109
FXUS62 KJAX 180756
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
356 AM EDT Tue Aug 18 2026

.KEY MESSAGES...

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

- Dangerously HOT Weather Continues through Friday. Extreme Heat
  Warnings and Heat Advisories are in Effect from 11 AM to 8 PM
  Today. Heat Advisories will Likely be Issued for Much of Our
  Area from Wednesday through Friday.

- Scattered to Numerous Afternoon and Evening Thunderstorms are
  Expected Across Northeast and North Central FL through
  Thursday. Strong Storms are Possible Each Day, Mainly Along
  the I-95 and I-10 Corridors.

- Afternoon and Evening Thunderstorm Coverage Increases During
  the Upcoming Weekend Area-Wide.


&&

.NEAR TERM /THROUGH TONIGHT/...
Main Highlights through Tonight:

- Dangerously Hot and Humid Weather Peaks in Intensity Today, with
Near Record High Temperatures Possible. Extreme Heat Warnings and
Heat Advisories are in Effect from 11 AM - 8 PM Today.

- Strong Thunderstorms Possible Late this Afternoon and Evening,
Mainly Across Northeast and North Central FL.

Early morning surface analysis depicts high pressure (1019
millibars) extending from the Bahamas westward across the FL
peninsula and through central portions of the Gulf. Meanwhile, a
frontal boundary extends from New England south-southwestward across
the Mid-Atlantic states and the Tennessee and lower Mississippi
Valleys. Aloft..."Heat Wave" ridging centered over northern Texas
continues to extend its axis southeastward along the northern Gulf
coast and through our area. A shortwave trough was riding the
northern periphery of this ridge across the Tennessee Valley.
Otherwise, deep troughing over Hudson Bay, Canada was digging slowly
southward across the Upper Midwest, Great Lakes, and New England.
Latest GOES-East derived Total Precipitable Water imagery indicates
that deep tropical moisture resides across most of our region, with
PWATs ranging from 1.9 - 2.2 inches. A slightly drier air mass was
advecting southeastward across eastern portions of GA, where PWAT
values just north of the Altamaha River were in the 1.6- 1.8 range.
Fair skies prevail throughout our region, with a light west-
southwesterly breeze keeping temperatures at 08Z in the upper 70s
and lower 80s nearly area-wide, with muggy dewpoints in the mid to
upper 70s.

"Heat Wave" ridging over Texas will begin to slowly retrograde
westward towards the Four Corners region of the Desert Southwest
later today and tonight, allowing a broad trough to gradually take
shape over the Deep South. West-northwesterly low and mid level flow
on the periphery of this ridge will advect a slightly drier air mass
into interior portions of southeast GA today, while deep tropical
moisture will prevail elsewhere downstream of a decelerating frontal
boundary that will be entering the southeastern states. This
slightly drier air mass should limit convective development for
locations from Waycross northward in southeast GA this afternoon,
and dewpoints falling to near 70 late in the afternoon as the drier
air mass mixes down to the surface. Plenty of sunshine will boost
highs to near 100 across most of southeast GA, with maximum heat
indices climbing to near 110 for interior southeast GA, where Heat
Advisories are in effect from 11 AM through 8 PM.

West-northwesterly low and mid level flow will delay the development
of the Atlantic sea breeze to the early to mid-afternoon hours at
coastal locations, with this boundary making slow progress towards
the I-95 corridor late this afternoon. Dewpoints rising to the mid
and upper 70s following the passage of the sea breeze should provide
for Extreme Heat Warning conditions across Glynn and Camden Counties
later this afternoon and evening, where heat index values could peak
near 115 degrees, prompting the issuance of Extreme Heat Warnings. The
deep tropical air mass over northeast and north central FL should
keep dewpoints in the mid to upper 70s, which will combine with
afternoon highs in the 95-100 degree range to create peak heat index
values of 113-115 degrees, prompting Extreme Heat Warnings from 11
AM - 8 PM.

Weak shortwave energy riding the periphery of the "Heat Wave" ridge
should enter our area late this afternoon and evening. Although
relatively mild temperatures aloft could temper storm intensity
somewhat, plenty of tropical moisture located across northeast and
north central FL should allow for scattered convection to develop
along mesoscale boundaries such as the inland moving Gulf and
Atlantic sea breezes during the mid and late afternoon hours.
Convection should increase in coverage and intensity late this
afternoon and early this evening across much of northeast and north
central FL as convective outflows and other mesoscale boundaries
collide, with a few storms pulsing and likely becoming at least
briefly strong, with wet microburst potential that could produce
wind gusts of 40-55 mph, along with frequent lightning strikes and
locally heavy downpours.

Shortwave energy entering out region late this afternoon and evening
could keep convection going well into the evening hours across
northeast and north central FL, with convective outflows potentially
igniting widely scattered convection during the early to mid evening
hours across southeast GA, generally for locations south and east of
Waycross. Convection should then dissipate towards or just after
midnight across our region, followed by debris cloud cover thinning
out during the predawn hours. Lows tonight should be slightly cooler
than what we are experiencing this morning, as values mostly fall to
the mid and upper 70s.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...

Main Highlights This Period (Wednesday and Thursday):

- Greatest chance for thunderstorms this period over NE FL
  during the afternoon and evening hours, with a few strong
  storms possible.

- Heat Advisories may be needed both Wednesday and Thursday.

An area of low pressure will be centered over the Carolinas this
period, with a cold front extending across southern GA. A weak
trough will extend south from it across region.

A prevailing flow from the west is expected Wednesday, with the
east coast sea breeze pushing to around the I95 corridor.
Drier air will advect into SE GA with the front. With the drier
air over SE GA, the greatest chance for convection will be over
southern portions of NE FL, especially closer to the east coast
sea breeze.

On Thursday, the prevailing low level flow will be from the
southwest and weaker, which will allow the east coast sea breeze
to push further inland. It will not be as dry over SE GA on
Thursday, so chances for convection will extend a little further
north. With the sea breeze moving further inland, the focus for
highest chances will also move further inland.

Temperatures will continue above average this period, and heat
advisories may be needed.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...

Main Highlights This Period (Friday through Monday):

- Near Record Heat and Dangerously High Heat Indices Continue on
  Thursday and Friday.

- Scattered to Numerous Afternoon and Evening Thunderstorms Each
  Day from Friday through the Upcoming Weekend

An area of low pressure will remain over the Carolinas this
period, with a frontal boundary extending southwest from it.
This front is expected to largely stay north of SE GA this
period. A high pressure ridge will extend across south FL.

This pattern will result in a prevailing flow from the
southwest. With this flow, the east coast sea breeze will have
a hard time making it much further inland than the I95
corridor.

An upper trough will be over the region throughout this period,
with waves moves through it. The upper energy will help to
create greater instability over the area. The strongest upper
wave moves through Saturday, which is when the greatest chance
for convection is forecast.

Temperatures will be near to a little above average this period.

&&

.AVIATION /06Z TUESDAY THROUGH 06Z WEDNESDAY/...

VFR conditions will prevail at the regional terminals through at
least 20Z. Showers and thunderstorms are expected to increase in
coverage and intensity near the northeast FL terminals after
20Z through around 02Z. We have maintained PROB30 groups for the
time being at the northeast FL terminals, featuring brief
surface wind gusts up to 30 knots and IFR visibilities during
heavier downpours. Confidence in convective coverage across
southeast GA on Tuesday afternoon and evening remains too low to
include anything other than vicinity thunderstorm coverage at
this time. Convection may linger through around 03Z Wednesday at
the northeast FL terminals, with VFR conditions then expected
to prevail towards the end of the TAF period. West-southwesterly
surface winds sustained at 5-10 knots overnight will shift to
westerly, increasing to 10-15 knots before 15Z. The Atlantic sea
breeze will likely not move onshore until after 18Z, with the
passage of this boundary shifting surface winds to southeasterly
at SGJ and southerly at SSI. Surface winds will then shift to
southwesterly at 5-10 knots towards 04Z at the regional
terminals following the conclusion of evening convection.

&&

.MARINE...

High pressure extending from the Bahamas westward across the
Gulf will gradually weaken this week as a frontal boundary
sags southward over the southeastern states. Westerly winds will
prevail during the next several days, with winds over the near
shore waters shifting to southerly and increasing during the
afternoon and evening hours as the Atlantic sea breeze shifts
slowly inland. Coverage of afternoon and evening showers and
thunderstorms will increase late this afternoon and evening,
mainly across the northeast Florida waters. Scattered to
numerous afternoon and evening thunderstorms will mostly be
confined to the northeast Florida waters on Wednesday and
Thursday, followed by coverage gradually increasing across the
Georgia waters from Friday through the upcoming weekend as the
frontal boundary stalls near our area.

Rip Currents: Prevailing offshore winds and low surf heights
will keep a low risk in place through at least midweek at area
beaches. Offshore winds will decrease slightly by Thursday and
Friday, allowing the afternoon sea breeze to create breezy
onshore winds that may result in a lower end moderate risk at
the northeast FL beaches on Thursday and Friday.

&&

.FIRE WEATHER...

- Heat Advisories And Extreme Heat Warnings In Effect Today.

- Patchy High Daytime Dispersions SE GA Today And Wednesday.

The region will be between high pressure to the south, and a
frontal zone to the north this period. Thunderstorms will be
in the forecast each afternoon and evening this period. The
highest chance for storms will be on Saturday. It will be an
abnormally hot week, with readings returning to more seasonal
levels over the weekend.

Fog Potential: Significant fog formation is not expected. Gusty
and erratic winds are possible within stronger thunderstorms.

&&

.CLIMATE...
Near record high temperatures are possible at some of our
designated climate sites during the next several days:

Tuesday, August 18:
KJAX: 98/1954
KGNV: 98/1954
KAMG: 105/1995
KCRG: 96/2023

Wednesday, August 19th:
KJAX: 99/1900
KGNV: 100/1954
KAMG: 103/1995
KCRG: 97/2010

Thursday, August 20th:
KJAX: 101/1900
KGNV: 99/1900
KAMG: 104/1995
KCRG: 98/2016

Friday, August 21st:
KJAX: 101/1900
KGNV: 99/1983
KAMG: 100/1980
KCRG: 99/2016

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  99  76  99  74 /  20  20  10   0
SSI  99  78  97  80 /  40  20  10   0
JAX  98  76  97  76 /  60  30  40  10
SGJ  97  78  96  77 /  60  30  50  10
GNV  95  76  95  75 /  60  40  60  20
OCF  94  77  96  76 /  50  50  70  10

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Extreme Heat Warning from 11 AM this morning to 8 PM EDT this
     evening for FLZ021-023-024-030-031-035-038-120-124-125-
     132-136>138-140-220-225-232-233-236-237-240-322-325-333-
     340-422-425-433-522-533-633.
GA...Extreme Heat Warning from 11 AM this morning to 8 PM EDT this
     evening for GAZ153-154-162-165-166.
     Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for GAZ132>136-149-151-152-163-250-264-350-364.
MARINE...None.

&&

$$