887
FXUS62 KJAX 181122
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
722 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 this Week. Extreme Heat
  Warning and Heat Advisories Today from 11 AM 8 PM. Heat Index
  Values Peak in the 108-115 F Range this Afternoon. Heat
  Advisories & Extreme Heat Warnings Possible Wednesday through
  Friday

- Scattered to Numerous TStorms Each Afternoon & Evening through
  Sunday. Main Impact Areas through Thursday: Northeast and
  North Central FL. Strong Storms are Possible Each Day, Mainly
  Along the I-95 Corridor. Primary Hazards: Wind Gusts of 40-55
  mph, Frequent Lightning Strikes, and Heavy Downpours

&&

.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 /12Z TUESDAY THROUGH 12Z WEDNESDAY/...
VFR conditions will prevail at the regional terminals through at
least 18Z. Showers and thunderstorms are expected to increase in
coverage and intensity near the northeast FL terminals after 18Z
through around 02Z. Have PROB30/TEMPO groups at the northeast FL
terminals to account for brief gusts up to 30 knots and IFR
visibilities during heavier downpours. Confidence in convective
coverage across southeast GA this afternoon and evening remains too
low to include anything other than vicinity shower coverage at this
time. Convection may linger through around 02Z Wednesday at the
northeast FL terminals, with VFR conditions then expected overnight.
Westerly winds 5-10 kts prevail today outside of storms. The
Atlantic sea breeze will likely not move onshore until after 18Z,
with the passage of this boundary shifting surface winds to south-
southwesterly at SGJ and SSI.

&&

.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 couple of 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 later
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  98  77  99  74 /  20  20  10   0
SSI  97  80  97  80 /  20  10  10   0
JAX  98  78  97  76 /  50  30  40  10
SGJ  96  79  96  77 /  60  20  50  10
GNV  96  78  95  75 /  50  30  60  20
OCF  95  78  96  76 /  40  30  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.

&&

$$