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Do we have enough going on?

Oof. That 8" light brown is right over me.

Me too! I've got to say, I've lived in this area for 32 years now and have never seen flooding on a catastrophic scale. Just gonna keep my fingers crossed that the trend continues.

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Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 AM EDT Mon Sep 14 2020
 
Day 3
Valid 12Z Wed Sep 16 2020 - 12Z Thu Sep 17 2020 

  • THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS THE WESTERN FLORIDA PANHANDLE AND EXTENDING ACROSS CENTRAL ALABAMA... 

Central Gulf Coast to the Southern Appalachians...
After Tropical Cyclone Sally makes landfall across the central Gulf Coast Wednesday morning, the storm should gradually start to gain forward speed as it makes a rather abrupt turn to the northeast across Alabama.  Very heavy rainfall will continue to remain a problem during the Day 3 period, especially during the 12Z Wednesday to 00Z Thursday time period.  The majority of the rain is expected to fall to the east of the center's track, and this results in a likely swath of 4 to 8 inch rainfall totals, with isolated 12 inch totals, extending from extreme southeast Mississippi to central Alabama.  The latest QPF from WPC is an eastward adjustment owing to changes in the official NHC track, and also follows the eastward adjustment seen in the 00Z model guidance suite.   

There remains a fair amount of model spread regarding the main QPF axis, with the GEFS mean on the northwest side of the guidance, and the NAM well to the southeast and keeping the storm just inland from the coast.  Although the UKMET is displaced to the east regarding the track, its overall depiction of the QPF swath appears reasonable, with portions of the southern Appalachians potentially receiving heavy rain by the end of the Day 3 period.  To account for this, the Slight Risk area was extended to extreme southwest North Carolina, and the Moderate Risk extending from Mobile to near Anniston, Alabama.  Future revisions to these risk areas are likely over the next couple of days as the models are able to better resolve the differences in placement.

 

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Monday, 11 am update

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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


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

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 throughTuesday over coastal areas of the Florida Panhandle, Mississippi,
Alabama, and extreme southeastern Louisiana.

SURF:  Swells from Sally will continue to affect areas from thewest coast of the Florida peninsula westward through the coast of
southeastern Louisiana during the next couple of days. These swellsare likely to cause life-threatening surf and rip current conditions.  Please consult products from your local weather office.

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UPDATE

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Hurricane Sally Tropical Cyclone Update
NWS National Hurricane Center Miami FL       AL192020
1100 AM CDT Mon Sep 14 2020

  • ...NOAA HURRICANE HUNTERS FIND THAT SALLY HAS RAPIDLY STRENGTHENED TO A HURRICANE...

Data from a NOAA Hurricane Hunter aircraft investigating Sally indicate the system has rapidly strengthened to a hurricane, with maximum sustained winds of around 85 mph (140 km/h) with higher gusts. The estimated minimum central pressure is 985 mb (29.09 inches).  

A Special Advisory will be issued shortly to update the intensity forecast for Sally. 


SUMMARY OF 1100 AM CDT...1600 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.6N 86.9W
ABOUT 135 MI...220 KM ESE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 175 MI...280 KM SE OF BILOXI MISSISSIPPI
MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...985 MB...29.09 INCHES

 

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Hurricane Sally Special Discussion Number  13
NWS National Hurricane Center Miami FL       AL192020
1130 AM CDT Mon Sep 14 2020

A NOAA Hurricane Hunter aircraft investigating Sally recently
measured peak flight-level winds of 88 kt at 700 mb and SFMR winds
of 78 kt north of the center, and an Air Force reconnaissance
aircraft just measured 79 kt flight-level winds at 700 mb.  These
data indicate that Sally has rapidly strengthened into a hurricane
with an intensity of around 80 kt. In addition, data from the KEVX
WSR-88D show an eye forming at around 16,000 ft altitude. This
special advisory has been issued to increase the initial and
forecast intensity. Additional adjustments to the intensity forecast
could be required this afternoon.
 Only a slight adjustment was made
to the 12-h track forecast position based on the more northward and 
eastward initial position.

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  14/1630Z 28.7N  87.0W   80 KT  90 MPH
 12H  15/0000Z 28.8N  87.8W   85 KT 100 MPH
 24H  15/1200Z 29.2N  88.8W   90 KT 105 MPH
 36H  16/0000Z 29.8N  89.1W   90 KT 105 MPH

 48H  16/1200Z 30.8N  88.7W   65 KT  75 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

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Mesoscale Precipitation Discussion 0755
NWS Weather Prediction Center College Park MD
1238 PM EDT Mon Sep 14 2020

Areas affected...Eastern Florida Panhandle

Concerning...Heavy rainfall...Flash flooding possible

Valid 141547Z - 142030Z

Summary... A narrow outer band of Sally will continue to spread inland over eastern portions of the Florida Panhandle from Apalachee Bay through the afternoon making for a heavy rainfall and localized flash flooding threat.

Discussion... Three inches of rain have been estimated in northern Franklin as well as southern Liberty and Calhoun counties on the FL Panhandle from KTLH from a persistent outer band of Sally spreading in from the Apalachee Bay. This band is drifting north with southern Wakulla county now experiencing heavy rain. Ample
moisture is spreading in with the band with 2.3" PWs (about 2.5 standard deviations above normal) confirmed by GPS sensors. There is an instability gradient along the shore with about 2500 J/kg SBCAPE over the Apalachee Bay and 1500 J/kg over much of the FL Panhandle which is contributing to diminishing rain rates as the
band shifts inland.

Rainfall of generally 1.5"/hr, but up to 2"/hr have been estimated by KTLH and given the slow northward advancement, local areas have received just about 3" which can be expected to continue going forward this afternoon. Flash flood guidance is generally 3 to 4" in 3 hours, so local exceedance of these guidance values is
possible through the rest of the afternoon as the band continues to re-form and spread inland before slowing diminishing farther inland (by about Washington and Jackson Co). Given the trajectory and inflow from Apalachee Bay this band looks to remain south of I-10 through the afternoon, but is expected to get into at least
southern portions of the Tallahassee metro where drainage issues are anticipated.

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