Special Weather Statement, NWS Jacksonville, FL

Area Forecast Discussion
National Weather Service Jacksonville FL
755 AM EDT Thu Aug 5 2021

.AVIATION...
[Through 12Z Friday]

Stalled boundary is along a zone from coastal GA, then southwest
to the near Lake City/Live Oak and into the Gulf of Mexico, which
will continue to produce numerous to widespread showers and a few
thunderstorms along this line. As a result, t-storms will be
around KSSI over the next couple of hours at times with IFR vsby
expected. Otherwise, some scattered light rain and low stratus for
the rest of the TAFs with occasional MVFR/IFR, and brief LIFR at
KVQQ this morning. Rounds of showers and some t-storms expected by
later this morning and especially into the mid to late afternoon
hours, with TEMPO IFR conditions with heavy rainfall/low vsby.
There may be some improving conditions after 00Z as some of the
heavier rainfall begins to ease, but MVFR ceilings possible, with
lower ceilings also possible around KSSI toward sunrise Friday.

&&

.PREV DISCUSSION [314 AM EDT]...

.NEAR TERM [Through Tonight]...

Frontal boundary has sagged southward all the way into NE FL and
is currently stalled near the I-10 corridor, while a weak low
pressure center has developed on the boundary in the NE Gulf of
Mexico. Small waves of energy will rotate around the east side of
this low and push northward through NE FL/SE GA today and tonight
with models trying to slowly lift the low northward late tonight
along with the boundary trying to pull northward into SE GA by
early Friday morning. Precipitable Water Amounts of well over 2
inches cover all of NE FL/SE GA along this boundary and will
continue the threat of locally heavy rainfall at any time a weak
wave of energy rotates through, but will be enhanced slightly
during peak heating this afternoon across the area, although with
the widespread cloudiness there will not be much heating with peak
Max temps only in the lower to middle 80s across the area, so
locally heavy rainfall will likely remain confined to activity
along the frontal boundary as it drifts slowly northward through
the next 24 hours and along any convection as it moves off the NE
Gulf of Mexico and into the I-75 corridor of inland NE FL, due to
this random nature of this locally heavy rainfall, very tough to
nail down any exact "Flood Watch" area, so will not issue any
widespread watch at this time, but as discussed in the "Hydrology"
section below, any isolated 3 to 5 inch storm totals will likely
lead to the issuance of Flood Warnings and continuation of river
flooding along the St. Mary's and Santa Fe Basins. The heavy
convection early this evening should fade once again after sunset
and shift northward into SE GA with the frontal boundary and along
the I-75 corridor of inland NE FL, leaving most of the I-95
corridor from JAX southward mainly dry during the overnight hours.
Near normal climo lows in the 70s expected tonight.

.SHORT TERM [Friday Through Saturday Night]...

Frontal boundary will weaken and shift north across south Georgia
on Friday as an upper trough moves from the Mississippi River
Valley into the southeast. This trough will enhance convection on
Friday especially over se Georgia and the Suwannee Valley where
the highest rain chances will exist. The threat of heavy rainfall
will persist as deep moisture remains across the area. The upper
trough axis will move across on Saturday continuing the numerous
shower and thunderstorm activity.

.LONG TERM [Sunday Through Wednesday]...

Deep layer ridge to the south will build north across the area
early next week. This will bring a more typical summer-like
pattern with increased temperatures. With light winds, the
seabreezes will move inland and merge over the interior each
afternoon/evening. Scattered to numerous late day storms will
occur inland with daytime temperatures reaching the lower 90s.

.MARINE...

Southwest winds continue across the NE FL waters south of the
frontal boundary at close to 15 knots, with variable winds across
the SE GA waters near the frontal boundary today. All waters
shift back to the south in the 10-15 knot range on Friday as
front lifts back north of the region and High Pressure ridge
builds east of the waters which continue through the weekend.
Local sea breezes from the Southeast will develop along the Atlc
Coast through the weekend.

Rip Currents: Low Risk will continue in the offshore flow today
will with South flow and Southeast sea breezes possible for Friday
into the Weekend, a lower end Moderate risk will be possible.

.HYDROLOGY...

Another round of heavy rainfall with convection today with general
1 to 2 inch amounts expected with the isolated 3 to 5 inch totals
where storms get stalled along the old frontal boundary this
afternoon. Flooding will continue to expand along the Santa Fe and
St. Mary's River Basins, and the North Fork of Black Creek already
into Action stage and may reach Minor Flood with another round of
rainfall today.

&&

.PRELIMINARY POINT TEMPS/POPS...

AMG  85  71  85  70  88 /  30  30  80  20  60
SSI  84  75  88  76  89 / 100  60  70  30  50
JAX  84  73  90  74  90 / 100  50  70  30  60
SGJ  86  74  90  74  90 /  90  40  60  20  60
GNV  83  72  88  72  89 / 100  50  70  10  60
OCF  84  73  90  73  91 / 100  50  60  10  60

&&

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

Special Weather Statement
National Weather Service Jacksonville FL
815 AM EDT Thu Aug 5 2021

FLZ021-023-030-035-222-051345-
Southern Columbia FL-Baker FL-Union FL-Suwannee FL-Gilchrist FL-
815 AM EDT Thu Aug 5 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN GILCHRIST...SOUTHWESTERN
BAKER...WESTERN UNION...SOUTHERN COLUMBIA AND SOUTHEASTERN SUWANNEE
COUNTIES UNTIL 945 AM EDT...

* At 812 AM EDT, National Weather Service meteorologists were
  tracking showers and thunderstorms near Fort White, or near
  Ichetucknee Spring, moving northeast at 15 mph.

* Minor flooding due to heavy rainfall is possible with these
  showers and storms.

* Locations impacted include...
  Bell, Ichetucknee Spring, Columbia, Fort White, Palestine
  Community, Upland Pines, Groves, Providence, Lulu and Olustee.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3026 8237 3007 8227 2994 8250 2994 8252
      2992 8258 2990 8258 2969 8296 2971 8294
      2972 8296 2972 8294 2977 8295 2980 8292
      2981 8293 2983 8289 2988 8287 2990 8290
      2989 8292 2995 8292 2996 8295 3000 8297
TIME...MOT...LOC 1212Z 239DEG 12KT 2996 8268

SHASHY