AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE TALLAHASSEE FL
400 PM EST Fri Feb 10 2012
...Much colder weather arriving this weekend...
SHORT TERM (Tonight through Sunday NIGHT)...

A MID/upper level shortwave trough will pivot rapidly eastward along
the northern Gulf coast. Decent swath of synoptic support/QG forcing
ahead of this energy will overspread the area this evening. This
area of forcing is already supporting a large area of showers across
southern LA/MS. Global and HI-res model consensus agrees that this
area of showers will expand rapidly into our region this evening.
The QG forcing will align with upper level JET energy to support the
highest SHOWER concentration over the southern half of the
area...and especially coastal areas eastward through the SE Big
Bend. These areas are highlighted with high end 70% POPS, and an
argument could easily be made for higher CATEGORICAL PoPs. POP
GRADIENT will decrease to the north down to 40-50% up toward KDHN
and KABY. Still do expect some of the showers to reach this far
north, however some guidance members insist that the main area of
showers will be more broken in nature north of the FL border. Even
across the far south...this will be a high PoP...low QPF event, with
highest RAINFALL amounts LIKELY remaining under 1/4 inch. This will
be a quick hitting event AS the last of the organized showers are
expected to be exiting the Suwannee River Valley/I-75 corridor by
around 09Z. Surface based CAPE is essential NIL, and even elevated
INSTABILITY is lacking. Showalter indices are all positive and will
not include THUNDER mention. Low temperatures in the 40s.

Saturday:
Cold front will quickly pass east of the forecast area Saturday
morning with a much cooler and drier airmass arriving on BREEZY NW
winds. 850mb TEMPS will FALL below 0C over most areas by the end of
the day. Despite the strength of the cold AIR...excellent DIURNAL
mixing in the post-frontal environment will keep things seasonable
for afternoon highs. Looking for highs to RANGE from the lower 50s
north and west of a Dothan to Albany line, and range upward to the
lower 60s over the SE Big Bend zones. As mentioned above it will be
quite breezy for those with outdoor plans. NW winds sustained
between 15 to 20 mph with gusts near 25 mph common.

Saturday Night:
The cold air will arrive quickly with the setting of the sun. At
this time expecting temperatures by SUNRISE on Sunday to be
generally in the upper 20s...with middle 20s possible across the far
north. CURRENT statistical guidance shows lower/middle 20s for
many locations, however, MOS guidance almost always is too low in
these events with respect to the initial ADVECTION FREEZE...and have
taken this BIAS into account. This will only prevent a hard freeze.
Still anticipate a WIDESPREAD freeze even right down to the coast.
Combine these temps with a steady northerly breeze and WIND chill
reading will reach the upper teens to lower 20s. Will continue to
monitor the situation in case a wind chill ADVISORY becomes
necessary for early Sunday morning.

Sunday/Sunday night:
High pressure will settle southeast from the TN valley toward the
forecast area. The airmass in place and less efficient mixing
will result in a cool day. High temps will struggle into the lower
50s by the late afternoon. The close proximity of the high CENTER
will cause any light afternoon winds will go nearly CALM quickly
during the evening. These calm conditions combined with very dry low
levels suggest temps will fall quickly after SUNSET. Expect to see
normally colder areas fall below freezing potentially by late
evening, and SET up a long duration freeze. This appears to be the
night in which hard freeze conditions will be more likely. Low temps
for normally colder areas may drop into the lower 20s...with most
locations away from the immediate coast falling into the middle 20s.
As is usual with radiational cooling...the immediate coast and more
urbanized inland centers (such as downtown Tallahassee) should end
up a FEW degrees warmer, but still below freezing.

&&

.LONG TERM (Monday through next Friday)...
We`ll see another cold day to start the extended period with
possibly another widespread hard freeze Monday morning mainly east
of the Apalachicola/Chattahoochee Rivers. Surface high pressure will
be centered over the southeast CONUS with nearly zonal FLOW aloft on
Monday. The high will rapidly move east making way for the next low
pressure system that will bring a weak cold front with RAIN chances
to the region on Tuesday. This front will stall over or just south
of our FA late Tuesday/early Wednesday and then lift north as a warm
front Wednesday/Wednesday night as a stronger low pressure system
begins to develop over the southern plains. Showers/thunderstorms
will begin to overspread the region during the Thursday/Thursday
night time frame with the front forecast to push into the CWA on
Friday. After below NORMAL temps for Monday, the rest of the
extended period will have above seasonal temps.

&&

.MARINE
A weak area of low pressure will pass south of the forecast waters
this evening. In the WAKE of this low, winds will increase from the
Northwest later tonight and are forecast to reach advisory levels
Saturday morning. These advisory level conditions will continue
through Sunday morning. A period of GALE force gusts is possible
Saturday night and this potential will need to be monitored closely.
Winds and SEAS will decrease below headline criteria later Sunday
into the early portion of next week.

&&

.Aviation (through 18Z SAT)...Although VFR conditions should prevail
through the bulk of this TAF period, gradually lowering Vfr level
cigs will predominate the FCST for the remainder of this afternoon
and throughout much of the evening hours. Widespread light rain is
also expected to develop from SW to NE across the terminals, with
possible periods of moderate rain and MVFR level VIS this evening at
TLH, ECP, and VLD. Although some VFR level clouds could linger
behind the cold front for a while, Saturday should be dominated by
clearing skies, much cooler temps, and very gusty NW winds.

&&

.FIRE WEATHER...
Much cooler and drier air will be building in from the northwest on
Saturday on gusty Northwest winds. This very dry air combined with
sustained 15 mph or greater winds and Dispersions greater than 75
will result in a Red Flag WARNING for all of the Florida Big Bend
and Panhandle on Saturday. However, even though relative HUMIDITY
values will be extremely low over the SAME area on Sunday, will hold
off on a Fire Weather WATCH until future ERC values can be
determined. Over Southeast Alabama and Southwest and South Central
Georgia, will issue a Fire Weather Watch for Sunday for expected
long durations of relative humidity below 25 percent.