653
FXUS62 KJAX 200207
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1007 PM EDT Tue Aug 19 2025

...POWERFUL SWELLS FROM HURRICANE ERIN WILL IMPACT OUR LOCAL
WATERS THROUGH FRIDAY, CREATING DANGEROUS SURF CONDITIONS...
...MINOR COASTAL FLOODING AND MODERATE BEACH EROSION POSSIBLE ON
WEDNESDAY...
...SHOWERS AND THUNDERSTORMS BECOME WIDESPREAD FROM FRIDAY THROUGH
THE WEEKEND...

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

.UPDATE...
Issued at 1007 PM EDT Tue Aug 19 2025

Late evening surface analysis depicts the obscured eye of Category
2 Hurricane Erin positioned about 550 miles to the southeast of
Jacksonville. Erin was in the process of turning northward and is
beginning to gradually accelerate as well. Meanwhile, high
pressure (1025 millibars) was positioned over New England and was
wedging southwestward down the spine of the Appalachians.
Aloft..."Heat Wave" ridging has retrograded westward to the Four
Corners region of the Desert Southwest, with troughing gradually
digging southeastward from the Great Lakes region towards the Ohio
Valley. Latest GOES-East derived Total Precipitable Water imagery
indicates that a drier air mass was advecting southwestward from
southeast GA to the Interstate 10 corridor, where values were
mostly in the 1.6 - 1.7 inch range. Deeper moisture, featuring
PWATs of 1.8 - 2 inches, was located over north central FL.
Breezy, convergent onshore flow was advecting widely scattered
showers onshore along coastal St. Johns and Flagler Counties, with
an earlier briefly heavier thunderstorm that moved onshore just
north of St. Augustine weakening as it crossed the St. Johns
River. Breezy onshore winds prevail at coastal locations, keeping
temperatures at 02Z in the lower 80s, while decoupling winds at
inland locations were allowing temperatures to fall to the upper
70s to around 80 at most inland locations. Dewpoints remain in the
70s, although locations near the Altamaha River have fallen to
around 70 late this evening.

Occasional coastal showers will remain possible overnight, mainly
for locations south of St. Augustine, where deeper moisture will
exist. Winds will shift to north-notheasterly after midnight and
then northerly towards sunrise, with a gradually tightening local
pressure gradient expected at coastal locations towards sunrise.
Lows tonight will range from the lower 70s inland to around 80 at
coastal locations.

&&

.SHORT TERM...(Wednesday through Thursday night)

Wednesday, Hurricane Erin will move northward east of our region,
crossing our parallel, by afternoon while surface high pressure
ridge axis begins to weaken from the New England coast to the
Carolina Piedmont. Winds will turn more northerly by afternoon
with breezier conditions at the NE FL coast 15-20 mph with gusts
to 30 mph and down the St Johns river while 10-15 mph inland.
Otherwise convergent showers will mainly remain over the coastal
waters with only occasional scattered showers and isolated T`storms
moving onshore, but staying east of highway 301. Highs will be
in the low/mid 90s inland and upper 80s to near 90 at the coast
with max heat indices 100-106.

Showers and a few T`storms will end by around sunset with winds
overnight diminishing and backing to the west as the circulation
of Erin moves away to the north northeast. Lows will be in the
low/mid 70s inland, and upper 70s along the coast.

Thursday, Dry air (below normal PWAT levels 1.5-1.8 inches) will
initially be in place, but gradually increase towards around 2.0
inches as flow aloft becomes westerly ahead of a sinking frontal
boundary moving towards the Gulf coast and northern FL. Surface
winds from the west northwest winds will drive the Gulf seabreeze
inland towards I-95 before encountering the Atlantic seabreeze
pinned near the coast where scattered to numerous showers and
T`storms will develop in the afternoon. Isolated stronger T`storms
may pulse along the NE FL coast where better convergence will
set up between the overall west northwest flow and southeasterly
Atlantic seabreeze winds. Slightly slower T`storm motion from
the northwest and increasing layer moisture will support a
localized flood risk as heavy rainfall rates of 2-3 inches per
hour may produce locally heavy rainfall totals. Gusty winds
from wet downburst 40-55 mph will also be possible. The drier
airmass and westerly winds will allow highs to rise to the
mid/upper 90s inland and low 90s along the coast with max heat
index values rising to near Heat advisory thresholds 104-108.

&&

.LONG TERM...(Friday through next Tuesday)

A frontal boundary will drift south into the area Friday and
remain through the weekend with higher layer moisture levels
(PWATS 2.00 -2 2.25 inches) pool along the front. Shortwave
energy aloft, lift along the front at the surface and along
converging seabreezes will increase coverage of showers and
T`storms from numerous to widespread. WPC has a Marginal risk
of excessive rainfall Friday into Saturday for locally heavy
rainfall potential. Skies will remain mostly cloudy with
west to southwest winds turning southeasterly from I-95 to
the coast behind the Atlantic seabreeze.

Next Monday and Tuesday, another cold front will arrive as a
stronger mid/upper level trough pushes southeast from the upper
Midwest southeastward into the central/southern Appalachian
and Mid Atlantic. High pressure at the surface will build in
from the northwest late Monday into Tuesday with decreasing
chances for showers and T`storms as much drier air filters
back into the area (PWATS under 1.5 inches).

High temperatures will begin near normal Friday into Saturday
and then trend above normal into early next week. Lows will
be near to slightly above normal with below normal highs by
the end of the period over inland SE GA.

&&

.AVIATION...
(00Z TAFS)
Issued at 808 PM EDT Tue Aug 19 2025

Showers and possibly a brief thunderstorm will occasionally impact
SGJ through around 04Z. A TEMPO group was used for MVFR conditions
during heavier downpours. VFR conditions should then prevail at
SGJ by 06Z. Showers will otherwise remain south of the Duval
County terminals through at least 05Z tonight, with VFR conditions
prevailing elsewhere through at least 08Z. Marine stratocumulus
and coastal showers may move onshore during the predawn and early
morning hours at the SSI and SGJ coastal terminals, and PROB30
groups for MVFR conditions during heavier downpours were placed in
these TAFs from 11Z/12Z through 14Z/15Z. A few light showers could
approach CRG/JAX towards sunrise, with activity potentially
impacting these terminals after 13Z. We also used PROB30 groups
during the mid to late morning hours for MVFR conditions during
heavier downpours at JAX and CRG. Confidence was too low to
indicate anything other than vicinity shower activity at VQQ and
GNV during the late morning and afternoon hours. Breezy
northeasterly surface winds that will be sustained at 10-15 knots
outside of heavier shower activity will prevail through around
04Z, while northeasterly surface winds elsewhere subside to around
5 knots. Northerly surface winds will then develop at the regional
terminals after 06Z, with speeds increasing to around 10 knots at
the coastal terminals towards 10Z and then around 15 knots and
gusty after 15Z. Northerly surface winds will increase to 5-10
knots shortly after sunrise at the inland terminals and then 10-15
knots by 15Z Wednesday.

&&

.MARINE...
Issued at 1007 PM EDT Tue Aug 19 2025

High pressure positioned over coastal New England will continue to
wedge into the southeastern states as Hurricane Erin turns
northward tonight, remaining well east of the Gulf Stream waters
adjacent to our area. Breezy northeasterly winds, sustained at
Caution levels of 15-20 knots, will shift to northerly by sunrise
on Wednesday as powerful ocean swells increase in frequency
across our local waters. Seas will build to 6-9 feet near shore
after midnight and will then peak in the 7-10 foot range on
Wednesday and Wednesday night. Meanwhile, seas will build to 8-11
feet offshore overnight, peaking in the 9-13 foot range on
Wednesday and Wednesday night. An extended period of Small Craft
conditions will continue through Thursday night near shore and
through Saturday offshore due to these lingering swells. Erin will
turn northeastward by late Thursday, allowing a frontal boundary
to push into the southeastern states and for prevailing offshore
winds to develop across our local waters. This front will stall
across the region Friday through the weekend, bringing rounds of
showers and thunderstorms to our area.

Rip Currents / Beach Erosion: Breaker heights will continue to
build overnight through Wednesday, peaking in the 8-10 foot range
at the northeast FL beaches and 6-8 feet at the southeast GA
beaches. These breakers will likely produce moderate beach erosion
at area beaches through Thursday, particularly around times of
high tide. A high risk of deadly rip currents will continue
through at least Friday, with this high risk potentially lingering
into the weekend at the northeast FL beaches, with a higher end
moderate risk at the southeast GA beaches.

&&

.FIRE WEATHER...
Issued at 1007 PM EDT Tue Aug 19 2025

Surface and transport winds will shift to northerly on
Wednesday, with breezy conditions creating good daytime dispersion
values at coastal locations and marginally high values inland.
Surface and transport winds will shift to northwesterly by early
Thursday and then westerly during the afternoon hours. These winds
will combine with elevated mixing heights to create good daytime
dispersion values across southeast GA and coastal northeast FL,
with high values possible across inland portions of northeast and
north central FL. Surface and transport winds will then shift to
southwesterly on Friday, with elevated mixing heights creating
fair to good daytime dispersion values before showers and
thunderstorms increase in coverage during the mid to late
afternoon hours.

&&

.COASTAL FLOODING...
Issued at 1007 PM EDT Tue Aug 19 2025

Increasing astronomical tides during the upcoming new moon are
expected on Wednesday, with swells from distant Hurricane Erin
likely bringing water levels to near minor flood along our local
Atlantic coast. Latest guidance indicates that minor tidal
flooding of 1.5 - 2 feet above the Mean Higher High Water (MHHW)
datum will be possible during the early evening high tide on
Wednesday, and a Coastal Flood Advisory may be required for our
Atlantic coastal counties, with elevated tidal levels likely
extending to the Intracoastal Waterway (ICCW). Strengthening
northerly winds will likely also raise water levels within the St.
Johns River basin by late Wednesday and especially Thursday,
where a few gauges south of downtown Jacksonville potentially
climbing to 1 - 1.5 feet above MHHW, which is mostly below minor
flood levels.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  72  93  73  95 /  10  20   0  20
SSI  77  92  77  94 /  20  20   0  20
JAX  75  94  75  97 /  20  40   0  40
SGJ  77  91  76  94 /  40  50  10  40
GNV  74  94  75  95 /  10  30  10  50
OCF  74  93  75  92 /  10  40  10  70

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through late Thursday night for FLZ124-125-
     138-233-333.

     High Surf Advisory until 2 AM EDT Friday for FLZ124-125-138-233-
     333.

GA...High Rip Current Risk through late Thursday night for GAZ154-166.

     High Surf Advisory until 2 AM EDT Friday for GAZ154-166.

AM...Small Craft Advisory until 4 AM EDT Friday for AMZ450-452-454.

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

&&

$$