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000
FXUS62 KTAE 101054
AFDTAE

Area Forecast Discussion
National Weather Service Tallahassee FL
654 AM EDT Wed Apr 10 2024

...New AVIATION...

.SYNOPSIS...
Issued at 439 AM EDT Wed Apr 10 2024

A multi-hazard high-impact weather event is coming up this
afternoon, peaking tonight, and improving later Thursday. Hazards
will include:

1) Severe thunderstorms... possibly significant over the Panhandle
and Alabama Wiregrass
2) Heavy rain, flash flooding, and river flooding
3) Strong non-convective wind gusts over land
4) Gales over the Gulf waters
5) Minor coastal flooding on shorelines around Apalachee Bay
6) Life-threatening high surf at the beaches

&&

.NEAR TERM...
(Today through Thursday)
Issued at 439 AM EDT Wed Apr 10 2024

Lots of moving parts will make for a somewhat complicated, and busy,
forecast the next 36 hours. First up is the potential for strong to
severe storms as early as this afternoon with a line of showers and
storms moving in from the west; the threat for strong to severe
storms lingers into Thursday morning due to multiple waves of storms
being possible. Flooding is another concern as some of the latest hi-
res guidance has shifted the swath of heavier rain more to the south
over our area. In addition to that, breezy to windy southerly winds
are expected ahead of the showers and storms today with a Wind
Advisory in effect for the coastal areas and western Florida
Panhandle this afternoon into this evening.

Latest satellite and radar analysis this morning shows a weakening
cluster of showers and thunderstorms across central Alabama and
Mississippi. Additional showers and storms stretch back west all the
way into Texas. The line of storms in Texas is rapidly pushing east
and is forecast to race east along the northern Gulf Coast this
morning and into the afternoon. Latest timing has the line of
storms, or mesoscale convective system (MCS), arriving in our
western Florida Panhandle/SE Alabama Counties as early as 1 to 3 PM
CDT. Damaging winds are the primary concern with the MCS with
tornadoes embedded within the line also possible. A discrete storm
ahead of the line may develop and be able to produce damaging wind
gusts or a tornado.

The MCS is forecast to slow down and eventually weaken over our area
as it out runs the 50+kt low-level jet (LLJ). Where it does so will
be important as those on the southern side of the MCS will have the
greatest chance at seeing several inches of rain. There remains a
large degree of uncertainty with respect to where the southern side
of the MCS will be, whether over land or the Gulf. Either way, rain,
and lots of it, is anticipated with this first round.

The second round of potentially strong to severe thunderstorms will
come as the low-level jet (LLJ) re-strengthens over the region ahead
of the cold front and H5 trough later tonight into early Thursday
morning. Forecast hodographs show larger hodographs as 0-1km Storm
Relative Helicity (SRH) increases to 300+ m^2/s^2 along with 40 to
60 knots of bulk shear. Instability is forecast to increase to
around 1500 J/kg south of the decaying MCS and could allow for the
formation of a few supercells to develop ahead of and along the cold
front. Of course, this will largely depend on where the MCS
ultimately goes and stalls, so there remains a large degree of
uncertainty with this portion of the forecast.

Heavy rain is expected, especially if there becomes a stalled
east-west boundary for storms to repeatedly train along. See
Hydrology section below for details.

Strong winds ahead of the showers and thunderstorms are possible
thanks to a tight pressure gradient across the southeast and a
strengthening LLJ. A Wind Advisory has been issued along the
immediate coast and just inland to account for the potential of
gusts up to 40, maybe 45, mph this afternoon into the evening
ahead of the showers and storms.

Along the immediate coast, there remains a High Risk of Rip Currents
along our beaches today along with a High Surf Advisory this
evening/tonight for surf heights of 6 to 9 feet. Additionally, a
Coastal Flood Advisory was considered. However, timing of the surge
from this storm system is not expected to line up with high tide at
this time. We`ll continue to monitor the coastal flood threat
throughout the day.

Drier conditions take over Thursday following the front as moderate
to breezy west to northwest winds take over.

Temperatures today range from the upper 70s in the western Florida
Panhandle and southeastern Alabama to the lower 80s across the Big
Bend of Florida. Lows tonight only manage to cool into the middle
60s as we remain ahead of the cold front.

&&

.SHORT TERM...
(Thursday Night through Saturday)
Issued at 439 AM EDT Wed Apr 10 2024

Following Thursdays cold frontal passage, surface high pressure
will move from Texas on Thursday night to the Florida Panhandle on
Saturday. With the incoming air mass coming in from the west
rather than the north, it will bring drying to our region but not
much cooling. Daytime high temperatures will be near normal, in
the mid 70s to lower 80s. The drier air mass will support cool low
temperatures in the upper 40s to mid 50s.

&&

.LONG TERM...
(Saturday Night through Tuesday)
Issued at 439 AM EDT Wed Apr 10 2024

The surface high center will move out in the direction of Bermuda
from Sunday through Tuesday, but a ridge axis will extend itself
westward toward northeast Florida. In response, our surface flow
will become weak southeasterly. Meanwhile, a fairly strong 500 mb
high over the southwest Gulf will bulge northeastward as a ridge
axis, with upper heights peaking around Tuesday.

These factors will bring a day-by-day warming trend, with high
temperatures rising 5-10 degrees above normal. The prevalence of
high pressure at the surface and aloft will snuff out any chance
of rain.

&&

.AVIATION...
(12Z TAFS)
Issued at 648 AM EDT Wed Apr 10 2024

VFR conditions are generally expected to prevail this morning.
Clouds continue to stream in from the south and west ahead of a
storm system that will bring a line of showers and thunderstorms
through the area later this afternoon with more showers and storms
possible later tonight into early Thursday morning. There remains
some uncertainty with regards to timing, so expect adjustments to
that in future TAFs as the timing gets better pinned down. MVFR to
IFR ceilings and visibilities are expected with the rain, which is
forecast to be in and around the aerodromes much of the evening
and into early Thursday morning. Some clearing may be possible for
DHN and ECP near the end of the TAF period as winds turn more
westerly.

&&

.MARINE...
Issued at 439 AM EDT Wed Apr 10 2024

Southeast to south winds will gradually ramp up from now through
tonight in advance of a vigorous cold frontal passage on Thursday.
Southerlies are likely to peak as gales tonight and early
Thursday, or at least exhibit frequent gale-force gusts.
Following the cold frontal passage on Thursday, a shift to strong
westerlies is expected. Winds will start to decrease on Thursday
night, but it will take until Saturday or Saturday night for the
churned-up Gulf waters to settle down. High pressure will pass
east across the waters on Saturday night.

&&

.FIRE WEATHER...
Issued at 439 AM EDT Wed Apr 10 2024

Moderate to strong southerly flow will continue to moisten the air
mass. Showers and thunderstorms are forecast to arrive this
afternoon ahead of a cold front that will bring additional showers
and storms to the region later tonight into Thursday morning. High
dispersions and southerly transport winds are forecast ahead of the
showers and storms this afternoon for districts in southeastern
Alabama and southwestern Georgia. High dispersions are forecast for
all but the immediate coast following Thursday morning`s cold front
and again Friday as drier air works into the region.

&&

.HYDROLOGY...
Issued at 439 AM EDT Wed Apr 10 2024

Freshwater...
There is the potential for very heavy rain in our region from
late today into early Thursday morning. Precipitable water values
(PWATs) will be near or exceed record territory, or 1.9"+. This
richly moist air mass will juice up thunderstorms which could then
train along a stalled west-to-east boundary, bringing the heaviest
rainfall amounts. Widespread 2 to 4 inches of rain are forecast
across much of the region, and a few spots could very well pick
up 6 inches or more. With the larger than usual uncertainty
regarding rainfall totals and especially location of the heaviest
rain. Have therefore elected to expand the Flood Watch to include
all but LaFayette and Dixie Counties and make it start at 4PM
EDT/3PM CDT.

Riverine flooding will largely be dependent on where the heaviest
stripe of rain sets up, and which catch basin it happens over.
Some of the bigger differences are with how far north or south the
heaviest rain will set up. It could be over our Alabama and
Georgia counties, or it could be over our Florida counties. So
generally speaking, rivers most at risk of future flooding
include our more vulnerable basins such as the Pea,
Choctawhatchee, Muckalee and Kinchafoonee Creeks, Ochlockonee, and
Withlacoochee. All in all, this could potentially be a significant
heavy rainfall event for a portion of the region.

Saltwater...
Southerly gales across the northeast Gulf tonight and Thursday
morning will push saltwater onto the coast and raise water levels.
The uniquely surge-prone catchers-mitt shaped head of Apalachee
Bay could very well get a peak tidal anomaly near +4 feet around
or soon after sunrise on Thursday. This will be a few hours
removed from the lower high tide of the day, which will occur
along the Wakulla County coast around 5 am. Nonetheless, a brief
period of minor coastal flooding is likely. If the timing of the
wind and onshore push of water were to speed up a few hours faster
than forecast --- and therefore coincide with high tide --- then
more impactful moderate coastal flooding would be possible. Since
the prospect of minor coastal flooding is still a bit over 24
hours out, and confidence is affected by a mismatch with the high
tide cycle, will hold off for now on issuing a Coastal Flood
Advisory.

Moving around the bend toward the Taylor/Dixie coast, the peak
onshore push will come more squarely during a late morning low
tide over that way. While minor coastal flooding is possible, it
is less likely along the northern Nature Coast.

&&

.SPOTTER INFORMATION STATEMENT...

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.

&&

.PRELIMINARY POINT TEMPS/POPS...
Tallahassee   79  68  80  55 /  30  90  80  10
Panama City   76  67  74  57 /  70  90  40   0
Dothan        79  66  76  52 /  80  90  40  10
Albany        80  67  78  53 /  30  90  80  10
Valdosta      82  68  80  55 /  10  80 100  10
Cross City    82  68  77  55 /  10  70 100  10
Apalachicola  73  68  74  59 /  40  90  70   0

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch from 4 PM EDT /3 PM CDT/ this afternoon through
     Thursday afternoon for FLZ007>019-026>028-108-112-114-115-
     118-127-128.

     Wind Advisory from 8 PM EDT /7 PM CDT/ this evening to 11 AM EDT
     /10 AM CDT/ Thursday for FLZ007>010-012-014-015-027-114-115-
     118-127.

     Wind Advisory from 2 AM to 2 PM EDT Thursday for FLZ028-029-034-
     128-134.

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

     High Surf Advisory from 2 PM EDT /1 PM CDT/ this afternoon to 5
     AM EDT /4 AM CDT/ Friday for FLZ108-112-114.

     Wind Advisory from 2 PM this afternoon to 10 AM CDT Thursday for
     FLZ108-112.

     High Surf Advisory from 2 AM to 2 PM EDT Thursday for FLZ115.

GA...Flood Watch from 4 PM EDT this afternoon through Thursday
     afternoon for GAZ120>131-142>148-155>161.

AL...Flood Watch from 3 PM CDT this afternoon through Thursday
     afternoon for ALZ065>069.

GM...Gale Warning from 8 PM this evening to 3 PM EDT Thursday for
     GMZ730-755-765-775.

     Gale Warning from 2 PM this afternoon to 10 AM CDT Thursday for
     GMZ750-752-770-772.

&&

$$

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