Severe Thunderstorm Warning 154, NWS Tallahassee, FL

Area Forecast Discussion
National Weather Service Tallahassee FL
146 PM EDT Sun Jul 22 2018

.AVIATION [Through 18Z Monday]...
Thunderstorms with strong winds and hail have the potential to
impact area terminals this afternoon, especially KDHN, KECP,and
KTLH. Activity should diminish from west to east after dark, with
VFR conditions expected to prevail overnight.

&&

.PREV DISCUSSION [1029 AM EDT]...

.NEAR TERM [Through Today]...

The unusual pattern continues with a deep trough over the eastern
CONUS with several +PV anomalies propagating through it today.
These anomalies will help increase divergence and cool air aloft,
both of which will help maintain a very unstable environment. The
12Z TAE sounding showed an astounding 4369 J/kg SBCAPE, which
beats the previous daily max (3468 J/kg) by just over 900 J/kg! To
our north, a surface "cold" front is draped across central AL and
GA. As vorticity anomalies swing through the upper level pattern
in the late morning to early afternoon hours, we expect convection
to start kicking off across the tri-state area south of the
approaching front. Convection will then become reinvigorated
later in the afternoon as the north FL seabreeze moves inland.
Although the front will continue to push south towards our area,
it will likely stall out either over us or just to our north, so
storms will likely continue into the overnight hours.

Similar to yesterday, models show SBCAPE will remain in the
4000-6000 J/kg range through the day (and possibly even into the
evening hours) for all but our northernmost counties. Likewise,
deep layer shear will be as impressive as yesterday at around
30-45 kts. Therefore, storms that develop today could be just as
potent today as they were yesterday, perhaps moreso. The majority
of the area is under a slight risk for today. Damaging straight-
line winds and large hails will be the main threats, but an
isolated tornado cannot be ruled out. These storms will also
produce heavy rainfall which could cause localized flooding and
perhaps wash out dirt roads.

.SHORT TERM [Tonight Through Tuesday]...

In the upper levels a deep trough will be over the Southeast. At the
surface a low over Tennessee will bring a cold front through the
region Monday morning. Then a weak low will remain over the
Southeast through Tuesday. PW values will briefly go down as the
cold front passes. However PW values will likely rebound back to
near 2 inches Monday afternoon as wrap around moisture moves in.
POPs will be high tonight as the front moves through and again
Monday/Tuesday afternoon and evening.

Severe storms remain possible tonight until the cold front moves
through. Ahead of the front deep layer shear will be 40 to 50 knots
and CAPE could be as high as 4000 J/KG or so even a few hours after
sunset. Scattered to numerous showers and thunderstorms are expected
Monday and Tuesday as wrap around moisture moves in from the north
on Monday and southerly flow returns on Tuesday.

Highs will be near 90. Lows will be in the low 70s.

.LONG TERM [Tuesday Night Through Sunday]...

In the upper levels a trough will be over the Southeast. At the
surface a weak pressure gradient will be in place. Southerly flow
will dominate with high pressure to the east over the Atlantic. The
wet pattern will continue this week and POPs will be high (40 to 60
percent). Highs will be in the low 90s. Lows will be in the low to
mid 70s.

.MARINE...

Westerly winds are increasing this morning. A Small Craft Advisory
is in effect starting at 5 AM EDT. Winds will become more moderate
after midnight tonight. Seas will be the highest late this afternoon
into the overnight hours. Light to moderate southerly winds will
return on Tuesday.

.FIRE WEATHER...

Red flag conditions will not occur over the next several days with
moisture expected to remain high across the area. High dispersions
are likely this afternoon.

.HYDROLOGY...

The wet pattern continues this week. 0.25 to 2 inches of rain is
predicted through Monday night with the highest totals in the
Florida Big Bend. Locally higher amounts are likely. The heavier
downpours may result in ponding of water on roadways and flooding of
low-lying areas. Over the next week, 1.25 to 4 inches of rain is
forecast with the highest totals expected in the Florida Big Bend.
Most local rivers are steady or slowly rising at this time. Most
local rivers remain below action stage.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is requested. Spotters should safely report
significant weather conditions and/or damage by calling the office or
tweeting us @NWSTallahassee.

&&

.PRELIMINARY POINT TEMPS/POPS...

Tallahassee   73  90  72  89  72 /  50  50  20  60  30
Panama City   78  89  76  87  77 /  50  40  20  50  30
Dothan        72  88  72  87  73 /  30  40  20  60  30
Albany        72  88  72  88  74 /  30  40  20  70  30
Valdosta      71  89  72  88  72 /  40  50  20  70  30
Cross City    74  90  73  87  73 /  70  50  30  60  50
Apalachicola  78  88  76  87  77 /  60  30  20  50  30

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Monday morning for Coastal Bay-
     Coastal Franklin-Coastal Gulf-South Walton.

     Heat Advisory until 6 PM EDT /5 PM CDT/ this evening for Calhoun-
     Central Walton-Coastal Bay-Coastal Franklin-Coastal Gulf-
     Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden-
     Holmes-Inland Bay-Inland Franklin-Inland Gulf-Inland
     Jefferson-Inland Taylor-Inland Wakulla-Jackson-Leon-Liberty-
     North Walton-South Walton-Washington.

GA...None.
AL...None.
GM...Small Craft Advisory until 4 AM EDT Monday 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 Suwannee
     River to Keaton Beach FL out 20 NM-Coastal waters from
     Mexico Beach to Apalachicola FL out 20 NM-Coastal waters
     from Mexico Beach to Okaloosa Walton County Line FL out 20
     NM-Waters from Suwannee River to Apalachicola FL from 20 to
     60 NM-Waters from Apalachicola to Mexico Beach FL from 20
     to 60 NM-Waters from Mexico Beach to Okaloosa Walton County
     Line FL from 20 to 60 NM.

&&

NEAR TERM...Nguyen
SHORT TERM...McD
LONG TERM...McD
AVIATION...Camp
MARINE...McD
FIRE WEATHER...McD
HYDROLOGY...McD