Severe Thunderstorm Warning 1, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
355 AM EST Sat Jan 11 2014

...A Slight Risk for Severe Thunderstorms Today...

.Near Term [Through Today]...
Widespread dense fog continues across the Florida Big bend early
this morning and a dense fog advisory continues in effect there,
while it has been lifted elsewhere. We expect visibilities to
improve across the Big Bend by 14z as the fog lifts with surface
winds increasing ahead of a cold front. However, the low level
cloudiness should linger through the day with little if any
sunshine. Widespread showers and isolated thunderstorms will sweep
through the local region in advance of the front and we feel
confident enough to raise PoPs to nearly 100 percent for all
zones. The SPC continues to highlight our CWA in the day one
convective outlook for a slight risk of severe thunderstorms with
the main concern being damaging winds although an isolated tornado
can't be ruled out. While low level vertical sheer profiles look
impressive, the best dynamics and stronger low level jet should be
displaced off to our northeast. However, the primary limiting
factor will be marginal instability at best. As mentioned, the
local region should stay socked in with low level clouds through
the day limiting destabilization. The locally run CAM models show
a very low end threat for severe weather for our FA. However,
we included isolated severe thunderstorms in the grids for all
zones due to the low-end threat. We expect fairly widespread
1-inch rainfall amounts with this system before all is said and
done tonight. Despite the clouds and rain, we should see max
temps in the mid to upper 70s.

.Short Term [Tonight Through Monday]...
The upper level pattern will remain progressive across the region
with one trough exiting east of the area tonight and another
reaching the Lower Mississippi Valley by Tuesday evening. The cold
front should exit southeast of the Lower Suwannee by 02-03z. We have
included slight to low chance PoPs roughly along and east of the
Aucilla and Withlacoochee Rivers. High pressure will then build east
along the Gulf Coast on Sunday clearing skies. Temperatures will be
cooler behind the front, but remain a few degrees above normal with
morning lows in the upper 30s to mid 40s and afternoon highs
generally in the mid 60s. The high will move off the Southeast U.S.
coast on Monday with return flow returning increasing moisture off
the Gulf of Mexico. High temps will reach the upper 60s in most
areas with lower 70s in the eastern FL Big Bend. As the next frontal
system approaches, rain chances will return to the forecast with
likely PoPs far west and chance PoPs elsewhere. With so little time
between fronts, we do expect sufficient instability to become
established to mention thunder anywhere except over the marine area
on Monday at this time.

.Long Term [Monday Night Through Saturday]...
Very little change from our previous fcst over the extended period,
as the mean trough will remain entrenched over the eastern half of
the U.S. throughout the period. This will allow a series of
shortwaves to dig southeastward into our region and reinforce the
main trough, which should result in a lengthy period of below
climo (but not extreme) temps beginning on Tuesday. While the
first in this series of shortwaves will be very active with
numerous showers and thunderstorms ending by Tuesday morning, the
remaining ones are expected to be dry, and only serve to reinforce
the cool to potentially cold temperatures, especially as indicated
by the ECMWF.

&&

.Aviation...
[Through 06Z Sunday] LIFR conditions to continue at all sites at
least through daybreak. After that, conditions will only gradually
improve as rain moves in from west to east and surface winds
increase ahead of a cold front. As rain and storms move through
the area in the late morning and afternoon on Saturday, expect IFR
conditions. Conditions should return to VFR at DHN/ECP around 20z
and finally VLD around 23z with west to northwest winds up to 15
knots.

&&

.Marine...
Sea fog is expected to continue over the cooler shelf waters east
of Apalachicola through the morning and possibly into the
afternoon. Southerly winds will increase today ahead of an
approaching cold front. At this time, we expect winds and seas to
peak mainly at cautionary levels, although a brief period of
marginal advisory conditions cannot be ruled out. Winds will shift
to the west behind the front which will enter the western waters
this morning an exit east of the area this evening. Winds will
then become northwest overnight possibly reaching cautionary
levels once again. High pressure will build east Sunday through
Monday with winds becoming light and veering to onshore by Sunday
night. The next front will cross the waters Monday night into
Tuesday morning. Winds will once again reach cautionary to
marginal advisory criteria ahead of and behind this boundary. A
third front will sweep quickly across the waters Tuesday night.
Seas and offshore winds behind this front are likely to reach
advisory levels.

&&

.Fire Weather...
After a wet day today, much drier conditions are expected on Sunday
in the wake of a cold front but red flag conditions are not expected.
Rain returns to the region on Monday.

&&

.Hydrology...
Rainfall totals with today's frontal system will generally range
from about an inch and a half in Walton County to 3/4 of an inch in
Dixie with most areas in between around an inch. Another system on
Monday and Monday night is expected to produce roughly a half to 3/4
of an inch. While these events should cause minor rises on some area
rivers, flooding is not expected at this time.

&&

.Preliminary Point Temps/PoPs...

Tallahassee   76  42  65  40  69 /  90  10   0   0  40
Panama City   75  46  64  48  67 / 100   0   0   0  60
Dothan        73  41  63  43  67 / 100   0   0   0  50
Albany        75  41  64  40  67 / 100  10   0   0  40
Valdosta      77  44  64  40  69 / 100  20   0   0  30
Cross City    77  46  67  38  72 / 100  30   0   0  30
Apalachicola  75  46  62  47  66 /  90  10   0   0  50

&&

.TAE Watches/Warnings/Advisories...

FL...Dense Fog Advisory until 9 AM EST this morning for Coastal
     Dixie-Coastal Franklin-Coastal Jefferson-Coastal Taylor-
     Coastal Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland
     Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon-
     Liberty-Madison.
GA...None.
AL...None.
GM...Dense Fog Advisory until 4 PM EST this afternoon for Apalachee
     Bay-Coastal waters From Ochlockonee River to Apalachicola FL
     out to 20 NM-Coastal waters from Suwannee River to Keaton
     Beach FL out 20 NM-Waters from Suwannee River to Apalachicola
     FL from 20 to 60 NM.

&&

NEAR TERM...BARRY
SHORT TERM...WOOL
LONG TERM...GOULD
AVIATION...BARRY
MARINE...WOOL
FIRE WEATHER...BARRY
HYDROLOGY...WOOL