Tropical Storm Sally Public Advisory
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000
WTNT34 KNHC 141451
TCPAT4
BULLETIN
Tropical Storm Sally Advisory Number 12
NWS National Hurricane Center Miami FL AL192020
1000 AM CDT Mon Sep 14 2020
...SALLY EXPECTED TO BECOME A HURRICANE LATER TODAY OR TONIGHT...
...HURRICANE WARNING ISSUED FOR THE COAST OF ALABAMA...
SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.4N 86.9W
ABOUT 140 MI...230 KM ESE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 185 MI...295 KM SE OF BILOXI MISSISSIPPI
MAXIMUM SUSTAINED WINDS...
65 MPH...100 KM/H
PRESENT MOVEMENT..
.WNW OR 285 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...991 MB...29.27 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
The Tropical Storm Warning and Hurricane Watch from the
Mississippi/Alabama Border to the Alabama/Florida Border has been
changed to a Hurricane Warning.
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 Alabama/Florida Border
* Lake Pontchartrain and Lake Maurepas including metropolitan New
Orleans
A Tropical Storm Warning is in effect for...
* Alabama/Florida Border to Indian Pass Florida
* Intracoastal City Louisiana to west of Morgan City
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 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
----------------------
Data from an Air Force Reserve Hurricane Hunter aircraft indicate
that the center of Sally has reformed to the east of the previous
estimated location. At 1000 AM CDT (1500 UTC), the center of
Tropical Storm Sally was located near latitude 28.4 North,
longitude 86.9 West. Sally is moving toward the west-northwest near
6 mph (9 km/h). This general motion is expected to continue today,
followed by a decrease in forward speed and a turn toward 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 tonight, and
make landfall in the hurricane warning area on Tuesday or Tuesday
night. Afterward, Sally is expected to move slowly north-
northeastward near the northern Gulf Coast through Wednesday.
Maximum sustained winds are 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.
The latest minimum central pressure estimated from reconnaissance
aircraft data is 991 mb (29.27 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...
Mouth of the Mississippi River to Ocean Springs, MS including Lake
Borgne...7-11 ft
Ocean Springs, MS to MS/AL Border...5-8 ft
MS/AL Border to AL/FL Border including Mobile Bay...4-7 ft
Lake Pontchartrain and Lake Maurepas...4-6 ft
Port Fourchon, LA to Mouth of the Mississippi River...3-5 ft
AL/FL Border to Chassahowitzka, FL including Pensacola Bay,
Choctawhatchee Bay, and Saint Andrew Bay...1-3 ft
Burns Point, LA to Port Fourchon, LA...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
office.
WIND: Hurricane conditions are expected to begin within the
hurricane warning area tonight. Tropical storm conditions are
possible within the watch area today, and are expected to begin
within the warning area later today.
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 likely. In
addition, this rainfall will likely lead to widespread minor to
isolated major flooding on area rivers.
Sally is forecast 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 Carolinas Thursday into
Friday. Flash, urban, and minor river flooding is possible across
this region.
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.
NEXT ADVISORY
-------------
Next intermediate advisory at 100 PM CDT.
Next complete advisory at 400 PM CDT.
$$
Forecaster Brown
https://www.nhc.noaa.gov/text/refres...l/141451.shtml
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Tropical Storm Sally Forecast Discussion
Home Public Adv Fcst Adv Discussion Wind Probs Graphics Archive
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ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
Tropical Storm Sally Discussion Number 12
NWS National Hurricane Center Miami FL AL192020
1000 AM CDT Mon Sep 14 2020
An intense burst of deep convection with cloud tops colder than -80
degrees Celsius has developed over and the to east of the center
this morning. A recent fix from an Air Force Reserve Hurricane
Hunter aircraft indicates that the center has reformed to the
east of the previous estimated location, beneath the burst of
deep convection. NWS WSR-88D radar imagery shows an increase in
banding around the eastern and southeastern portion of new center
found by the aircraft and it appears that an eye is in its formative
stage. The aircraft has reported believable SFMR winds of 55 kt, and
that is the basis for the initial intensity. The most recent
minimum pressure estimated from the aircraft data is 991 mb, down
several millibars from the first fix on this flight.
Sally is located within a conducive environment of low wind shear,
warm waters, and a moist atmosphere. These conditions are likely to
lead to steady strengthening over the next 24 hours or so. With the
recent increase in organization of the inner core, there is more
confidence that Sally will strengthen to a hurricane later today or
tonight. Additional strengthening is possible on Tuesday while the
storm moves slowly northwestward near the coast of southeast
Louisiana. Increasing westerly wind shear and land interaction will
probably slow the intensification rate by late tomorrow. The new
NHC intensity forecast is similar to the previous advisory and is
near the upper-end of the guidance envelope. Since Sally is
forecast to be moving very slowly around the time of landfall a
slower rate of weakening is indicated since a large portion of the
circulation will remain over water for some time.
Given the recent re-formation of the center, the initial motion is a
somewhat uncertain west-northwestward at 5 kt. Weak ridging over
the southeastern United State should steer Sally slowly west-
northwestward through tonight. After that time, a northwestward to
northward turn is anticipated but the exact timing and location of
the turn remains uncertain.
The general trend in the guidance has
been eastward for the past few cycles, and the NHC forecast has been
nudged in that direction and lies between the GFS and ECMWF models
but a little west of the various consensus aids.
Regardless of the exact forecast track and intensity of Sally,
the slow-moving storm is expected to cause a life-threatening storm
surge and freshwater flooding event.
KEY MESSAGES:
1. It is too early to determine where Sally's center will move
onshore given the uncertainty in the timing and location of Sally's
northward turn near the central Gulf Coast. Users should not focus
on the details of the official forecast track, since NHC's average
forecast error at 48 hours is around 80 miles, and dangerous storm
surge, rainfall, and wind hazards will extend well away from the
center.
2. An extremely dangerous and life-threatening storm surge is
expected for areas outside the southeastern Louisiana Hurricane and
Storm Damage Risk Reduction System from Port Fourchon, Louisiana, to
the Alabama/Florida border, where a Storm Surge Warning is in
effect. Residents in these areas should follow any advice given by
local officials.
3. Hurricane conditions are expected tonight within the Hurricane
Warning area in southeastern Louisiana and are expected by late
Tuesday within the Hurricane Warning area along the Mississippi and
Alabama coastline. Tropical storm conditions are likely to begin
later today and this evening in these areas and preparations
should be rushed to completion.
4. Life-threatening flash flooding is likely, as well as widespread
minor to isolated major flooding, on area rivers 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 Mississippi and Alabama through the middle of the
week. Flooding impacts are expected to spread farther across the
Southeast through the week. Sally could continue to produce flash
flooding across the Florida peninsula and prolong existing minor
river flooding across west-central Florida through today.
FORECAST POSITIONS AND MAX WINDS
INIT 14/1500Z 28.4N 86.9W 55 KT 65 MPH
12H 15/0000Z 28.7N 88.0W 65 KT 75 MPH
24H 15/1200Z 29.2N 88.8W 75 KT 85 MPH
36H 16/0000Z 29.8N 89.1W 80 KT 90 MPH
48H 16/1200Z 30.8N 88.7W 60 KT 70 MPH...INLAND
60H 17/0000Z 31.8N 87.7W 30 KT 35 MPH...INLAND
72H 17/1200Z 32.6N 86.5W 25 KT 30 MPH...INLAND
96H 18/1200Z 33.1N 84.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 19/1200Z...DISSIPATED
$$
Forecaster Brown
NNNN
https://www.nhc.noaa.gov/text/refres.../141451.shtml?
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