Area Forecast Discussion
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923
FXUS62 KTAE 202029
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
329 PM EST Sat Dec 20 2014

...Heavy Rain and Severe Weather Possible Early Next Week...

.Near Term [Through Tonight]...
The afternoon analysis continues to show a stationary frontal
boundary draped just offshore of the northern Gulf coast. North of
this boundary, cool northeast surface flow continues across the
local area with lots of cloudiness. Scattered patches of light
rain also continue to stream northeastward with amounts ranging
from a trace to a few hundredths. Expect little change overnight
with the same general pattern remaining in place. Lows will range
mainly from the middle 40s to the lower 50s across the area.


.Short Term [Sunday Through Monday Night]...
Southwesterly flow aloft will persist through this period with
occasional ripples of energy passing by. At the surface, we will
continue to see a weak wave of low pressure over the North Central
Gulf of Mexico with a stationary front stretching northeastward from
it across the FL Big Bend from Sunday through Sunday night.
Isentropic ascent over the boundary will provide sufficient forcing
to produce periods of mainly light rain Sunday and Sunday night.
PoPs will be high, ranging from 50 northwest of Dothan to
categorical over the eastern FL Big Bend and South Central GA. Max
temps will be on the cool side Sunday, ranging from the upper 50s
north to the upper 60s southeast. Abundant cloud cover will limit
the diurnal temp range with lows Sunday night mainly in the 50s and
any 40s limited to areas north of an ABY-DHN line. The front will
begin to inch northward on Monday as onshore flow strengthens ahead
of a developing system to the west. Max temps will be some 6-8
degrees warmer than on Sunday. Precipitation will mainly be in the
form of stratiform rain initially. However, it will become more
showery in nature beginning late Sunday night. Some elevated
thunderstorms will be possible across the southeastern half of the
forecast area with surface based convection largely limited to the
marine area. By Monday night, we will begin to see SBCAPE increase
gradually inland in an increasingly sheared environment. An isolated
strong to severe storm cannot be ruled out near the coast.


.Long Term [Tuesday Through Saturday]...
The main event continues to be centered on Tuesday and Tuesday night
as the upper trough in the plains becomes deeply amplified and
begins to move east. Deep layer shear will increase to 45-60kt
during this time. We are starting to get a bit more confident that
there will be sufficient destabilization to warrant a threat for
severe weather. SPC has most of our FL zones along and south of I-10
outlooked for a 15% chance of severe storms within 25 miles of a
point, the equivalent of a slight risk. The inland extent of any
severe risk will be entirely dependent on how much destabilization
ultimately occurs. Another concern will be heavy rain and potential
flooding. See the hydrology section below for details. The front
should be east of the area by 18Z Wednesday and will usher in a
noticeably cooler and drier air mass. Highs on Christmas Day will
only be in the upper 50s to around 60. Lows both Christmas Eve and
Christmas nights will be down into the 30s, but should remain
safely above freezing. A moderating trend in temps will commence
Friday. The next frontal system will approach from the west on
Saturday with rain chances returning to the forecast for the end
of the week.

&&

.Aviation...
[Through 18Z Sunday] Ceilings will gradually lower through the
period with northeast surface flow. Expect MVFR to become more
common this evening with IFR prevailing late tonight. Low clouds
are expected to persist through the morning hours on Sunday with
IFR continuing.

&&

.Marine...
Light to moderate easterly flow will prevail through the weekend.
Winds will then veer to onshore early next work week as a warm front
lifts north of the waters. These winds could reach cautionary levels
ahead of a cold front on Tuesday and possibly advisory levels
Tuesday night. Strong to severe storms will precede the front which
will sweep across the waters on Wednesday. Solid advisory level
westerly winds will arrive in its wake and we could even see some
gale-force gusts. Winds will veer to the northwest and subside below
headline criteria by Thursday morning.

&&

.Fire Weather...
Low level moisture will be abundant over the next few days with
drier air moving in on Wednesday. Red flag conditions are not
expected over the next week.

&&

.Hydrology...
An unsettled pattern will mean high rain chances from Sunday through
Tuesday night. From Tuesday morning through early Wednesday, much
of the area could see 3 to 4 inches of rain and that will be on top
of an inch to inch and a half in the preceding days. These 4-day
totals in excess of 5 inches will be broad averages and isolated
totals could be several inches higher. Since it has been dry for
several weeks now, the overall flood threat will be mitigated
somewhat. However, some localized areal flooding will be possible
during this time in the areas that get the heaviest rains. Riverine
flooding may become a concern by midweek as well.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   51  63  54  72  60 /  30  70  70  50  50
Panama City   53  63  57  71  64 /  30  70  70  50  50
Dothan        48  59  50  67  58 /  20  60  60  40  50
Albany        47  59  48  67  56 /  20  70  70  40  50
Valdosta      50  61  54  71  58 /  30  80  80  50  50
Cross City    53  69  58  75  61 /  40  80  80  60  50
Apalachicola  54  64  58  70  63 /  40  70  70  50  50

&&

.TAE Watches/Warnings/Advisories...

FL...None.
GA...None.
AL...None.
GM...None.

&&

$$

NEAR TERM...DVD
SHORT TERM...WOOL
LONG TERM...WOOL
AVIATION...DVD
MARINE...WOOL
FIRE WEATHER...MCDERMOTT
HYDROLOGY...WOOL






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