Tornado Warning 46, NWS Tallahassee, FL

Area Forecast Discussion
National Weather Service Tallahassee FL
151 PM EDT Sat Aug 22 2020

.AVIATION...
[Through 18Z Sunday]

Much of the rainfall today will be located from TLH to VLD and
eastward. Low confidence west of this line. Coverage will decrease
this evening with a lull overnight. Gulf water showers will
develop overnight, possibly reaching coastal Florida sections
towards dawn then spreading inland in the morning hours.

&&

.PREV DISCUSSION [1122 AM EDT]...

.NEAR TERM [Through Tonight]...

A large upper level trough, which has dominated the weather pattern
over the local area will begin to break down through the day as a
large upper level ridge builds in from the east. As the periphery of
this ridge noses in from the east, deep southerly flow will grow in
strength and bring plenty of moisture into the region. It will
likely be an early start to showers and thunderstorms with
widespread storms, especially east of Tallahassee in the plume of
higher precipitable waters. Slightly drier conditions can be
expected west of Tallahassee where deep layer moisture won't be as
prevalent, but still plenty supportive for scattered showers and
storms. Only uncertainty in the forecast through the evening period
will depend on how much convection we have in the morning hours.
Most recent hi-res guidance keeps things a little more quiet in
the afternoon periods as widespread showers and storms keeps
conditions cloudy and limits instability in the later part of the
day. With this mind, lowered POPs for later in the day. High
temperatures continue to remain in the low to mid 80s with
widespread clouds expected, especially across the FL Big Bend and
southern GA. Main worries today revolve around heavy rain as
preciptable water content is well over 2 inches and any training
convection will easily drop a quick 2 inches of rain. Potentially
leading to isolated flooding.

Similar to recent nights, we're expecting another round of
overnight/early morning convection to develop early Sunday morning
as deep layer moisture remains high across the region.

.SHORT TERM [Sunday Through Monday]...

A strong, Atlantic subtropical ridge builds westward over FL to
begin next week, causing winds to turn more easterly. The western
periphery of this ridge, combined with the outflow of Tropical Storm
Marco (near or over the Yucatan) is forecast to bring a plume a
moisture across our area. Therefore, PoPs are high through the short-
term period, with widespread precipitation expected during the
afternoon hours when instability is greatest. Rain chances taper off
in the northeast half of our CWA after sunset, but remain elevated
over our coastal/marine areas as the aforementioned moisture plume
advects northwest.

Given a moist airmass in place and high instability, isolated strong
(or even briefly severe) thunderstorms cannot be ruled out, with
some being effective rainmakers. In fact, WPC places coastal FL
(extending from Franklin to Walton County) under a marginal risk for
excessive rainfall for Sun into Mon. The flipside of a continued wet
pattern is lower daytime high temperatures, which are forecast to
range from the mid 80s where rain persists, to low 90s where there
is less convective coverage. Low temperatures are expected to be in
the low 70s.

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

Uncertainty looms for the long-term period as the forecast will
mainly be dictated by the evolution of Tropical Storm Laura. As of
2am EDT, the center of Laura was approaching the Virgin Islands. It
is expected to move across much of the Greater Antilles this weekend
along the southern periphery of the aforementioned subtropical
ridge. The official NHC forecast calls for the storm to emerge into
the Gulf of Mexico late Mon, and turn more to the northwest into the
central Gulf on Tues as it rounds the western periphery of the
ridge. Confidence in the forecast is low at this time, mainly
because of the disorganized nature of Laura and likely interaction
with the mountainous terrain of the Caribbean islands. Currently,
our CWA is not within the forecast cone, but the high uncertainty
will likely necessitate minor forecast track changes over the next
couple of days. Regardless, users are urged not to focus on the
exact track as impacts can occur outside the cone. Assuming Laura
remains intact by early next week, the very warm Gulf waters
should allow Laura to at least gradually strengthen before making
landfall as a possible hurricane along the northern Gulf coast.

Outside of dangerous beach/marine conditions and heavy rainfall
potential, it is still too early to determine specific impacts to
our area. Highest PoPs of the period are Tues and Wed when Laura
makes its approach to the northern Gulf coast. Tropical Storm
conditions are possible along the immediate coast of Walton, and
portions of Bay/Gulf County on Wed. Rain chances return to more
climatological values Thurs and Fri as ridging combined with diurnal
convection influence the local weather. High temperatures are
expected to be in the low 90s, with lows in the low/mid 70s (except
along the immediate coast).

.MARINE...

Winds and seas will remain elevated through much of the period.
For the weekend, unsettled conditions expected with widespread
showers and storms, especially in the overnight hours. Southerly
flow around 10 to 15 knots expected today with seas around 3 feet.
By the end the weekend, stronger easterly flow begins to move in
with winds and seas expected to be in cautionary levels through the
beginning of next week. Marine conditions continue to worsen through
mid week as southerly swell from Tropical storm Marco moves in, and
Tropical Storm Laura nears our area waters Tuesday into Wednesday.
Tropical storm conditions are possible Tuesday and Wednesday,
especially in waters west of Apalachicola. Forecast uncertainty
remains high with Laura so be on the lookout for future updates as
next week nears.

.FIRE WEATHER...

Other than low afternoon dispersions generally east of Apalachicola
River on Sat and areawide on Sun, there are no fire weather concerns
over the next several days, as a wet pattern will be in place, with east
to southeast winds.

.HYDROLOGY...

A wet pattern remains in place over the next several days, with
Tropical Storm Laura possibly enhancing rainfall potential early
next week. The 7-Day QPF places the heaviest amounts (3-6 inches) in
the western Panhandle and generally 1-3 inches elsewhere. Locally
heavier amounts are possible and are subject to change with time, as
they will be dependent on Laura's structure, track, and intensity.
Prior to the tropical storm's approach, there are isolated flood
concerns from coastal Franklin to coastal Walton County Sun into
Mon where a marginal risk for excessive rainfall is highlighted
in those areas, per WPC.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur (while following all local, state, and CDC guidelines) by
calling the office or tweeting us @NWSTallahassee.

&&

.PRELIMINARY POINT TEMPS/POPS...

Tallahassee   74  85  75  91  77 /  40  70  30  70  40
Panama City   76  85  77  88  79 /  50  80  50  70  50
Dothan        71  86  73  87  76 /  40  70  20  60  20
Albany        72  86  75  89  77 /  30  60  20  60  20
Valdosta      73  84  75  89  76 /  30  60  10  80  20
Cross City    75  87  75  91  77 /  40  70  20  80  40
Apalachicola  78  85  78  88  79 /  50  80  50  70  60

&&

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

GA...None.
AL...None.
GM...None.
&&

NEAR TERM...Dobbs
SHORT TERM...IG3
LONG TERM...IG3
AVIATION...Scholl
MARINE...Dobbs
FIRE WEATHER...IG3
HYDROLOGY...IG3