136
FXUS62 KJAX 170753
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
353 AM EDT Sat May 17 2025

...NEAR RECORD HEAT CONTINUES THROUGH THE MIDDLE OF NEXT WEEK...
...STRONG STORMS POSSIBLE LATE SUN AFTERNOON IN SOUTHEAST GA...
...COLD FRONTAL PASSAGE SLATED FOR WED NIGHT AND EARLY THURS...

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

.SYNOPSIS...
Issued at 354 AM EDT Sat May 17 2025

Overnight surface analysis depicts Atlantic high pressure
extending its axis westward across the FL peninsula and the
southeastern Gulf. Meanwhile, pair of cold fronts extend
southwestward from strong low pressure (990 millibars) that was
migrating across the Great Lakes region, with these boundaries
pushing across the Upper Midwest and approaching the Ohio,
Tennessee, and lower Mississippi Valleys. Aloft...deep-layered
ridging that extends across the Gulf and the FL peninsula was
flattening as deep troughing migrates across the Great Lakes
states, with a 120 knot jet streak positioned around 250
millibars (around 35,000 feet) migrating across the Ozarks and
the Tennessee Valley in between these features that was fueling a
severe weather outbreak across the lower Mississippi and Tennessee
Valleys. Latest derived Total Precipitable Water imagery indicates
that a dry and subsident air mass prevails locally, with PWATs of
only around 1 inch at most locations. Brisk northwesterly flow
above 500 millibars (around 25,000 feet) located on the periphery
of the ridge over the Gulf was advecting thin cirrus into our
region, with thicker cirrostratus located upstream across the Deep
South. A west-southwesterly breeze was keeping temperatures in the
upper 60s and lower 70s at most locations as of 07Z, with
dewpoints mostly in the low and middle 60s.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 354 AM EDT Sat May 17 2025

Cirrus cloud cover will overspread our region briefly this
morning, with some thicker cirrostratus at times for locations
along and north of Interstate 10. Thinner cirrus south of I-10
may allow for some low stratus ceilings and possibly some patchy
fog to develop during the predawn and early morning hours today
for inland portions of north central FL. Otherwise, ridging aloft
will continue to flatten across the Gulf and FL peninsula as deep
troughing migrates slowly eastward across the eastern Great Lakes
through tonight. This will allow a frontal boundary to push
through the Tennessee Valley and the Carolinas by late tonight. A
ribbon of deeper moisture will pool downstream of this frontal
boundary across central AL and GA this afternoon, with a jet
streak migrating eastward across the Tennessee Valley and the
Carolinas helping to develop a squall line of strong to severe
thunderstorms that will approach the Altamaha and Ocmulgee Rivers
by late afternoon. However, the best forcing and dynamics
associated with this jet streak will remain situated just north of
our area, likely resulting in the squall line breaking up while
weakening towards sunset. Widely scattered showers and possibly
and few thunderstorms will migrate across the Ocmulgee and
Altamaha Rivers towards sunset, with activity then dissipating
before reaching Waycross and points eastward to coastal southeast
GA.

Our local pressure gradient will remain rather tight across our
area today as the storm system passes well to the north of our
region. High altitude cloudiness should thin out this afternoon. A
hot, dry, and subsident air mass will persist for locations south
of Waycross, and the Atlantic sea breeze may remain just east of
area beaches until late afternoon, which will allow for another
day of record breaking heat to again extend all the way to
coastal locations. Increasing afternoon cloudiness will keep highs
in the low to mid 90s for locations north of Waycross, while mid
to upper 90s continue elsewhere. Dewpoints falling through the
low and mid 60s this afternoon will keep maximum heat index values
around 100.

Any leftover, low-topped convection over inland southeast GA
should dissipate during the early to mid-evening hours. Debris
clouds from this activity will thin out after midnight, setting
the stage for fog and low stratus ceilings to advect eastward off
Apalachee Bay and across the Suwannee Valley overnight. This bank
of low stratus and fog should continue advecting eastward along
the I-10 corridor during the predawn hours, possibly approaching
the I-95 corridor towards sunrise. Lows tonight will again only
fall to the upper 60s and lower 70s.

&&

.SHORT TERM...
(Sunday through Monday night)
Issued at 354 AM EDT Sat May 17 2025

A broad high pressure ridge will extend across south FL this
period. A front will be stalled across central GA on Sunday, then
lift back to the north on Monday.

The flow aloft on Sunday will allow weak waves to move east across
SE GA. These waves, coupled with convergence associated with frontal
boundary, and diurnal heating will lead to potential for a few
showers and storms over SE GA Sunday afternoon. Low level moisture
will result in patchy fog potential across area Sunday night.

Dry weather is expected for Monday.

With the west southwest flow, the east coast sea breeze will
struggle to move inland Sunday, likely not making it past I95. Highs
inland in the middle 90s will be common. With the sea breeze having
a harder time pushing inland, highs at the coast should still reach
the lower 90s before the sea breeze moves inland. Temperatures will
remain above average Sunday night. The sea breeze will once again
struggle to push inland against the prevailing flow from the west
southwest Monday. So, again the heat will get all the way to
the coast before the sea breeze pushes in. Highs Monday will range
from the middle 90s inland, to the lower to mid 90s coast. The above
average temperatures will continue Monday night.

Inland fog potential Monday night due to flow off the Gulf.

&&

.LONG TERM...
(Tuesday through Friday)
Issued at 354 AM EDT Sat May 17 2025

The high will push further away to the south southeast Tuesday, as a
frontal system approaches from the northwest. Tuesday will be a
dry day, with temperatures above seasonal averages. After a dry
night Tuesday night, the front will move into the southeast
Wednesday. The front will then move through the area through
Thursday morning. A round of showers and thunderstorms will
accompany the front Wednesday through early Thursday. A
significant change in temperatures is expected with the front,
hinting at the potential for strong to possibly severe storms with
the passage.

Temperatures will continue above seasonal averages through
Wednesday, then near to below Thursday into Friday.

&&

.AVIATION...
(06Z TAFS)
Issued at 144 AM EDT Sat May 17 2025

VFR conditions will prevail at the regional terminals. Low stratus
ceilings and fog are expected to develop over the Suwannee Valley
and portions of inland southeast GA during the predawn and early
morning hours on Saturday, but these lower clouds and visibility
restrictions should remain west of the regional terminals before
dissipating during the mid-morning hours. Southwesterly surface
winds sustained around 5 knots overnight will shift to west-
southwesterly, with speeds increasing to 10-15 knots by 15Z. The
Atlantic sea breeze boundary will struggle to move onshore on
Saturday afternoon, with winds at the SSI and SGJ coastal
terminals possibly shifting to south-southwesterly as this
boundary approaches both terminals after 20Z. Southwesterly
surface winds will then diminish to 5-10 knots at the regional
terminals towards 01Z Sunday.

&&

.MARINE...
Issued at 354 AM EDT Sat May 17 2025

Atlantic high pressure will continue to extend its axis westward
across the Florida peninsula and into the eastern Gulf through
early next week, creating a prevailing west southwesterly wind
flow across our local waters. Seas of 2 to 3 feet will prevail
both near shore and offshore through Tuesday night. Meanwhile, a
frontal boundary currently pushing across the Ohio and Tennessee
Valleys will stall to the north of our area on Sunday, with
showers and possibly a few strong thunderstorms possibly impacting
the Georgia waters during the late afternoon and evening hours.
This front will lift northward early next week in advance of a
cold front that will move across our local waters on Wednesday
night and early Thursday. Scattered showers and thunderstorms may
accompany this frontal passage on Wednesday afternoon and night.
Strengthening southwesterly winds will result in seas building
slightly to 3-4 feet offshore by midweek. High pressure will then
build into the southeastern states late this week and during the
beginning of Memorial Day weekend in the wake of this frontal
passage.

Rip Currents: Prevailing offshore winds and low surf heights will
keep a low risk in place at all area beaches today. Afternoon sea
breezes may combine with a lingering easterly ocean swell to
create a moderate risk at the northeast FL beaches on Sunday and
Monday, but we opted to keep the risk low at this time due to
expected low surf heights that will persist through at least
midweek.

&&

.FIRE WEATHER...
Issued at 354 AM EDT Sat May 17 2025

A dry and very hot air mass will continue across our region today,
with only isolated late afternoon and evening thunderstorms
possible for locations north of Waycross. Minimum humidity values
will fall to around 30 percent this afternoon for locations south
of Waycross, extending all the way to coastal locations, as the
Atlantic sea breeze remains pinned along area beaches. Otherwise,
breezy transport winds will combine with elevated mixing heights
to create pockets of high daytime dispersion values at inland
locations, while good values otherwise prevail. Widely scattered
strong to isolated severe thunderstorms will be possible across
southeast GA late on Sunday afternoon and evening. Minimum
humidity values will fall to the 30-35 percent range for inland
locations to the south of Waycross. Breezy westerly transport
winds and elevated mixing heights will again create pockets of
high daytime dispersion values at inland locations, with good
values expected elsewhere. Surface and transport winds will shift
to southwesterly on Monday, with elevated mixing heights again
resulting in high daytime dispersion values at some inland
locations, while good values otherwise prevail across our area.

&&

.CLIMATE...
Issued at 354 AM EDT Sat May 17 2025

Daily Record High Temperatures through Wednesday at our designated
climate sites:

               Sat 5/17  Sun 5/18  Mon 5/19 Tues 5/20  Wed 5/21
               --------------------------------------------------
Jacksonville   96/1995   96/1899   97/1960   99/1962   99/1938
Gainesville    96/1915   97/1930   99/1899   97/1938   100/1938
Alma, GA       94/2001   95/2001   97/1960   99/1962   97/1962
Craig Airport  93/2001   93/2001   92/2006   97/2006   98/2006

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  93  71  92  68 /  10  10  50   0
SSI  94  73  90  72 /   0   0  30  20
JAX  97  69  97  68 /   0   0   0   0
SGJ  96  70  94  69 /   0   0   0   0
GNV  96  67  95  65 /   0   0   0   0
OCF  94  67  93  67 /   0   0   0   0

&&

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

$$