Area Forecast Discussion
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495
FXUS62 KTAE 290711
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
311 AM EDT Mon Sep 29 2014

...Heavy Rainfall is Possible Today in South-Central Georgia and
the Florida Big Bend...

.Near Term [Through Today]...
Heavy rain has had a difficult time materializing across most of the
area, despite a tropical airmass in place with an upper trough
approaching. The main limiting factor seems to be the convective
complexes in the Gulf, which are disrupting low-level inflow into
our forecast area. Guidance has insisted since yesterday that this
will change as the thunderstorms over the Gulf weaken, but so far
that has not happened. The HRRR has been particularly bad with this
scenario, continually over-forecasting convection in our area in the
first few hours of its forecast for most of the night. Because of
this mesoscale issue, confidence remains low on the convective
evolution and rainfall amounts across the area for the remainder of
today. As long as significant convection remains over the Gulf, most
of the area will not see heavy rain with the exception of a few
points along the coast.

That being said, satellite imagery has shown some gradual weakening
of the MCS west of Tampa, and there has been a slow uptick in the
rain and embedded convective coverage closer to our coast. The
general movement of this has been more northerly rather than
easterly as well, so perhaps things are beginning to change a
little. However, the threat seems to have diminished enough across
the northwest portions of the area to cancel the watch there. Still
do not feel comfortable canceling the entire watch just yet though
as there still appears to be a window for heavy rainfall and
training echoes across portions of the area through this afternoon.
The greatest potential appears to be across the Florida counties
near the coast, but cannot completely discount portions of south
central Georgia either. As the morning progresses, the western
portions of the watch area may be able to be cancelled early, as
well as the northern portions if convection does not develop there
by mid to late morning. At any rate, we will be mostly rid of this
system in the next 24 hours, and good riddance as it has been a
tough one to forecast.


.Short Term [Tonight Through Wednesday]...
A shortwave upper level trough will swing northeastward through the
Appalachian mountain range, lifting the stationary surface front
currently laid out across NE FL from Cross City to Jacksonville
today and tonight, finally pushing it out of the area Tuesday.
Tonight, chances for showers and thunderstorms will be most likely
(60-70%) in south-central Georgia and the Florida Big Bend, with
lower chances (30-50%) to the west. The highest rainfall amounts
will fall during the daytime hours, but isolated areas in south
Georgia and the Big Bend (where PWATs will still be over 2") may see
heavy rainfall early in the night. Tuesday through Wednesday,
chances for showers and thunderstorms will be much lower (30% or
less), with the highest chances staying in the eastern Big Bend.
Lows tonight and Tuesday night will be in the mid to upper 70s.
Highs will be in the mid 80s Tuesday, mid-upper 80s Wednesday.


.Long Term [Wednesday Night Through Monday]...
After a very wet pattern over much of the near and short term
periods, we expect to have a brief break in the unsettled weather
later on Tuesday and through Wednesday, as both Sfc and upper level
ridging build in for a short time. Thereafter, showers and
thunderstorms are expected to return to the fcst in earnest on
Thursday and Friday, as the strongest cold front of the season thus
far approaches from the NW. This cold front is expected to bring a
real taste of fall to the region by Saturday and Sunday, with low
temps possibly reaching the lower to middle 50s over the interior on
Sunday morning, with much drier air also building in under the NW
flow. High temps will still be very close to climo levels, however,
generally in the lower to middle 80s on Sat and Sun. Before the
frontal passage, above normal temperatures are expected to persist,
with the warm and humid air struggling to budge.


&&

.Aviation...
[Through 06Z Tuesday] Periods of rain and low cigs are expected
through most of the day with MVFR to IFR conditions. Some clearing
is expected around DHN and ECP by the end of the day as the rain
exits that area.


&&

.Marine...
A stationary front will finally exit the area Monday and Monday
night, shifting the winds from southerly to westerly then northerly,
returning back to southerly by mid week. Wind speeds will remain
below headline criteria until early in the weekend, when another
frontal passage may increase winds to cautionary levels.


&&

.Fire Weather...
Hazardous fire weather conditions are not expected over the next few
days.


&&

.Hydrology...
We have started to trim back the flash flood watch from northwest to
southeast, and additional trimming is likely through the day today
as convection gradually moves to the east. The heavy rain threat is
isolated, so main stem river flooding is unlikely. Isolated spots
within the watch area could still pick up 4-6" of rain in a short
period of time, but most locations will not see that much.


&&

.Preliminary Point Temps/PoPs...

Tallahassee   80  69  86  68  89 /  90  60  20  10  20
Panama City   83  70  86  71  87 /  90  40  20  10  20
Dothan        80  66  86  65  88 /  80  40  10  10  10
Albany        78  66  85  65  87 /  90  50  10  10  10
Valdosta      81  67  85  65  87 /  90  70  20  10  20
Cross City    83  70  86  67  88 /  90  60  30  20  20
Apalachicola  82  71  84  71  85 /  90  50  20  20  20

&&

.TAE Watches/Warnings/Advisories...

FL...Flash Flood Watch through this evening for Calhoun-Coastal Bay-
     Coastal Dixie-Coastal Franklin-Coastal Gulf-Coastal
     Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden-Inland Bay-
     Inland Dixie-Inland Franklin-Inland Gulf-Inland Jefferson-
     Inland Taylor-Inland Wakulla-Lafayette-Leon-Liberty-Madison.

GA...Flash Flood Watch through this evening for Baker-Ben Hill-
     Berrien-Brooks-Colquitt-Cook-Decatur-Dougherty-Grady-Irwin-
     Lanier-Lee-Lowndes-Mitchell-Thomas-Tift-Turner-Worth.

AL...None.
GM...None.

&&

$$

NEAR TERM...DVD
SHORT TERM...MOORE
LONG TERM...GOULD
AVIATION...DVD
MARINE...MOORE
FIRE WEATHER...DVD
HYDROLOGY...DVD






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