Special Weather Statement, NWS Jacksonville, FL

Area Forecast Discussion
National Weather Service Jacksonville FL
320 PM EDT Tue Aug 24 2021

.NEAR TERM [Through Tonight]...

Late morning surface analysis depicted a rather stagnant weather
pattern locally, as Atlantic high pressure (1022 millibars)
remains centered near Bermuda and was extending its axis
southwestward across the FL peninsula. Meanwhile, a narrow deep-
layered trough continues to extend from Henri's remnants from
the Canadian Maritime region south-southwestward to the Georgia
coastal waters and along the Interstate 10 corridor in northeast
FL and the Suwannee Valley. Otherwise, ridges aloft remain
centered over eastern Texas and the lower Mississippi Valley and
also near Bermuda, while a Tropical Upper Tropospheric Trough
(TUTT) was spinning westward beneath this ridge towards the
Bahamas. Latest RAP/LAPS analyses indicate that deep tropical
moisture remains in place locally, with PWAT values around or
above 2 inches region-wide, with rather significant surface-based
CAPE values above 3,000 j/kg already in place all along the I-10,
while lower values were in place for locations north of Waycross
and also across north central FL, where cloud cover was thicker
this morning. Scattered convection was already developing late
this morning along the trough axis from coastal southeast GA
southwestward to the Suwannee Valley, with activity generally
moving slowly eastward. Temperatures at 15Z were rising through
the mid 80s, except around 80 for locations north of Waycross,
where stratus has been slower to thin out. Dewpoints remain in the
muggy mid to upper 70s at most locations.

The base of the narrow trough aloft will slowly pivot southward
across our region this afternoon and evening, resulting in
numerous showers and thunderstorms developing almost area-wide
through the early evening hours. Latest short-term, high
resolution guidance indicates that convection currently developing
over southeast GA will increase in coverage as it expands
southward, with the Gulf coast sea breeze then pushing activity
towards the I-95 corridor in northeast FL later this afternoon
through early this evening. Northward moving convective outflows
may also generate convection later this afternoon for locations
near the Altamaha, Ocmulgee and Alapaha Rivers that are currently
more stable due to early morning fog and stratus. Cell mergers and
mesoscale boundary collisions may result in pulsing convection
through early this evening, with stronger storms capable of
producing downburst wind gusts up to 50 mph and frequent lightning
strikes. However, localized flooding is likely the primary hazard
due to slow moving convection, with urban and typically flood
prone low lying areas being the most threatened by tropical and
possibly training downpours. Widespread convection and cloud cover
should keep highs mostly in the 85-90 degree range, with a few
lower 90s possible along the I-75 and I-10 corridors, where
sunshine has been more plentiful thus far.

Convection may linger through the early to mid evening hours
tonight as base of the narrow trough pivots eastward over our
adjacent Atlantic waters. Additional shallow convection could also
develop along the I-10 corridor during the predawn hours as deep
tropical moisture remains in place ahead of the approaching TUTT
feature from the southeast. Lows will mostly fall to the low and
mid 70s.

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

The aforementioned TUTT will slide north-northwest towards the
Florida Big Bend over the next couple days with persistent
easterly onshore flow at the lower and mid levels. Forcing will be
weak, but between an east coast sea-breeze in the afternoon, the
lingering trough across SE GA, there should be at least scattered
if not numerous showers and thunderstorms Wednesday from the early
afternoon into the evening. A swath of drier air (PWATs around
1.4-1.8 inches) will brush the area Wednesday night and Thursday
morning, then those 1.8 to 2.2 inch PWATs will return from
southeast to northwest across the area on Thursday afternoon.
Scattered to numerous afternoon showers and thunderstorms once
again across the area Thursday afternoon, lingering along the
coastline through the night Thursday night.

.LONG TERM [Friday Through Tuesday]...

Persistent south-southeasterly from the low to mid levels will
continue for the next several days. There is some model
discrepancy in regards to tropical development in the southern
Gulf waters that may approach anywhere from south TX to southern
LA by the weekend. The further west this feature tracks, the more
likely we'll have a drier pattern for the weekend. On the flip
side, the further northeast the disturbance track, the more
tropical moisture will be on tap for the region. Model trend has
been closer to the latter, so leaning towards the wetter pattern
continuing through at least Saturday. Deep layer ridging will
build over the region early next week, bringing with it subsidence
and thus lower chances for storms.

&&

.AVIATION...
[Through 18Z Wednesday]

IFR visibilities are expected through around 19Z at GNV as slow
moving thunderstorms impact the terminal. MVFR conditions will
likely prevail at SSI through at least 19Z. Showers and
thunderstorms will likely overspread the Duval County terminals
and SGJ through the mid to late afternoon hours, and we included
TEMPO groups for briefly gusty winds and IFR visibilities during
heavier downpours through around 23Z at these terminals.
Conditions will likely improve to VFR at SSI and GNV towards 21Z.
Activity could linger through the early evening hours at SGJ.
Outside of thunderstorm activity, southerly surface winds will
remain sustained around 10 knots at the inland terminals through
around 23Z, while the Atlantic sea breeze situated just inland
from the coastal terminals results in southeasterly surface winds
sustained at 10-15 knots at SGJ and SSI. Southerly surface winds
will then decrease to around 5 knots or less at the inland
terminals after 01Z, with sustained speeds remaining at 5-10 knots
overnight at the coastal terminals. Periods of MVFR to IFR
visibilities will be possible overnight at VQQ and possibly GNV.

&&

.MARINE...

Southerly winds today will shift to become more southeasterly and
then easterly the next few days as an inverted trough drifts
westward, nudging the Bermuda high to the north and west. This
onshore flow will keep scattered to numerous showers and
thunderstorms in the forecast for the next several days. When the
trough makes its closest approach to our offshore waters
Wednesday and Thursday, offshore winds will increase to around 15
knots, possibly 15 to 20 knots and seas will increase to around 5
to 7 feet.

Rip Currents: Low risk of rip currents today and Wednesday,
increasing Thursday and Friday.

&&

.FIRE WEATHER...

Scattered to numerous showers and thunderstorms the next several
days, with heavy rainfall possible each afternoon. Gusty winds and
localized flooding will be the main concern for storms. This wet
pattern, along with light winds in place, will prevent us from
reaching red flag criteria for the next several days.

&&

.HYDROLOGY...

Minor river flooding will continue along upper portions of the
Suwannee, along lower portions of the Santa Fe and also for the
lower Suwannee River south of the confluence with the Santa Fe
through at least late this week, as most river gauges are slowly
falling or nearly steady.

Widespread 1 to 3 inches of rain is expected to accumulate over
the area over the next few days, with isolated totals closer to 3
to 5 inches. The highest accumulations are generally anticipated
along the I-95 corridor. This could lead to localized flooding.

&&

.PRELIMINARY POINT TEMPS/POPS...

AMG  71  87  72  87  71 /  40  50  20  30  20
SSI  76  87  78  87  77 /  60  70  20  50  50
JAX  73  89  75  88  75 /  40  40  20  60  50
SGJ  74  88  77  86  75 /  40  30  30  70  50
GNV  72  89  73  88  73 /  40  40  20  60  20
OCF  73  90  73  88  73 /  50  40  20  70  20

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&

Special Weather Statement
National Weather Service Jacksonville FL
310 PM EDT Tue Aug 24 2021

FLZ340-241945-
Western Marion FL-
310 PM EDT Tue Aug 24 2021

...A strong thunderstorm will impact portions of southwestern Marion
County through 345 PM EDT...

At 309 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles north of Beverly Hills, moving northeast at 20 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Rainbow Lakes Estates, Dunnellon and Romeo.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

&&

LAT...LON 2897 8232 2900 8237 2901 8239 2902 8240
      2902 8242 2905 8247 2905 8249 2904 8250
      2904 8253 2922 8253 2922 8239 2907 8223
      2896 8227 2896 8231
TIME...MOT...LOC 1909Z 212DEG 16KT 2902 8247

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

BOOTHE

Special Weather Statement
National Weather Service Jacksonville FL
314 PM EDT Tue Aug 24 2021

FLZ132-232-242000-
Eastern Clay FL-Western Clay FL-
314 PM EDT Tue Aug 24 2021

...Strong thunderstorms will impact portions of western Clay County
through 400 PM EDT...

At 314 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from Bellair-Meadowbrook Terrace to near Keystone
Heights. These storms were nearly stationary.

HAZARD...Winds in excess of 40 mph and minor flooding due to heavy
         rainfall.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor flooding due to heavy rainfall is
         possible.

Locations impacted include...
Keystone Heights, Middleburg, Doctors Inlet, Lakeside, Kingsley, Camp
Blanding, Penney Farms and Asbury Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

&&

LAT...LON 2982 8192 2983 8205 2992 8205 3019 8181
      3019 8179 3012 8171
TIME...MOT...LOC 1914Z 195DEG 2KT 3017 8176 2986 8197

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

BOOTHE

Special Weather Statement
National Weather Service Jacksonville FL
325 PM EDT Tue Aug 24 2021

FLZ232-242000-
Western Clay FL-
325 PM EDT Tue Aug 24 2021

...A strong thunderstorm will impact portions of northwestern Clay
County through 400 PM EDT...

At 324 PM EDT, Doppler radar was tracking a strong thunderstorm near
Middleburg, moving north at 5 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

This storm will remain over mainly rural areas of northwestern Clay
County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

&&

LAT...LON 2992 8205 3012 8205 3012 8187
TIME...MOT...LOC 1924Z 190DEG 10KT 3009 8194

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

BOOTHE

Special Weather Statement
National Weather Service Jacksonville FL
336 PM EDT Tue Aug 24 2021

FLZ125-225-425-242000-
Western Duval FL-Trout River FL-Coastal Duval FL-
336 PM EDT Tue Aug 24 2021

...Strong thunderstorms will impact portions of central Duval County
through 400 PM EDT...

At 336 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Cisco Gardens to Craig Field. Movement was
northeast at 10 mph.

HAZARD...Winds up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Jacksonville, Jacksonville International Arpt, Arlington, Oceanway,
Craig Field, Fort Caroline and Tallyrand.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

&&

LAT...LON 3051 8172 3039 8142 3030 8152 3040 8185
TIME...MOT...LOC 1936Z 229DEG 8KT 3043 8179 3034 8152

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

BOOTHE

Special Weather Statement
National Weather Service Jacksonville FL
343 PM EDT Tue Aug 24 2021

FLZ232-237-242030-
Western Clay FL-Western Putnam FL-
343 PM EDT Tue Aug 24 2021

...Strong thunderstorms will impact portions of northwestern Putnam
and south central Clay Counties through 430 PM EDT...

At 343 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 10 miles southwest of Green Cove Springs to
near George's Lake to near Interlachen. These storms were nearly
stationary.

HAZARD...Winds in excess of 40 mph and minor flooding due to heavy
         rainfall.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor flooding due to heavy rainfall is
         possible.

Locations impacted include...
Interlachen, Melrose Landing, George's Lake, Bardin, Hollister,
Florahome, Johnson, Putnam Hall, Carraway and Mannville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 2960 8206 2994 8181 2991 8170 2973 8170
      2950 8182 2949 8184 2952 8185 2951 8189
      2951 8190 2950 8191 2951 8194 2950 8197
      2950 8202 2947 8205
TIME...MOT...LOC 1943Z 191DEG 2KT 2987 8180 2977 8181 2961 8194

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

BOOTHE

Special Weather Statement
National Weather Service Jacksonville FL
349 PM EDT Tue Aug 24 2021

FLZ122-222-242030-
Southern Columbia FL-Northern Columbia FL-
349 PM EDT Tue Aug 24 2021

...A strong thunderstorm will impact portions of central Columbia
County through 430 PM EDT...

At 349 PM EDT, Doppler radar was tracking a strong thunderstorm over
Watertown, or near Lake City, moving north at 10 mph.

HAZARD...Winds in excess of 40 mph and minor flooding due to heavy
         rainfall.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor flooding due to heavy rainfall is
         possible.

Locations impacted include...
Lake City, Five Points, Watertown and Lulu.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

&&

LAT...LON 3033 8268 3030 8246 3019 8246 3010 8249
      3008 8269
TIME...MOT...LOC 1949Z 194DEG 9KT 3020 8258

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

BOOTHE