Area Forecast Discussion
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824
FXUS62 KTAE 152039
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
339 PM EST Sat Nov 15 2014

.Near Term [Through Tonight]...
Very tenuous low temp fcst for tonight, as most of the signals in
the numerical guidance, Hi-res models, and locally run ensembles
are indicating a very high probability of low clouds (1500-2500
ft) developing to our east and moving westward overnight. There is
already a fairly healthy CU field that is rapidly moving westward
from JAX`s CWA, and is close to encroaching on our SE FL Big Bend
counties. Some of these clouds may dissipate around sunset, but
should reform as stratus or stratocu sometime this evening, and
how quickly it develops and how far to the north and west it is
able to propagate will ultimately determine low temps and
dewpoints for tonight. For the time being, kept lows fairly
conservative given the situation and used a Hi-res guidance blend,
which is generally just a few degrees higher across the board
(with lows ranging from the upper 30s well to the NW to around 50
to the SE of Cross City). Highly doubt these will have to be
adjusted downward, but they may very well need a 3-5 degree bump
upward on this evening`s update.

.Short Term [Sunday Through Monday Night]...
Temperatures will moderate on Sunday as onshore flow increases
ahead of an approaching cold front. Expect to see high
temperatures range from the upper 60s to lower 70s across the
area.

Clouds and deep moisture will increase quickly late Sunday into
Sunday night as low pressure develops along the central Gulf Coast
ahead of a strong shortwave digging into the Southern Plains.
While a large area of rain is expected to develop along and ahead
of the front, uncertainty remains concerning the potential for a
few strong to severe storms along the Gulf Coast Monday morning.
Kinematically, the shear is forecast to be sufficient with deep
layer shear of 50-60kt and low-level shear of at least 30kt. The
main question will be the recovery of the low-level airmass from
its current cool and rather dry state. All of the available
guidance agrees that there will be a narrow band of surface-based
instability near the Gulf Coast Monday morning as dewpoints
recover into the mid 60s. The available convection-allowing
guidance is a bit more bullish with the instability, indicating
1000-1500j/kg of CAPE generally along and south of I-10. This
instability coupled with the expected shear could would certainly
support a few strong to severe storms along and ahead of the cold
front. Will need to continue to monitor this situation through the
weekend.

The front will cross the forecast area during the day on Monday,
with the slower timing of the ECMWF/NAM/Canadian preferred over
the faster GFS. Precip should end from west to east by late
afternoon/evening with much colder air moving into the region
behind the front on northwesterly winds. Temperatures by Tuesday
morning will range from the upper 20s in the northwest to the
upper 30s in the southeastern Big Bend.

.Long Term [Tuesday Through Saturday]...
Arctic high pressure will plunge towards the Gulf coast on Tuesday
behind the exiting cold front. Temperatures will remain well below
normal through at least Thursday. Highs on Tuesday will likely
only reach the 40s to lower 50s, warming to the lower to mid 50s
on Wednesday and the upper 50s to lower 60s on Thursday.

Overnight lows will be 20 to 25 degrees below normal Wednesday and
Thursday mornings as the center of the high pressure becomes
ideally situated over the forecast area for strong radiational
cooling. The current forecast has lows in the lower to mid 20s
(near or below current records) away from the coast Wednesday
morning. Even these values may be a bit warm, with some guidance
calling for even lower values. Thursday morning lows may be a bit
warming with values in the upper 20s to around 30.

A slow warmup should begin by late in the week as the airmass
modifies and allows temperatures to approach normal values once
again.

&&

.Aviation...
[Through 18Z Sunday] As mentioned above, main concern will be the
development and westward propagation of MVFR Cigs late tonight and
into Sunday morning. At the time of composing this Taf package,
most of the guidance was indicating these Cigs would be most
likely to develop across the eastern half of the CWA (TLH, ABY,
and VLD), so currently have VFR conditions prevailing at DHN and
ECP. However, as more guidance has come in, this will need to be
re-evaluated on the 00Z package tonight for possible impacts
further west, as well as earlier onset times further east.

&&

.Marine...
Easterly winds tonight and early Sunday will become southeasterly
and then southerly Sunday night while increasing to exercise
caution levels. Advisory level conditions are expected on Monday
just ahead of a strong cold front as well as behind the front as
winds shift to the northwest. Strong offshore flow will continue
into Tuesday before diminishing into Wednesday as high pressure
builds over the waters.

&&

.Fire Weather...
Relatively high RH is expected the next couple days with a
wetting rain expected on Monday. Dry air will arrive behind the
cold front by Tuesday and linger through the middle of the week.
Red flag conditions may be possible behind the front, but are far
from certain at this point.

&&

.Hydrology...
Sunday night and monday rainfall amounts will generally be
between .5 and 1.25 inches, with the highest amounts over SE
Alabama and the Florida Panahandle. With current river levels
quite low, these amounts are not expected cause any problems.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   44  72  60  73  35 /  10  10  30  80  10
Panama City   47  70  63  69  36 /   0  10  60  80  10
Dothan        39  68  59  64  29 /   0  10  70  80  10
Albany        39  70  58  68  31 /  10  10  50  80  20
Valdosta      45  72  57  73  35 /  10  10  20  80  50
Cross City    49  76  58  75  39 /  10  10  10  70  50
Apalachicola  51  68  64  74  38 /  10  10  40  80  10

&&

.TAE Watches/Warnings/Advisories...

FL...High Rip Current Risk until Midnight EST tonight for Coastal
     Gulf.

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

&&

$$

NEAR TERM...GOULD
SHORT TERM...CAMP
LONG TERM...CAMP
AVIATION...GOULD
MARINE...CAMP
FIRE WEATHER...GOULD
HYDROLOGY...CAMP








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