Area Forecast Discussion
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FXUS62 KTAE 191144

Area Forecast Discussion
National Weather Service Tallahassee FL
644 AM EST Thu Jan 19 2017

.AVIATION [Through 12Z Friday]...

Dense fog has spread across much of the region this morning with
VLIFR conditions at all terminals except ABY. VFR is expected by
late morning/early afternoon. Some showers are possible across the
far western TAFs (DHN and ECP) during the afternoon with rain and
TSTMs increasing from west to east across the sites late this
evening and overnight tonight.



.NEAR TERM [Through Today]...

Dense fog is in place across Florida and starting to see this expand
into southern Georgia and southeast Alabama. A dense fog advisory is
in effect for much of the area through late morning.

The upper level ridge over the southeast will shift eastward today
as a shortwave tracks across the Midwest. As this occurs, the upper
level winds become more southwest, increasing the deep layer
moisture across the CWA. A few showers and isolated thunderstorms
are possible across the western half of the CWA this afternoon
however instability is limited to 500 J/kg or less and overall
coverage of convection will be limited. Hi-res models are in good
agreement that the bulk of the convection should hold off until
after 00z and at that point, precipitation chances greatly increase.

High temperatures will once again be above normal with highs in the
mid to upper 70s across much of the CWA and upper 60s to lower 70s
along the coast.

.SHORT TERM [Tonight Through Saturday]...

Widespread convection will spread eastward across our region tonight
into Friday morning. SPC has highlighted our western zones for a
marginal risk of severe weather with this activity mainly for this
evening. The limiting factor will be lack of sufficient instability
and the severe threat will diminish during the overnight hours. Rain
chances will taper off significantly on Friday as the deep layer
moisture and upper support pass to our east. This will be short
lived as another round of rain and thunderstorms develop associated
with the next shortwave that will impact our region Friday night
through Saturday. The 700-500 mb lapse rates may steepen to around
7C/km on Saturday with increasing instability. Some severe weather
cannot be ruled out on Saturday with the possibility of hail as one
of the threats.

.LONG TERM [Saturday Night Through Thursday]...

While the first two impulses to impact our region bring with them
the potential for severe weather, it is the next one that is
scheduled to arrive Saturday night into Sunday that is the most
concerning. Both the GFS and ECMWF continue to show a deep low
pressure system developing over the Southern Plains and moving
eastward into the southeastern states on Sunday. The low level jet
is forecast to intensify (40-50kts) across the area with a deepening
surface low. The global models continue to differ on the
evolution of the mesoscale features with the EURO the most
aggressive showing a deepening surface low moving from southeast
Alabama to the Central Savannah River area on Sunday. However,
both models show sufficient instability and shear for a threat of
severe storms on Saturday night and Sunday with this system.
Significant severe storms, including the threat of some tornadoes,
cannot be ruled out.

After Sunday, the system pulls away from the area with a drying
trend for at least a few days. Temperatures will remain well above
average until the main system moves through on Sunday, then a
cooler, more seasonal airmass is expected to start next week.


Rain and thunderstorm chances will increase starting tonight and
continue through the weekend with multiple disturbances affecting
the marine area. A strong cold front is expected to move through
the local waters Sunday into Monday with gusts to gale force
expected and seas in excess of 10 feet. Some thunderstorms could
also be strong to severe, especially this weekend.


Winds will be elevated at times through the weekend however with RH
values above critical thresholds, ERC values and high chances of
wetting rain through the weekend, there are no fire weather


Multiple rounds of rain are expected over the next several days.
The heaviest rounds of rain are likely to arrive on Saturday and
Sunday. Total widespread amounts through Monday are expected to be
in the 2-4 inch range, but there will likely be localized areas
that see higher amounts. Ultimately, the greatest threat for any
flooding will come at the end of the event on Saturday night or
Sunday and will depend on how much rain has fallen from the
previous rounds. The flooding potential will need to be monitored
closely over the next several days, but the magnitude of the flood
threat remains pretty uncertain at this point. The MMEFS data does
show a few river basins with a chance to reach flood stage. Some
basins to watch include the Kinchafoonee Creek, Choctawhatchee
River, and Chipola River. There may also be a minor coastal flood
threat along Apalachee Bay depending on the timing of the
strongest winds with the tide cycle. The 12z ESTOFS is showing the
potential for around 3 feet of storm surge in Apalachee Bay given
the strong wind field associated with the low pressure system.
This could conceivably cause some minor coastal flooding if it
lines up with a high tide cycle.



Tallahassee   76  61  79  64  76 /  20  60  30  30  80
Panama City   71  63  75  65  75 /  40  80  30  50  80
Dothan        77  60  79  62  76 /  40 100  30  50  80
Albany        77  59  79  63  76 /  20  90  30  30  80
Valdosta      77  60  78  64  77 /  10  50  30  20  80
Cross City    78  58  79  64  77 /  10  40  20  20  60
Apalachicola  71  64  76  66  74 /  30  50  30  40  80



FL...Dense Fog Advisory until 11 AM EST /10 AM CST/ this morning for
     Calhoun-Central Walton-Coastal Bay-Coastal Dixie-Coastal
     Franklin-Coastal Gulf-Coastal Jefferson-Coastal Taylor-
     Coastal Wakulla-Gadsden-Holmes-Inland Bay-Inland Dixie-
     Inland Franklin-Inland Gulf-Inland Jefferson-Inland Taylor-
     Inland Wakulla-Jackson-Lafayette-Leon-Liberty-Madison-North
     Walton-South Walton-Washington.

GA...Dense Fog Advisory until 11 AM EST this morning for Baker-Brooks-

AL...Dense Fog Advisory until 10 AM CST this morning for Coffee-Dale-

GM...Dense Fog Advisory until 11 AM EST this morning for Apalachee
     Bay or Coastal Waters From Keaton Beach to Ochlockonee
     River Fl out to 20 Nm-Coastal Waters From Ochlockonee River
     to Apalachicola Fl out to 20 Nm-Coastal waters from
     Apalachicola to Destin FL out 20 NM.



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