310
FXUS62 KJAX 212330
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
730 PM EDT Thu Aug 21 2025

...New UPDATE, AVIATION...

.UPDATE...
Issued at 718 PM EDT Thu Aug 21 2025

For the latest NE FL and SE GA Daily Key Messages please visit:
https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf

Thunderstorm outflow mergers still taking place along the Altamaha
River Basin across inland SE GA and along the I-75 corridor of
inland NE FL, with heavy rainfall and gusty winds to 40 mph that
will linger until 9-10pm before weakening. Fair skies and mild
temps overnight with lows in the lower to middle 70s and some
patchy fog over inland areas and upper 70s along the Atlantic
Coastal areas. Expect some diurnal heating ahead of approaching
frontal boundary from the NW on Friday and a combination of
plentiful moisture aloft with PWATs over 2 inches and sea breeze
fronts pushing inland and merging with convective outflow
boundaries will create numerous to widespread thunderstorm
activity by the afternoon hours area-wide, with the highest
chances across all of SE GA and the I-95/US-301 corridors of NE
FL. Max temps will top out around 90F prior to the onset of
afternoon convection. Slow storm motion will lead to heavy
rainfall and localized flooding as the main threats, but expect a
few strong to isolated severe storms with gusty downburst winds to
40-60 mph as well.

&&

.NEAR TERM...through Tonight...

Convection is ongoing and expected to be much more present today
as compared to Wednesday thanks to a lingering trough/boundary in
the wake of departing Hurricane Erin, in addition to a more west
to southwest steering flow advecting higher layer moisture back
into the area. Convection this afternoon has mostly fired over far
southern areas as well as near a differential moisture boundary
from about Coffee County GA southeastward towards Jax Beach,
though the east coast sea breeze very slowly pushing inward
through this evening will help to enhance shower and t`storm
coverage accordingly. Main "corridor" expected to be mainly
between about HWY 301 and I-95, with the highest coverage
generally over northeast FL where the highest mean layer
moisture/PWATs are. Temps are still fairly warm aloft, but some
localized dry air entrainment aloft could result in some gusts in
the 40-50mph range, especially where boundary collisions occur.
Heavy rainfall/minor flooding risk looks to lower today with PWATs
still slightly below normal and storm motion around 10-15mph, so
it will take modest to significant training of storms for flooding
concerns today. Highs in the mid 90s will be common this afternoon
and evening, with some areas already hitting these numbers before
the onset of convection.

With the boundary lingering overnight, hi-res guidance has been
suggesting a slower burn with respect to convection ending after
sunset, especially over parts of southeast GA closer to the
boundary and also where the deeper moisture will take longer to
advect in this evening. Low temperatures could therefore vary a
decent amount in addition to cloud cover/rain chances, though
expecting shower and storms to generally taper earlier over
northeast FL with lows mainly low to mid 70s.

For the latest NE FL and SE GA Daily Key Messages please visit:
https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf

&&

.SHORT TERM...Friday through Saturday night...

Increasing thunderstorm coverage and potential for more intense
thunderstorms is expected Friday into Saturday as a trailing
trough behind Hurricane Erin lays across southeastern GA.

That feature will gradually settle farther south into southeast
GA and hinge off the coast as a dampening mid level wave
approaches it. Given the abundant deep moisture, sea breeze
interaction, and ribbons of vorticity tracking the surface trough,
it`s likely to see numerous thunderstorms developing Friday
afternoon and potential continue until midnight in the vicinity of
the trough.

As the weekend begins a parade of shortwave energy riding along
the boundary is progged to stir up a weak surface circulation
somewhere along the GA/SC coast. The northerly flow on western
side of the circulation may push the boundary farther south toward
the FL/GA state line, focusing the highest coverage of storms
along it. Given the steering flow becoming boundary-parallel,
there may be instances of training convection, particularly
Saturday afternoon and increase the risk of flooding.

For both days the primary concern will be heavy downpours which
may lead to pockets of flooding where downpours persist or train
across. Higher-end precipitation amounts, per HiRes guidance,
could reach up to 4" in localized locations. However, with dry
antecedent conditions (low soil moistures), uncertainty in the
position and strengthen of the surface low circulation, and
localized nature of heavy downpours, decided to hold off a Flood
Watch for portions of SE GA north of US-82.

Highs are expected to reach the lower 90s Friday before
convection initiates while a mostly cloudy morning Saturday will
inhibit insolation, keeping highs in the upper 80s for most
areas.

&&

.LONG TERM...Sunday through Wednesday...

Broader cyclonic flow will begin to carve out across the eastern
US late this weekend and into next week. The digging upper trough
will push a cool front into the southeastern states sometime
Tuesday. Dry air behind the feature will dry out conditions across
SE GA as PWATs drop below 1.5" and potentially near 1" (very low
this time of year). However, there is significant uncertainty
regarding where the front will ultimately stall. That said, PoPs
favor a 30-50% chance of rain Tuesday through Wednesday across NE
FL. Temperatures will hover in the average range for late August
despite the incoming front next week.

&&

.AVIATION...
(00Z TAFS)
Issued at 718 PM EDT Thu Aug 21 2025

IFR conds in TSRA activity ongoing at GNV through 00-01Z time
frame otherwise rainfall and lingering VCTS will slowly fade at
the other TAF sites through the 01-02Z time frame with mostly VFR
conds overnight and convective debris high clouds and light winds.
Patchy MVFR fog expected at the inland TAF sites of GNV/VQQ/JAX
from the 08-12Z time frame. High rainfall chances through the
afternoon hours and have placed -SHRA VCTS for all sites from
16-17Z onward and have added PROB30 groups for MVFR TSRA activity
at all TAF sites from 17-23Z for GNV and 18-24Z for all the other
TAF sites across NE FL and SE GA.

&&

.MARINE...
Issued at 1240 PM EDT Thu Aug 21 2025

Lingering swells from Hurricane Erin will continue to subside
across area waters through tonight. A surface trough will shift
southward toward the local waters late tonight and then linger
across the local waters through the weekend, brining an increase
in shower and thunderstorm activity. A daily sea breeze through
the weekend will result in a shift in the flow each afternoon
through Friday, though southwesterly offshore flow will be more
dominant this weekend.

Rip Currents: High risk for rip currents continues through Friday
as Erin pulls away, though breakers have dropped below high surf
advisory in the surf zone.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  72  90  72  86 /  40  90  70  90
SSI  76  87  76  87 /  40  80  80  90
JAX  74  91  74  90 /  30  80  70  90
SGJ  75  90  75  90 /  40  90  60  90
GNV  73  90  74  90 /  20  80  50  90
OCF  74  89  74  89 /  30  90  50  90

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Friday evening for FLZ124-125-138-
     233-333.

GA...High Rip Current Risk through Friday evening for GAZ154-166.

AM...Small Craft Advisory until 8 AM EDT Friday for AMZ470-472-474.

&&

$$