Severe Thunderstorm Warning 470, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1004 AM EST WED DEC 23 2015

.Near Term [Through Today]...

At 15z regional satellite analysis and radar data depicted a few
areas of interest as it pertains to the evolution of today's
weather. Two MCS' sandwich the region, with one over east-central
Alabama and another off the western peninsula of Florida.
Isentropic ascent over outflow from the northernmost MCS has
resulted in continual moderate to heavy rainfall across our
southeast Alabama counties. In the same vicinity was a long-lived
supercell moving through southern AL. Outside of this storm,
severe weather is not anticipated in this region this morning. The
outflow from the northernmost MCS and the outflow from the
southernmost MCS (moving northward) will be the only source of
surface based convection later this afternoon. As a weak southern
stream shortwaves moves overhead later today, should there be
enough instability and the surface based features be strong
enough, there is the potential for a few strong to severe
thunderstorms. The main threats with these storms would be
damaging winds or a tornado. Just how long the low cloudiness
hangs in this morning will be very important as to the eventual
destabilization of the boundary layer. The flash flooding threat
continues to decrease this morning as rain rates over SE Alabama
have not been that impressive. Though due to the uncertainty of
this afternoon's forecast and an environment supportive of heavy
rain, will keep the watch going for now. On average though, areas
that receive moderate to heavy rain today should see totals
somewhere in the 1-2" range, with isolated 3" amounts.

&&

.Aviation...
[Through 12Z Thursday]...

IFR ceilings have held longer than expected this morning. Due to
poor model performance today, uncertainty remains high as to when
ceilings will either scatter or lift. For now, anticipate IFR
conditions for much, if not all of the TAF.

&&

.Prev Discussion [259 AM EST]...

.Short Term [Tonight Through Friday]...
Deep southwesterly flow will continue into the overnight hours,
keeping the atmosphere moist and modestly unstable. However, with
the primary shortwave lifting into the Great Lakes overnight,
forcing will be on the decline. This should lead to an overall
decrease in convective coverage tonight, with the best rain
chances retreating to the northwestern portion of the area.

For Thursday, the ridge over the western Atlantic will begin to
nose back to the west, pushing the corridor of deepest moisture
westward as well. This will leave the best chances for
thunderstorms in the Florida Panhandle and SE Alabama for
Thursday. Given decent instability and marginally sufficient deep
layer shear, a few of the storms could be strong on Thursday, with
SPC maintaining a marginal risk for severe storms over the western
half of the forecast area.

The ridge will become more firmly established by Christmas Day,
with record warmth becoming the main story. High temperatures will
likely reach at least the lower 80s for near all areas away from
the immediate coast. Mid 80s will be possible over the eastern
half. The high temperature at Tallahassee will likely break the
daily record (80F), and possibly the monthly record for December
(84F).

.Long Term [Friday Night Through Wednesday]...
The warm weather will continue into the week after Christmas with
the upper ridge remaining firmly planted over the Western Atlantic
and southeastern states. Expect mostly dry conditions through the
weekend with temperatures well above normal for late December. The
next chance of rain will likely be early next week, as a deep
upper low ejects from the Southern Plains and drives a cold front
eastward along the Gulf Coast. The timing and strength of this
system remain highly uncertain at this time.

.Marine...
Southerly winds will increase over the waters today, with
conditions over the western waters reaching Small Craft Advisory
levels during the daytime hours. Conditions will begin to improve
this evening, with light southerly to southeasterly winds expected
through Friday.

.Fire Weather...
There are no fire weather concerns.

.Hydrology...
The NWP guidance consensus is no longer forecasting the unusually
high QPF values we were seeing over the past several runs. While
it's tempting to cancel our current Flash Flood Watch, we would
prefer to see how the rain pattern evolves later this morning
before making that call.

Modest rises are expected on area rivers given the recent and
expected rainfall amounts. The Apalachicola at Blountstown will
reach minor flood stage today as a result of releases at Woodruff
Dam. Otherwise, the Choctawhatchee may reach flood stage in
Florida later in the week, depending on exactly how much rain
falls across the basis through tonight.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   75  69  80  65  83 /  60  50  20  10  10
Panama City   75  69  76  68  78 /  40  50  30  20  10
Dothan        77  68  79  66  81 / 100  60  50  20  10
Albany        76  67  80  65  83 /  80  50  30  10  10
Valdosta      78  68  81  65  83 /  60  30  10  10  10
Cross City    79  69  84  65  85 /  40  20  10  10  10
Apalachicola  74  69  76  66  77 /  50  50  20  10  10

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Flash Flood Watch through Thursday morning FOR Calhoun-Central
     Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland
     Gulf-Jackson-North Walton-South Walton-Washington.

     High Rip Current Risk until 8 PM EST /7 PM CST/ this evening FOR
     Coastal Bay-Coastal Gulf-South Walton.

GA...Flash Flood Watch through Thursday morning FOR Baker-Calhoun-
     Clay-Dougherty-Early-Lee-Miller-Quitman-Randolph-Seminole-
     Terrell.

AL...Flash Flood Watch through late tonight FOR Coffee-Dale-Geneva-
     Henry-Houston.

GM...Small Craft Advisory until 7 PM EST this evening FOR Coastal
     waters from Apalachicola to Destin FL out 20 NM-Waters from
     Apalachicola to Destin FL from 20 to 60 NM.

&&

NEAR TERM...HARRIGAN
SHORT TERM...CAMP
LONG TERM...CAMP
AVIATION...HARRIGAN
MARINE...CAMP
FIRE WEATHER...FOURNIER
HYDROLOGY...FOURNIER/CAMP