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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KTAE 111404
AFDTAE

Area Forecast Discussion
National Weather Service Tallahassee FL
1004 AM EDT Thu Apr 11 2024

...New UPDATE, AVIATION...

.UPDATE...
-- Changed Discussion --
Issued at 943 AM EDT Thu Apr 11 2024

Line of storms is finally exiting the southeastern Big Bend this
morning, which will end the severe threat for the region. However,
the impacts of the heavy rain will continue to be felt across
much of the area for the next several hours as flooding of roads
and low-lying areas continues. This short-term flooding will
gradually subside into the early afternoon, with a transition to
larger streams and rivers over the next several days. Rainfall
totals varied widely across the area with maximum amounts
reaching 10-12 inches from the central Big Bend of Florida into
South Central Georgia.

Forecast has been updated to reflect precipitation trends.
Otherwise, winds are still expected to pick up this afternoon
behind the front, with the Wind Advisory still in place.
-- End Changed Discussion --


&&

.NEAR TERM...
(Today and tonight)
Issued at 448 AM EDT Thu Apr 11 2024

The greatest concern for additional flooding through sunrise will
be on a corridor along and a little south of a  Tallahassee to
Valdosta line. We did a special 06z balloon sounding overnight,
which observed a seasonally extreme Precipitable Water (PW) value
around 2.2 inches. Given such strong southerly flow into a near
stationary boundary that is draped from about Port Saint Joe to
Tallahassee to Valdosta, the heavy flooding rain threat will
continue for a few more hours.

A negatively tilted shortwave is now moving northeast across the
Central Gulf Coast, and this should finally give this slow- moving
corridor of intense rainfall a much-needed nudge to the east.
This will start to lessen the threat of new flooding after
sunrise, but there will be lots of water on the ground to contend
with. See Hydrology section below.

Besides flooding rainfall, the remaining severe threat will mainly
be in the form of damaging wind gusts. SPC mesoanalysis shows that
surface-based instability over the southeast Big Bend region is
very weak, only 100-200 J/kg. Even with a very strong and
favorable shear profile, it will be hard to generate much in the
way of severe weather for the next few hours.

A deep surface low will move from the Mid-South region across
Kentucky today. To its south, strong westerly flow will develop
today. Much of our forecast area will see sustained winds near 25
mph at times this afternoon, with the occasional gust to 40 mph.
Have therefore extended and expanded the Wind Advisory to include
the whole service area until about sunset this evening.

A few light showers may skirt across our Alabama and Georgia
counties this afternoon, driven in part by speed convergence and
perhaps some colder air aloft in the base of the upper trough.

The air mass will dry out more considerably late this afternoon
and this evening. Skies will clear out, and a cool night in the
50s is forecast.

&&

.SHORT TERM...
(Friday through Saturday night)
Issued at 448 AM EDT Thu Apr 11 2024

A surface high pressure center over eastern Texas tonight will
move east to the Florida Panhandle on Saturday night. Winds will
still be gusty on Friday but will diminish more on Saturday as
high pressure approaches.

With the incoming air mass coming from the west, it will be drier
but will not be particularly cool. Daytime high on Friday and
Saturday will be near normal, though the dry air mass will bring
cool nighttime temperatures which will drop into the 40s and 50s
by sunrise on Saturday and Sunday mornings.

&&

.LONG TERM...
(Sunday through Wednesday)
Issued at 448 AM EDT Thu Apr 11 2024

Surface high pressure will move east of Florida on Sunday,
arriving out near Bermuda on Monday. A surface ridge axis will
extend back westward into northeast Florida. Our low-level flow
will become weakly southeasterly and southerly, allowing the air
mass to start to warming and moistening trend on Sunday. The
warming trend will be aided by a strong 500 mb high over the
southwest Gulf, which will extend a building ridge toward the
northeast Gulf on Tuesday and Wednesday.

Under the influence of high pressure at the surface and aloft, the
forecast will remain rain-free.

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 943 AM EDT Thu Apr 11 2024

Condition are improving at all terminals this morning as the rain
exits to the east, with VFR conditions moving in from west to
east. Winds will be elevated through the remainder of the day
however, with gusts over 20kt.
-- End Changed Discussion --

&&

.MARINE...
Issued at 448 AM EDT Thu Apr 11 2024

Strong low pressure will move by north of the waters today,
leading to a shift to strong and near-gale westerlies. Winds will
start a slow decreasing trend tonight. Surface high pressure will
approach from the west on Saturday, then pass across the waters on
Saturday night. High pressure will move east of Florida on Sunday,
though a ridge axis will extend back toward northeast Florida.
This will bring a turn to gentle and moderate southeast breezes on
Sunday and Monday.

&&

.FIRE WEATHER...
Issued at 448 AM EDT Thu Apr 11 2024

Many of our districts picked up extremely heavy rainfall last
night and early this morning. The heavy rain band will exit east
of the Suwannee River around mid-day, leaving a few passing light
showers over Alabama and Georgia districts this afternoon. West
winds will become quite gusty this afternoon, leading to high
dispersion. By Friday, a drier air mass will be more fully in
place. The continuation of gusty winds will bring one more day of
high dispersion. Surface high pressure will approach the region
and Saturday and pass overhead on Saturday night. Dry air will
continue, but winds will settle down.

&&

.HYDROLOGY...
Issued at 448 AM EDT Thu Apr 11 2024

An impressive heavy rainfall and flash flooding event unfolded
overnight and is still underway. The heaviest new rainfall through
mid-morning will be from near Crawfordville to Madison to Lake
Park. Many locations across the region have picked up 4 to 6 inches
of rain, with heavier stripes of rain in the 7-9 inch range. One
of those heavier stripes impacted Tallahassee overnight,
prompting a rare Flash Flood Emergency.

The slow-moving band of heavy rain will start moving more quickly
off to the east around 7-9 am, so the threat of new flooding rain
will start to diminish after that.

Nonetheless, we are now left with a lot of water on the ground to
fill up our rivers and creeks. The first river Flood Warnings went
out on Wednesday evening for the Shoal River, Pea River,
Choctawhatchee River in Alabama, and the Apalachicola. We are
certainly going to add to this list today as we more fully assess
which river basins got the most rain. Based on where rain fell
overnight, we will need to look most closely at Spring Creek,
Chipola River, the Ochlockonee, Sopchoppy, Aucilla, the Florida
reach of the Choctawhatchee, and the Withlacoochee. Of course,
small creeks and streams will run outside their banks through this
morning.

Thankfully, no hydrologically significant rain is expected beyond
this morning through the next 7 days, but we will have plenty of
water to watch route downstream in that time.

Saltwater... We are now in the high tide cycle of concern along
the upper end of Apalachee Bay. So far, Spring Creek Boat Ramp in
Wakulla County is observing minor coastal flooding, and others are
rising through action stage. Based on current trends, it is
unlikely that we will see any tide gages hit criteria for moderate
coastal flooding, but we will leave the Coastal Flood Warning in
place until after this high tide cycle has passed. This afternoon,
coastal flooding concern will shift over along the Taylor/Dixie
coast, as strong west winds kick in and provide the stronger
onshore push over there. The afternoon high tide cycle will peak
over the northern Nature Coast around 3-4 pm EDT.

&&

.SPOTTER INFORMATION STATEMENT...

-- Changed Discussion --
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Tallahassee   79  54  76  49 /  10  10   0   0
Panama City   74  57  74  53 /   0   0   0   0
Dothan        75  51  73  48 /  10   0   0   0
Albany        78  52  72  48 /  20  10   0   0
Valdosta      81  54  75  49 /  80  10   0   0
Cross City    77  54  75  48 /  90   0   0   0
Apalachicola  73  58  72  54 /  10   0   0   0
-- End Changed Discussion --

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
FL...Wind Advisory until 8 PM EDT /7 PM CDT/ this evening for
     FLZ007>019-026>029-034-108-112-114-115-118-127-128-134.

     Flood Watch until 2 PM EDT this afternoon for FLZ019-028-128.

     High Rip Current Risk through late Friday night for FLZ108-112-
     114-115.

     High Surf Advisory until 11 PM CDT this evening for FLZ108.

     High Surf Advisory until 6 AM EDT /5 AM CDT/ Friday for FLZ112-
     114.

     Coastal Flood Advisory until 8 PM EDT this evening for FLZ115.

     High Surf Advisory until 4 PM EDT this afternoon for FLZ115.

     Coastal Flood Warning until 8 PM EDT this evening for FLZ118-127-
     128-134.

GA...Wind Advisory until 8 PM EDT this evening for GAZ120>131-142>148-
     155>161.

     Flood Watch until 2 PM EDT this afternoon for GAZ159-160.

AL...Wind Advisory until 7 PM CDT this evening for ALZ065>069.

GM...Gale Warning until 3 PM EDT this afternoon for GMZ730-765.

     Gale Warning until 5 PM CDT this afternoon for GMZ750-770.

     Gale Warning until 11 AM EDT /10 AM CDT/ this morning for GMZ752-
     755-772-775.
-- End Changed Discussion --

&&

$$

NEAR TERM...Haner
SHORT TERM...Haner
LONG TERM....Haner
AVIATION...Camp
MARINE...Haner
FIRE WEATHER...Haner
HYDROLOGY...Haner