Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 061948
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
248 PM EST Fri Dec 6 2013
.NEAR TERM [Through Tonight]...
The sharply-defined front that extends from northwest GA through
central AL to Southeast LA has moved little during the day. Radar
continues to show spotty light showers over our far western zones.
Additional showers are beginning to develop upstream closer to the
front. All convection appears to be elevated behind the front at
this time. Temps have already surpassed 80 in a few spots as of 18
UTC with upper 70s elsewhere. Record highs will be challenged in a
few spots, but not TLH (83 in 1942).
Late in the day, the cold front will begin to advance southward once
again after it is nudged by a weak short wave. It is appearing less
likely that any surface based thunderstorms will be observed in our
forecast area ahead of the front.. We do allow for some elevated
convection across the northwestern zones during the first half of
the night. PoPs will be in the likely category north and west of
Dothan and taper quickly to less than 15% over the Southeast FL Big
Bend. Overnight lows will be mild ahead of the from in to lower 60s.
Areas west of a line from roughly Destin to Dothan will drop into
the lower to mid 50s. Fog will once again be a possibility, with the
greatest likelihood and coverage over the southeastern half of the
.SHORT TERM [Saturday Through Sun Night]...
The large scale pattern commences highlighted by a broad trough over
Wrn states, and a ridge centered over extreme Wrn Atlc with Atlc
high just off S FL coast. This places local area in broad cyclonic
SWLY steering flow. However, exiting shortwave has weakened ridge. At
surface, this allows formerly quasi-stnry front to be pushed SEWD
with now SW-NE cold front bisecting local area. Absent any noted
forcing and SW steering flow, and with front bumping into low
level Atlc ridge, it begins to re-orient itself more W-E and hangs
up. Guidance indicating that most rain should be light and post-
frontal so the focus will be across Nrn third of our CWA. This
reflected in model soundings which at 18z Sat show around 1.6 inch
PWAT both ahead and behind the front. In its wake, a substantially
colder airmass begins to slide in during the day especially for NW
quarter of area which makes temp forecast tricky an highly
dependent on position of front and depth of clouds. Current
thinking is that the front will make it very close to Tallahassee
during the afternoon before stalling. To the NW, temperatures will
fall behind the front, with max temperatures in SE Alabama likely
occurring in the morning. Southeast of the front, the unseasonably
warm weather will continue.
During Sat night, Wrn trough re-intensifies and moves east of
Rockies allowing Ern upper ridge to re-intensify Nwwd. At surface,
high over OH/TN Valleys shift ewd while area of low pressure
over NW Gulf lifts Nwd. This will allow front to retreat rapidly
to the N/NW with overrunning north of the front inducing small
chance of stratiform rain over mainly Nrn most counties. It begins
to wash out by sunrise Sun. This will result in the warm airmass
spreading back across the entire forecast area for Sunday. Under
light winds and ample low level moisture...a good chance of area
of fog...locally dense especially Ern third of area.
On Sun, trough moves further Ewd with series of embedded impulses
ejected Ewd kicking Atlc high/ridge to vcnty Bahamas. In wake of
dissipating front, low level onshore flow will boost temps and
may account for early fog. During the day, low pressure in Nrn
gulf merges with next cold front approaching from west. By late
Sun night, this second front approaches NE Gulf region with sct
convection reaching Wrn most portions of CWFA.
Will go with 30-0% N-S POP gradient Sat night-Sun, and 40-20%
NW-SE gradients Sun night. Inland lows Sat night from around 50 SE
AL to mid-upper 50s Ern counties rising to around 60 Sun night.
Very sharp temp gradient on Sat with frontal boundary. Expect highs
Sat from low-mid 50s Wrn most counties to upper 70s SE Big Bend.
Highs Sun low-mid 70s North to 80 SE Big Bend.
.LONG TERM [Monday through Friday]...
The period starts with a strong cold front moving into the area.
There is some disagreement between the EURO and GFS as to the timing
of the frontal passage. The EURO shows the front approaching our
area on Monday evening with a gradual passage by Tues.
night/Wednesday morning. The GFS is bringing the front through about
12 hours earlier and quickly exiting the area. Cooler and drier air
will move in. Wednesday will be the coolest day before temps begin
to edge up. Thurs will be the driest day with PWATs down to bone dry
0.20 inches. On Wednesday with highs in the low to mid 60s.
Wednesday`s lows will range from upper 30s in NW Alabama to low 50s
in the FL Big Bend. Temperatures remain cool through Friday with mid
40s at night and upper 60s during the day.
[Through 18 UTC Saturday] Ceilings are forecast to lift to VFR at
most terminals this afternoon. However, a few spots could hang on to
MVFR. For tonight, IFR cigs will work their way northward from the
coast between 23-04 UTC. There appears to be enough vertical motion
to warrant mention of some light drizzle as well. Visibilities may
drop to IFR in any drizzle areas. This is most likely at TLH and
VLD. After a frontal wind shift, ceilings will be only slow to
Southerly flow will continue across the waters this eve ahead of an
approaching the cold front. Sea fog is likely especially near the
coast. Winds over the western waters will become offshore late
tonight into Saturday, before becoming southeasterly again on
Sunday. Winds and seas are currently forecast to remain below
headline criteria through the forecast period.
Low dispersion will set in tonight and persist through Sunday.
Partially for this reason, fog will remain a possibility in areas
that stay in the warm humid air ahead of a front that will stall
across the region roughly along a VLD-TLH-AAF line on Saturday. A
stronger cold front will cross the region on Tuesday. Drier air will
arrive behind this front. However, critical RH will not be reached
and red flag criteria are not anticipated.
Total rainfall amounts over the next 5 days should range from
roughly an inch northwest of Dothan to less a quarter inch over
the southeastern half of the HSA. This will have only minimal
impacts on area rivers and streams.
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 64 73 57 77 62 / 30 30 20 10 20
Panama City 64 67 56 75 66 / 40 40 20 20 30
Dothan 55 59 52 75 63 / 50 50 30 20 30
Albany 63 67 54 74 62 / 40 50 30 20 30
Valdosta 63 75 58 78 61 / 20 30 20 20 20
Cross City 60 78 57 80 61 / 10 20 10 10 20
Apalachicola 66 70 60 73 66 / 20 30 20 10 20