736
FXUS62 KJAX 171847
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
247 PM EDT Thu Jul 17 2025

...STRONG STORMS POSSIBLE INLAND LATE THIS AFTERNOON & EVENING...
...HEAT AND HUMIDITY BUILD ON FRIDAY...
...HEAT ADVISORY CONDITIONS THIS WEEKEND AND EARLY NEXT WEEK...

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 248 PM EDT Thu Jul 17 2025

Afternoon surface analysis depicts Atlantic high pressure (1025
millibars) centered near Bermuda, with this feature extending its
axis west-southwestward across the FL peninsula. Meanwhile, the
broad center of Invest 93L (1013 millibars) was moving inland over
coastal Mississippi and Louisiana. Aloft...ridges were located
along the southeastern seaboard and also to the east of the
Bahamas, with weak troughing situated between these features that
extends from the FL Keys northeastward across the northwestern
Bahamas. Latest GOES-East derived Total Precipitable Water imagery
indicates that PWATs were mostly in the 1.75 - 2.0 inch range
across our area, with deeper moisture values located to the west
of the Suwannee River and along the Interstate 4 corridor. Only
isolated convection has been developing along mesoscale
boundaries such as the Atlantic and Gulf Coast sea breezes and the
St. Johns River breeze thus far this afternoon, with brisk low
level south-southeasterly flow pushing this activity north-
northwestward around 15-20 mph. Inland temperatures have soared to
the 90-95 degree range, with dewpoints in the 70s resulting in
heat index values of 100-105 degrees at most locations. Coastal
temperatures have cooled to the mid to upper 80s behind the inland
moving Atlantic sea breeze.

&&

.NEAR TERM...
(through Tonight)
Issued at 248 PM EDT Thu Jul 17 2025

Seasonable moisture values should fuel an increasing coverage of
showers and thunderstorms that will continue to develop along
mesoscale boundaries late this afternoon, with numerous
thunderstorms expected for locations west of I-95 and south of
I-10 in northeast and north central FL late this afternoon through
the early to mid evening. This activity will be steered quickly
north-northwestward this afternoon, with at least scattered
activity likely to enter interior southeast GA by the early
evening hours. Mesoscale boundary collisions should allow for a
few storms to pulse and become strong, with downburst winds of
40-50 mph, frequent lightning strikes, and heavy downpours being
the biggest threats into the evening. Brisk steering flow should
limit the threat for flooding rainfall, but "training" of
downpours repeatedly over the same locations is possible around
sunset for locations along and west of the I-75 corridor in the
Suwannee Valley and north central FL, where localized flooding
cannot be ruled out, especially at urban locations such as Ocala,
Gainesville, Live Oak and Lake City. Activity could get steered
back towards the I-95 corridor after sunset, especially for
locations north of St. Augustine. Maximum heat index values of
103-107 degrees are expected inland this afternoon.

Evening convection spreading into inland southeast GA and
potentially back towards the I-95 corridor to the north of St.
Augustine may linger through late this evening. Debris cloudiness
will then thin out overnight, with a light southerly low level
flow keeping low temperatures in the 70s inland, ranging to
around 80 at area beaches.

&&

.SHORT TERM...
(Friday through Saturday)
Issued at 248 PM EDT Thu Jul 17 2025

Initially moist southeasterly-southerly flow will shift to become
more westerly by the end of the week as high pressure ridging
extends in over towards the southeast. Daily bouts of diurnal
showers and thunderstorms will develop through the period, with
the majority of convection coverage occurring inland near the
areas of sea breeze convergence. High temperatures for the end of
the week and into the weekend are expected to rise into the upper
90s for inland areas and in the upper 80s and lower 90s along the
coastline. Overnight low temperatures will drop down into the mid
to upper 70s. Heat index values are expected to rise into Heat
Advisory levels on Friday and Saturday with heat index values
rising to values of 110 and higher.

&&

.LONG TERM...
(Sunday through next Thursday)
Issued at 214 PM EDT Thu Jul 17 2025

High pressure will move from east to west during this period,
resulting in a gradual shift in the prevailing flow to become
more out of the northwest by Monday. Pattern of daily bouts of
convection will continue through the long term period with
troughing situated to the northeast potentially developing into a
low pressure system would result in increased amounts of rainfall
by midweek with flow shifting to become more out of the northeast.
High temperatures through the weekend and into next week will be
above the seasonal average with max temps potentially reaching up
into the upper 90s and even the lower 100s for inland areas.
Potential for Heat Advisory conditions to continue through into
next week.

&&

.AVIATION...
(18Z TAFS)
Issued at 146 PM EDT Thu Jul 17 2025

Showers and a few thunderstorms developing along the Atlantic sea
breeze boundary near the I-95 corridor will shift inland this
afternoon and evening. Convection should increase in coverage as
it expands northwestward towards the GNV and VQQ terminals after
21Z. Confidence remains high enough to maintain TEMPO groups for
wind gusts up to 30 knots and IFR visibilities during heavier
downpours at GNV, while a TEMPO group for briefly gusty winds and
MVFR conditions was kept at VQQ. Activity may then shift north-
northeastward towards the Duval County terminals after sunset,
and confidence in this scenario remains high enough for PROB30
groups for briefly gusty winds and MVFR conditions during heavier
downpours to be maintained at JAX and CRG, while confidence was
only high enough for vicinity shower coverage at SSI and SGJ. VFR
conditions should then prevail by 03Z, with periods of MVFR to IFR
visibilities possible overnight at VQQ. Southeasterly surface
winds sustained at 10-15 knots at the SSI and SGJ coastal
terminals this afternoon will shift to southerly around 10 knots
after 00Z. Southerly surface winds elsewhere will remain sustained
around 10 knots through mid-afternoon before the Atlantic sea
breeze pushes inland, which will shift surface winds to
southeasterly. Surface winds will then shift back to southerly
towards sunset, with sustained speeds diminishing to 5 knots or
less at the inland terminals after 03Z.

&&

.MARINE...
Issued at 1206 PM EDT Thu Jul 17 2025

Atlantic high pressure centered near Bermuda will continue to
extend its axis westward across the Florida peninsula as weak low
pressure moves onshore along coastal Louisiana today. This high
pressure center will then shift westward towards the southeastern
seaboard on Friday and Saturday. Only isolated late afternoon and
evening thunderstorms are possible across the near shore waters
through Saturday. Troughing will then develop on Sunday over the
southeastern states on Sunday, with this feature potentially
sharpening near our local waters early next week. Chances for
showers and thunderstorms will increase beginning late Sunday
afternoon. Seas of 2 to 4 feet will prevail both near shore and
offshore during the next several days.

Rip Currents: A persistent east-southeasterly ocean swell will
combine with surf heights of 2-3 feet to create a lower end
moderate rip current risk at area beaches through Friday. A low
risk is currently anticipated this weekend and early next week.

&&

.FIRE WEATHER...
Issued at 1206 PM EDT Thu Jul 17 2025

Breezy southerly transport winds will combine with elevated
mixing heights to create good daytime dispersion values at most
inland locations. Breezy onshore surface winds developing at
coastal locations early this afternoon will keep daytime
dispersion values generally fair. Southerly transport winds will
weaken on Friday, resulting mostly in fair daytime dispersion
values, except good values across portions of inland southeast GA
due to elevated mixing heights. Transport winds will then shift to
southwesterly on Saturday, with light speeds resulting in mostly
poor daytime dispersion values for locations south of I-10, while
increasing speeds during the afternoon hours will combine with
elevated mixing heights across inland portions of southeast GA to
create good to marginally high daytime dispersion values.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  73  95  73  97 /  10  60  10  20
SSI  79  91  78  93 /  10  30   0  10
JAX  76  95  75  97 /  10  50   0  30
SGJ  76  92  75  93 /  10  40   0  20
GNV  73  95  74  97 /  40  50   0  40
OCF  74  94  75  95 /  40  50  10  40

&&

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

$$