Area Forecast Discussion
Issued by NWS
FXUS62 KTAE 011532
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1032 AM EST Sun Dec 1 2013
.NEAR TERM [Rest of Today]...
The large scale regional pattern is highlighted a very broad
cyclonic flow. A weak shortwave was noted moving Ewd from Plains
thru to Cntrl Gulf spreading some higher level clouds Ewd. At
surface, mid-Atlc high has moved offshore (and will weaken with
approaching shortwave) with weak ridging Swwd across NE Gulf region.
Likewise coastal trough was weakening leaving weak NE flow across
our area. Dew points running 3 to 7 degrees higher east of
Apalachicola River and up to 8 to 14 degrees west of river
compared to same time yesterday highlighting modification of
airmass. 12z TAE sounding shows low level moisture trapped below
subsidence inversion around 810mb supporting considerable low
clouds. Additionally satellite shows some lower based moisture
over the Gulf moving onshore. This added moisture plus NE flow
was sufficient to maintain low clouds this morning from 5 hundred
Ern most counties to 3k Wrn most.
Lacking full sun and it being December, lower ceilings should linger
past midday, especially for Ern counties. Hi Res guidance and
satellite also imply that some lower clouds will continue to move
onshore from Gulf later this aftn impacting mainly Wrn counties
and aided by meager shortwave lift, some isold light showers or
sprinkles are possible with Gulf moisture later this aftn. Expect
mixing out to P/C to vrbly cloudy Wrn counties but vrbly to M/C
cloudy Ern counties with increasing higher clouds spreading Ewd
making temp forecast tricky. However, 15Z temps in line with GFS
and a few degrees above CAM so will not do any updates. Expect
that high temperatures should only be in the mid to upper 60s
across the area. Shortwave to reach LWR MS Valley to E/Cntrl Gulf
by sundown with added higher clouds.
.SHORT TERM [Tonight through Tuesday]...
A weak short wave trough will translate quickly eastward over the
Gulf Coast States tonight and Monday, followed by zonal flow at
500 mb. The forecast surface weather pattern appears rather
"muddled", however, which may explain why the MOS PoP from the
various models is so varied. There will be a very weak pressure
pattern across our forecast area, with a weak frontal system
(currently developing over Central FL) remaining to our south
through Monday night. On Tuesday this front will move slowly to our
north as a warm front.
The most obvious focus for rain would be the short wave trough
passing through our region late tonight and Monday, but it doesn`t
appear very strong and the MOS PoPs range from 10 to 20%. More
significant differences arise Tuesday afternoon as the NAM and ECMWF
MOS PoPs are in the 40-70% range over our western zones, while the
GFS MOS PoP is only 10-20% across our entire forecast area. While
the warm front may serve as a focus for rain on Tuesday, it`s a
rather subtle feature and the GFS and ECMWF lack mid-upper lever
moisture. Based on the lack of a well-defined system and overall
model agreement, we will keep the PoP in the 20-30% range. The
consensus of QPF is less than a quarter of an inch, and with almost
no SBCAPE (over land) we don`t expect any thunderstorms.
Temperatures will be a little above average, with lows generally in
the upper 40s and highs around 70 Monday, then lower to mid 70s on
Tuesday. Usually this time of year when temperatures are above
average there is a higher risk of fog. Indeed, areas of fog will be
possible Tuesday morning as a weak warm front moves inland.
.LONG TERM [Tuesday through Saturday]...
At the start of the period, a deep trough will be digging into the
western states with mainly zonal flow across the southeast. As the
trough continues to deepen by the mid to latter part of the week,
an upper level ridge will build over the southeast Gulf of Mexico
and northwest Caribbean. With this ridge in place, above average
temperatures are expected with mostly dry conditions, but rain
chances may gradually increase towards the end of the period
depending on how much the upper level ridging breaks down and how
far east the trough advances by that time.
.AVIATION [Through 12z Monday]...
It appears that ECP/DHN should stay VFR. At TLH/ABY/VLD, conditions
should only slowly improve with ceilings finally rising above MVFR
levels in the 16z to 19z timeframe. BKN cloud deck around 3500 ft
should persist into the evening and overnight hours. With weaker
NE low level late tonight, chance for low clouds and fog are less
than this morning. Best forecast is marginal MVFR vsbys
Winds and seas will subside greatly later today as an area of high
pressure essentially "breaks off" across the coastal waters tonight
and Monday. Winds will become south to southeast Tuesday, and
increase slightly mid to late week as the area of high pressure
moves east into the Atlantic Ocean.
Moisture levels will continue to increase through the week, thus
fire weather concerns are not expected through the next several
The QPF early this week is likely to be too spotty and low to
significantly impact local river stages.
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 68 48 70 48 73 / 0 10 10 10 20
Panama City 67 53 70 57 72 / 0 10 10 10 30
Dothan 65 47 70 50 72 / 0 10 10 20 30
Albany 64 46 69 49 71 / 0 10 10 10 20
Valdosta 64 48 69 47 73 / 0 10 10 10 20
Cross City 69 50 71 48 74 / 0 0 10 0 10
Apalachicola 67 52 69 56 71 / 10 10 10 10 20
Short Term/FIRE WX...Godsey
REST OF DISCUSSION...Block