Special Marine Warning 200, NWS Tallahassee, FL

Area Forecast Discussion
National Weather Service Tallahassee FL
215 PM EDT Mon Jun 28 2021

.NEAR TERM [Through Tuesday]...

A weak upper level low centered near the Florida Big Bend will drift
slowly westward during this period and be centered near Mobile by
tomorrow afternoon. Meanwhile, TD 4 will make landfall along the
South Carolina coast this evening, possibly as TS Danny. This system
is small and will have little impact on our forecast area, except
for isolated to scattered gusty showers across our northern counties
in Georgia overnight. We will be in a more favorable scenario for
convection tomorrow being on the back side of the retreating upper
low. This should enhance forcing for ascent while the 1000-700 mb
mean vector wind veers to southeasterly. PoPs for tomorrow were
generally a blend of the NBM and ECAM.

.SHORT TERM [Tuesday Night Through Wednesday Night]...

The official NHC forecast takes Tropical Depression 4 into the
Tennessee Valley and dissipates it Tuesday evening. In its wake,
the region will be within a moderate easterly low to mid-level
flow. With a weak pressure gradient in place, expect the typical
sea-breeze convection to get underway on Wednesday. Adjusted
PoPs away from NBM and closer to what we would expect given the
flow regime, up to 60 pct from the Southeast FL Big Bend west
along I-10 into Southeast Alabama, given Precipitable Water
above climo. There is the potential for a couple wind gusts of
40+ mph w/storms on Wednesday given enhanced downdraft potential.

.LONG TERM [Thursday Through Monday]...

The pattern transitions on Thursday to a moderate to strong low
to mid-level southwest flow, as a low closing off in the Ohio
Valley sends a "cold" front into the Southeast US. While this
is not expected to change our air mass notably (most likely
dissipating as it approaches the area), it will increase the
chances for showers and thunderstorms to above climo. PoPs are
generally forecast 50-70 pct each day through early next week.

The main concerns this weekend into early next week will be
the potential for heavy rainfall, isolated severe weather, and
an increasing rip current threat for all of the gulf beaches.

Given the approach of the front and anomalously moist air mass,
heavy rainfall is a concern beginning Saturday and continuing
through Monday. Instability is questionable given considerable
cloud cover, but the wind field aloft is modeled unseasonably
strong, so a marginal severe weather threat is possible.

As southwest winds increase along the coast, surf is expected
to build, enhancing the rip current threat as early as Friday,
with the potential for a high risk during the Fourth of July
weekend. While confidence is very low at this time range, this
will be closely monitored given the major holiday weekend.

&&

.AVIATION...
[Through 18Z Tuesday]

VFR conditions will prevail through most of the TAF period once
initial MVFR lifts. Shower and thunderstorm coverage will be low
overall and probabilities were too low at most sites to warrant
mention in the TAF for now. If a thunderstorm occurs at the
terminal, MVFR conditions would be most likely. Thunderstorm
coverage will increase tomorrow afternoon, after this TAF period.

&&

.MARINE...

Easterly winds will veer to southerly on Thursday and southwesterly
on Friday, around 15 knots at times through the period. This will
keep seas elevated, ranging from 1 to 3 feet in Apalachee Bay and
2 to 4 feet elsewhere. Showers and thunderstorm chances will be
greatest on Thursday, Friday, and Saturday.

&&

.FIRE WEATHER...

Scattered showers and thunderstorms and typical summer humidity
levels will preclude most fire weather concerns. The lone exception
is low dispersion indices that are anticipated on Wednesday.

&&

.HYDROLOGY...
The heavy rainfall associated with Tropical Depression 4 will remain
northeast of the area, within the WPC Marginal Risk for Excessive
Rainfall. Otherwise, sea-breeze convection will augment precipitation
until the approach of a "cold" front this weekend into early next
week. Deterministic precipitation totals over the next seven days
are forecast to range from 1.5 to 2 inches over Southeast AL into the
western FL Panhandle, and near the FL Big Bend coast. Elsewhere,
amounts around 1 to 1.5 inches are forecast. With the approach of
the front, there is upside potential to the precip amounts northwest
of the FL Big Bend, where isolated amounts up to 4 inches are
possible. At this time, the main concern would be nuisance flooding.
For the Rivers, the Choctawhatchee at Bruce is currently in action
stage, and forecast to drop below this on Thursday.

&&

.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   71  90  72  88  71 /  10  50  40  40  40
Panama City   72  87  73  85  73 /  10  60  30  60  10
Dothan        69  89  71  88  70 /  10  60  30  60  10
Albany        71  92  73  91  72 /  30  40  30  30  20
Valdosta      69  92  71  89  70 /  10  40  30  50  30
Cross City    72  91  71  88  71 /  10  70  50  60  50
Apalachicola  74  85  75  83  74 /  10  50  30  30  40

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&

NEAR TERM...Wool
SHORT TERM...LF
LONG TERM...LF
AVIATION...Wool
MARINE...LF
FIRE WEATHER...Wool
HYDROLOGY...LF