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812
FXUS62 KTAE 121128
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
728 AM EDT Sun May 12 2013

.UPDATE...
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Aviation discussion for 12Z TAF package. Remainder of discussion
unchanged.
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&&

.NEAR TERM [Through Tonight]...
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As of 07 UTC, the area radars were devoid of any rain although an
initial weak surface cold front was still approaching our area. The
front`s position at that time appeared to be right near the
northwest corner of our forecast area. The air mass ahead of the
front was still characterized by mid-60s dew points. Mid-level
clouds  have prevented much fog development despite light winds.
With both global and high-resolution models failing to generate
any additional precipitation through at least 14 UTC ahead of the
front, we opted for a dry forecast through that time. There will
still be a small chance of an isolated shower or two ahead of the
cold front in the southeast part of our area from the late morning
into the afternoon. High resolution guidance appears to be very
consistent on the idea of this being relatively shallow convection
with weak updrafts. Therefore, the forecast only includes rain
showers at this time, with thunderstorms not mentioned. PoPs were
capped at 20%. Highs today will be warmest in the southeast,
ranging from mid-80s there to upper 70s in the northwest.
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&&

.SHORT TERM [Monday Through Tuesday]...
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The peak of the anomalously deep long wave trough over the eastern
CONUS will be Monday afternoon, when the trough`s axis will extend
from eastern Canada to the northeast Gulf of Mexico. 500 mb heights
are then forecast to rise nearly 100 meters over our forecast area
by Tuesday afternoon. With an extremely dry column and sinking air
aloft, clouds (other than a few high, thin CI) will be difficult to
come by. Our low temperature forecast for tonight is slightly
warmer  than the MOS consensus, as MOS frequently goes too cold
immediately behind a cold front (when the winds don`t go calm and
mixing prevents rapid cooling). Highs will "only" reach the mid to
upper 70s on Monday, which is closer to what we would expect in
late March. We think the "coldest" morning will be on Tuesday, as
a high pressure ridge becomes centered over northwest FL. The
tightly-clustered MOS consensus calls for record lows in the mid
40s at our normally coldest sites, away from the coast and cities.
This includes the Tallahassee airport. A warming trend will begin
Tuesday as highs reach 80 degrees.
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&&

.LONG TERM [Tuesday Night through Saturday]...
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The period will begin with an upper level trough pulling away to
the northeast and short wave ridging building in from the west.
The upper ridge axis will reach our zones on Wednesday and then be
shunted to the east by the next trough that will impact the area
late in the week. The GFS is more diffuse than the Euro with the
energy in this system and also more progressive. At the surface,
high pressure will drop south across the area on Tuesday and then
remain in place just south of the area through the period. This
ridge will work to hold off any would be shower activity until
Friday and Saturday when a front will approach from the north.
Look for 20-30 PoPs on those days. Max temps will be near normal
(mid 80s) through the period. Overnight lows will be a bit below
normal Tuesday night and then return to normal after that time.
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&&

.AVIATION...
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[Through 12Z Monday] The IFR conditions observed at TLH and ECP at
TAF issuance (and the MVFR at VLD) will all lift/scatter to VFR by
13Z...14Z at the latest. After that, VFR will then prevail through
through the remainder of the TAF period.
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&&

.MARINE...
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The pressure gradient was very flat this early morning, despite the
approaching cold front. This will change later tonight however as
the pressure gradient tightens considerably behind a cold front. It
will be close, but the NWP guidance wind speed consensus keep our
sustained winds a knot or two below advisory levels (20 KT).Winds
and seas will subside a bit on Monday, but then increase to
exercise  caution levels Monday night.
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&&

.FIRE WEATHER...
A drier air mass is expected over much of the area today except the
Florida Big Bend, with RH possibly reaching the low 30s in some
areas. However, this will not be sufficient to meet any red flag
criteria. On Monday, red flag conditions cannot be ruled out,
particularly over Florida. There remains some uncertainty on winds
and ERC levels, but RH will be low enough. Red flag conditions seem
unlikely in Alabama and Georgia due to KBDI and fuel moisture
requirements respectively.

&&

.HYDROLOGY...
Rainfall totals on Saturday were minuscule, so we don`t expect any
hydrology issues for the next several days.

&&

.PRELIMINARY POINT TEMPS/POPS...
Tallahassee   83  54  78  45  80 / 10   0   0   0   0
Panama City   81  58  78  56  78 / 10   0   0   0   0
Dothan        79  50  74  50  82 / 10   0   0   0   0
Albany        80  50  75  47  80 / 10   0   0   0   0
Valdosta      85  53  76  46  79 / 10   0   0   0   0
Cross City    83  59  78  45  80 / 20  10   0   0   0
Apalachicola  81  59  76  52  76 / 20  10   0   0   0

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.

&&

$$

NEAR TERM/FIRE WEATHER...Lamers
SHORT TERM/MARINE/HYDROLOGY...Fournier
LONG TERM...Wool
AVIATION...Lamers/Wool