern Mississippi,
southern and central Alabama, northern Georgia, and the western
Carolinas. Significant flash and urban flooding is likely, as well
as widespread minor to moderate flooding on some rivers.
TORNADOES: Isolated tornadoes may occur today through Wednesday
across portions of the Florida Panhandle and southern Alabama.
SURF: Swells from Sally will continue to affect the coast from the
Florida Big Bend westward to 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.
NEXT ADVISORY
-------------
Next complete advisory at 400 PM CDT.
$$
Forecaster Brown
BULLETIN
Hurricane Sally Advisory Number 18
NWS National Hurricane Center Miami FL AL192020
400 PM CDT Tue Sep 15 2020
...TROPICAL-STORM-FORCE WINDS SPREADING ONSHORE ALONG THE
NORTH-CENTRAL GULF COAST...
...HISTORIC LIFE-THREATENING FLOODING LIKELY ALONG PORTIONS
OF THE NORTHERN GULF COAST...
SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...29.5N 88.1W
ABOUT 85 MI...135 KM S OF MOBILE ALABAMA
ABOUT 90 MI...140 KM SW OF PENSACOLA FLORIDA
MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H
PRESENT MOVEMENT...N OR 350 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
None
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Warning is in effect for...
* Mouth of the Mississippi River to the Okaloosa/Walton County Line
Florida
* Mobile Bay
A Hurricane Warning is in effect for...
* East of Bay St. Louis to Navarre Florida
A Tropical Storm Warning is in effect for...
* East of Navarre Florida to Indian Pass Florida
* Bay St. Louis westward to Grand Isle Louisiana
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.
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 400 PM CDT (2100 UTC), the center of Hurricane Sally was located
near latitude 29.5 North, longitude 88.1 West. Sally is moving
toward the north near 2 mph (4 km/h). A slow northward motion is
expected tonight, followed by a slow north-northeastward to
northeastward motion on Wednesday and Wednesday night. A slightly
faster northeastward motion is expected on Thursday. On the
forecast track, the center of Sally will approach the northern Gulf
Coast tonight, and make landfall in the hurricane warning area
late tonight or Wednesday. Sally is expected to move inland across
southeastern Alabama Wednesday night and Thursday.
Data from a NOAA Hurricane Hunter aircraft and NWS Doppler radar
indicates that maximum sustained winds are near 80 mph (130 km/h)
with higher gusts. Little change in strength is forecast until
landfall occurs and Sally is expected to be a dangerous hurricane
when it moves onshore along the north-central Gulf Coast.
Hurricane-force winds extend outward up to 40 miles (65 km) from the
center and tropical-storm-force winds extend outward up to 125 miles
(205 km). A NOAA buoy located about 50 miles (80 km) southeast of
Mobile, Alabama, recently reported sustained winds of 58 mph (94
km/h) and a gust to 67 mph (108 km/h) within the past couple of
hours. An observing site at the Okaloosa Fishing Pier in Florida
has reported sustained winds of 44 mph (70 km/h) and a gust to 52
mph (83 km/h).
The latest minimum central pressure estimated from reconnaissance
aircraft data is 979 mb (28.91 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 RAINFALL: Sally is forecast to produce 10 to 20 inches of rainfall
with isolated amounts of 30 inches along and just inland of the
central Gulf Coast from the Florida Panhandle west of the
Apalachicola River to far southeastern Mississippi. Historic
life-threatening flash flooding is likely. In addition, this
rainfall will lead to widespread moderate to major flooding on area
rivers.
Sally is forecast to turn inland Wednesday and track across the
Southeast producing rainfall of 4 to 8 inches, with isolated maximum
amounts of 12 inches, across portions of southeastern Mississippi,
southern and central Alabama, central and northern Georgia, and the
western Carolinas. Significant flash and urban flooding is likely,
as well as widespread minor to moderate flooding on some rivers.
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...
Dauphin Island, AL to AL/FL Border including Mobile Bay...4-6 ft
Mouth of the Mississippi River to Mouth of the Pearl River including
Lake Borgne...3-5 ft
MS/AL Border to Dauphin Island, AL...3-5 ft
AL/FL Border to Okaloosa/Walton County Line, FL including Pensacola
Bay and Choctawhatchee Bay...3-5 ft
Mouth of the Pearl River to MS/AL Border...2-4 ft
Lake Pontchartrain and Lake Maurepas...2-4 ft
Okaloosa/Walton County Line, FL to Chassahowitzka, FL including
Saint Andrews Bay...1-3 ft
Grand Isle, LA to Mouth of the Mississippi River...1-3 ft
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
office.
WIND: Hurricane conditions are expected to begin within the
hurricane warning area this evening. Tropical storm conditions are
already occurring in portions of the warning areas, and will
continue through Wednesday night.
TORNADOES: A few tornadoes may occur this evening through Wednesday
across portions of the Florida Panhandle and southern Alabama.
SURF: Swells from Sally will continue to affect the coast from the
Florida Big Bend westward to 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.
NEXT ADVISORY
-------------
Next intermediate advisory at 700 PM CDT.
Next complete advisory at 1000 PM CDT.
$$
Forecaster Brown
Hurricane Sally Discussion Number 18
NWS National Hurricane Center Miami FL AL192020
400 PM CDT Tue Sep 15 2020
Sally has been inching its way toward the north-central Gulf Coast
today. The overall structure of the storm has remained about the
same during the day with a large ragged eye in apparent in radar
imagery. A NOAA P-3 aircraft that has been sampling the storm
since late this morning has reported peak flight-level winds of
76 kt, and NWS Doppler radar has shown velocities of 75-80 kt at
around 7000 ft. The intensity was reduced to 70 kt on the 1800 UTC
intermediate advisory and remains at that value for this advisory.
Radar and aircraft fixes show that Sally has been moving very slowly
toward the north or 350/2 kt. The track forecast philosophy remains
unchanged from the previous advisory. Sally is currently located
within an area of weak steering flow between a couple of mid-level
ridges to its east and west. A weak mid-level trough over the
south-central United States is forecast to slide eastward over the
next few days, which should cause Sally to turn north-northeastward
and then northeastward over the next 24-36 hours. Sally's forward
speed is expected to remain quite slow over the next 24-48 hours,
but the guidance has trended slightly faster after that time. The
slow forward speed is likely to result in a historical rainfall
event for the north-central Gulf Coast. It may sound like a broken
record, but the track guidance has again shifted eastward during the
first 24-36 hours, and the NHC forecast has been adjusted
accordingly. Since Sally has a large wind field, and storm surge
and rainfall hazards extend far from the eye, users should not focus
on the exact forecast track or specific location and timing of
landfall as strong winds and bands of heavy rainfall are already
affecting the Gulf Coast and will continue to do so for quite some
time.
The combination of upwelling and moderate westerly shear is likely
to result in little change in strength prior to Sally moving
onshore. Once the center of the hurricane moves onshore, rapid
weakening is expected and the global models indicate that the
circulation will becoming elongated along a frontal boundary in 3
to 4 days.
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 far southeastern
Mississippi. Widespread moderate to major river flooding is
forecast along and just inland of the central Gulf Coast.
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 15/2100Z 29.5N 88.1W 70 KT 80 MPH
12H 16/0600Z 29.9N 88.1W 70 KT 80 MPH
24H 16/1800Z 30.6N 87.7W 60 KT 70 MPH...INLAND
36H 17/0600Z 31.5N 86.9W 40 KT 45 MPH...INLAND
48H 17/1800Z 32.5N 85.3W 30 KT 35 MPH...INLAND
60H 18/0600Z 33.1N 83.3W 25 KT 30 MPH...INLAND
72H 18/1800Z 33.5N 81.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 19/1800Z...DISSIPATED
$$
Forecaster Brown