Flash Flooding and Flooding in Florida, August 3 to 23, 2021

Area Forecast Discussion
National Weather Service Tallahassee FL
408 PM EDT Tue Aug 3 2021

.NEAR TERM [Through Wednesday]...

Broad cyclonic flow in the upper levels continues over the region
through the near term period. This broad cyclonic flow, when
combined with plenty of deep-layer moisture in place across the
region, will lead to widespread shower and thunderstorm coverage
through the remainder of tonight and into Wednesday. Flooding rains
will continue to be the main point of concern.

The stable conditions that were in place this morning have since
eroded away as thick low level clouds thinned and diurnal heating
has increased instability across the forecast area. In response,
widespread showers and storms have formed across much of the
Panhandle and Big Bend, with additional development further inland
across our GA/AL counties. Due to very moist conditions in place,
with precipitable waters well above 2 inches, and favorable upper
level support, rain rates will easily hit 2 to 3 inches per hour in
the strongest storms through the remainder of the afternoon. This
threat is greatest across the Florida Panhandle and Florida Big Bend
where the best combination of enhanced convergence along a
stationary frontal boundary and deep-layer moisture exists. Much of
these areas are under a flash flood watch and it was extended into
Wednesday afternoon.

For tonight, expect convection to wind down over inland areas in the
late evening hours as daytime instability lessens and  the frontal
boundary in place slowly drifts back south as stronger northeasterly
flow takes over. With enhanced convergence along this frontal
boundary overnight, and the diffluent flow aloft remaining in
support, expect widespread showers and storms to develop over our
marine zones and coastal zones overnight. The flash flood concerns
will remain in place across the watch area overnight. Given recent
upticks in the potential for heavy rain overnight, with some CAM
guidance indicating the greater probabilities for 6 inches overnight
in some locations, have extended the flash flood watch into
Wednesday afternoon. Widespread rainfall amounts along the FL coast
will likely be around 1 to 3 inches overnight and into Wednesday
afternoon with isolated amounts possibly up to 6 or 8 inches by the
end of Wednesday.

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

The trough currently positioned over eastern CONUS will lift out of
our region throughout the day on Thursday. As the trough lifts out
it will confine the highest PoPs along a narrow corridor that rides
up our easternmost counties from the SE Big Bend up through south
central Georgia. Given the synoptic support, some storms may be
stronger than normal summertime pulse storms. These storms may also
persist into the evening even in the absence of diurnal mechanisms.
In its wake, the trough is expected to leave a stationary boundary
across our region leading to a continued unsettled pattern. Expect
overnight lows in the low 70s with daytime highs in the upper 80s.

.LONG TERM [Friday Through Tuesday]...

Throughout the day on Friday a second, and slightly less amplified,
trough brushes across eastern CONUS. This second trough will then
lift out by Saturday morning taking the stalled stationary boundary
with it. Thus, through Saturday morning we can expect an abundance
of moisture and synoptic forcing leading to above normal
precipitation across the region, which is highlighted in the hydro
section below. Throughout Saturday we will begin to see a ridge
slide westward across our region and with it bringing our PoPs back
into typical summertime ranges associated with afternoon
thunderstorms. We'll be on the western flank of the ridge, which
will provide no relief in terms of decreases in dewpoints through
the rest of the long term as southerly flow remains in place. Models
are currently suggesting a warming up period next week as the ridge
continues to build right over our region. This is something we'll be
on the look out for as heat indices could potentially rise back into
the 105+ degree range. Expect daytime highs in the upper 80s warming
up into the mid 90s with overnight lows in the low to mid 70s.

&&

.AVIATION...
[Through 18Z Wednesday]

VFR conditions should prevail through the remainder of the
afternoon/evening with the only aviation concerns revolving
around scattered showers and thunderstorms developing. Overnight,
northeast flow will likely develop along with widespread IFR/LIFR
conditions, especially across inland terminals at DHN, VLD, and
ABY. Less of a chance for these restrictions at TLH, ECP, but
confidence is high enough to mention in TAF. Widespread showers
and storms are expected again tomorrow, beginning in FL terminals
and moving north through the day.

&&

.MARINE...

Winds and seas will gradually diminish through the week becoming
light over the upcoming weekend along with low seas as high pressure
builds into the region.

&&

.FIRE WEATHER...

Fire weather concerns are low the next few days with moist and wet
conditions expected

&&

.HYDROLOGY...

The wet pattern continues and some locations across the tri-state
region have already received several inches of rain since Sunday.
The best prospects for heavy rain tonight will likely be along the
coastal areas of the Florida Panhandle, the Florida Florida Big
Bend, and the area in and around Valdosta where additional
widespread amounts of 2 to 4 inches are possible with isolated
amounts up to 5 inches. A Flash Flood watch has been issued for
those Florida areas through Wednesday afternoon. These amounts could
cause localized increases on area rivers, especially on faster
responding creeks. Isolated flash flooding is also possible due to
high rain rates and the potential for training storms in this
pattern. Significant river flooding through this event is not
anticipated, but a few rises on rivers, especially in our eastern
basins, are a possibility. Basins to watch over the next 7 to 10
days for increased flooding potential will be the Ochlockonee,
Withlacoochee Basin, and the Suwanee Basin (especially if the higher
end amounts fall over this basin).

&&

.SPOTTER INFORMATION STATEMENT...

Spotter activation is requested. Spotters should safely report
significant weather conditions and/or damage (while following all
local, state, and CDC guidelines) by calling the office or tweeting
us @NWSTallahassee.

&&

.PRELIMINARY POINT TEMPS/POPS...

Tallahassee   73  84  73  89  73 /  50  70  40  50  30
Panama City   74  86  74  90  75 /  50  70  30  30  20
Dothan        71  86  70  89  71 /  40  50  20  20  10
Albany        72  86  71  88  72 /  40  50  30  30  10
Valdosta      72  83  71  86  72 /  50  70  40  60  20
Cross City    74  83  74  86  74 /  60  90  60  70  40
Apalachicola  75  84  75  87  76 /  60  80  50  50  40

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Flash Flood Watch through Wednesday afternoon for Calhoun-
     Coastal Bay-Coastal Dixie-Coastal Franklin-Coastal Gulf-
     Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Inland Bay-
     Inland Dixie-Inland Franklin-Inland Gulf-Inland Jefferson-
     Inland Taylor-Inland Wakulla-Lafayette-Leon-Liberty-Madison.

     High Rip Current Risk until 3 AM EDT /2 AM CDT/ Wednesday for
     Coastal Bay-Coastal Franklin-Coastal Gulf-South Walton.

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

NEAR TERM...Dobbs
SHORT TERM...Oliver
LONG TERM...Oliver
AVIATION...Dobbs
MARINE...Oliver
FIRE WEATHER...Dobbs
HYDROLOGY...Oliver

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
158 PM EDT TUE AUG 3 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1228 PM     FLOOD            SUWANNEE                29.33N 83.14W
08/03/2021                   DIXIE              FL   PUBLIC

            MPING REPORT: RIVER/CREEK OVERFLOWING;
            CROPLAND/YARD/BASEMENT FLOODING.

&&

IG3

Special Weather Statement
National Weather Service Tallahassee FL
451 PM EDT Tue Aug 3 2021

FLZ118-127-128-032130-
Coastal Wakulla FL-Coastal Jefferson FL-Coastal Taylor FL-
451 PM EDT Tue Aug 3 2021

...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL WAKULLA...
SOUTHWESTERN JEFFERSON AND WEST CENTRAL TAYLOR COUNTIES UNTIL 530 PM
EDT...

At 450 PM EDT, Doppler radar was tracking a strong thunderstorm 11
miles east of St. Marks, moving southeast at 20 mph.

Winds in excess of 40 mph will be possible with this storm.

This storm will remain over mainly rural areas of east central
Wakulla, southwestern Jefferson and west central Taylor Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3010 8415 3019 8408 3007 8378 3004 8371
      2991 8380
TIME...MOT...LOC 2050Z 292DEG 19KT 3010 8404

01-GONZALEZ