147
FXUS62 KJAX 210523
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
123 AM EDT Tue Jul 21 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

- Widely Scattered thunderstorms today. Isolated strong storms
  will be capable of strong gusts in the 40-60 mph range.

- Moderate Rip Current Risk Today and Wednesday

- Small Craft Advisory Conditions this afternoon and evening.

&&

.NEAR TERM /THROUGH TONIGHT/...

- Seasonably Hot Summer Conditions
- Isolated strong storms capable of strong outflow wind gusts
  this afternoon

Overall, a similar strong southerly flow pattern will be in place
again today between westward moving Tropical Storm Bertha in the
northern Gulf and the western extension of the Bermuda ridge. A dry
air intrusion in the mid to lower levels will lead to a sharp
reduction in coverage this afternoon with generally isolated to
scattered thunderstorms developing through the afternoon hours.

With precipitable water falling between the 10th and 25th percentile
and only marginally sufficient mid level lapse rates, the threat of
severe convection will be dampened. However, the prevailing
southerly flow around 20-25 mph and the potential for strong
downbursts (DCAPE > 1000 j/kg) will exist even with marginal
convective developments. Available instability will be a limiting
factor but outflow sea breeze convergence during the mid to late
afternoon may be enough to overcome it, allowing a few strong pulses
to develop. If (a big "if") strong convection can mature, the
resulting downbursts will drop into steep near-surface lapse rates
and may lead to localized gusts up to 60 mph.

Temperatures will again be seasonably hot as highs push toward the
mid 90s this afternoon. Heat index will push well into the 102-108
degree range today and may flirt with Heat Advisory levels along the
immediate coast as dewpoints rise with the sea breeze. Due to the
very localized nature, elected to continue without adding any heat-
related headlines this morning.

Though a few showers may linger after the sun sets, the bulk of the
diurnal convection will fade quickly with the loss of heating. While
low level flow remains elevated, overnight low temperatures will
again be above normal general in the mid 70s inland and upper 70s
at the coast.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Main Highlights This Period:

- Drier conditions on Wednesday
- Isolated to Widely Scattered Thunderstorms return Thursday
  Afternoon

Wednesday, high pressure ridging will work back eastward over the FL
peninsula as Tropical Storm Bertha shifts further west over the
northern Gulf waters near the central Gulf coast. Drier air in the
low/mid levels will linger over the area as Bertha moves further
away and will greatly reduce pops leading to a dry day along the
coast and only widely isolated thunderstorms west of US-441/221 in
SE GA and west of the Suwannee River in NE FL.

Southerly winds will become more south southwesterly during the
afternoon as surface high pressure surface ridge axis extends into
central FL and breezy 10-15 mph with gusts to 20-25 mph with the
elevated pressure gradient. Breezy winds and partly cloudy skies
will allow highs to reach the mid 90s for most of the area except
the Suwannee valley where onshore flow from the Gulf will limit
highs to the low 90s there and along the immediate coast. Dewpoints
mixing out to around 70 north of I-10 and low 70s over NE FL will
limit heat index values to 100-104 and 102-106 along the coast where
dewpoints stay in the mid 70s.

Thursday, moisture levels will increase to near normal as a cold
front sinks south of the TN valley into northern GA with a return of
isolated to widely scattered thunderstorms across SE GA and isolated
storms along the Atlantic seabreeze moving into the I-95 corridor in
the afternoon and just past US-17 corridor by late afternoon.
Similar highs are expected in the mid 90s with low 90s at the coast
and Suwannee Valley behind the Advancing seabreezes.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Main Highlights This Period:

- Scattered to Numerous Afternoon Thunderstorms, Especially
  Friday into the Weekend
- Potential Heat Advisory Conditions Late Week & Weekend

The cold front will stall north of the area near central GA Friday
with weak SW flow and moisture levels increasing above normal with
support scattered thunderstorm chances across SE GA and less chances
further south away from the front.

Shortwave energy shifting ESE across the southern Appalachians to
the Carolina coast will help amplify a trough over the Mid Atlantic
and southeast coast, and will allow the front will sink into SE GA
Saturday and then sink into NE FL Sunday where it will stall into
Monday. The front will bring increasing chances for showers and
thunderstorms with numerous thunderstorms across SE GA Sunday and
portions of NE FL on Monday. West to WSW flow will become a bit
breezier late this weekend as a low develops near the NC coast on
Sunday and lifts away to the NE on Monday.

Highs during the period will be above normal in the mid 90s Friday
and Saturday, with low 90s on Sunday due to more clouds from the
front and low to mid 90s Monday with more partly cloudy skies. Heat
index values will approach heat advisory levels by this weekend into
Monday as dewpoints remain in the mid to upper 70s each afternoon
with values 104-108.

&&

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

VFR conditions will be the prevailing sky condition outside of
shower/thunderstorm occurrences today. Convection will be stunted by
incoming dry air aloft but isolated to scattered thunderstorms are
still possible at area terminals. Due to the decreased coverage, the
forecast still keeps potential for terminal impacts due to storms
around 20-40% through 18z-00z this afternoon and evening. Southerly
winds will increase again, becoming gusty after 15z, with peak gusts
around 20-25 knots. Winds will slacken during the early evening and
fall to around 5-10 knots still out of the south to south-
southeasterly direction.

Given the dry air aloft, in the slim chance scenario of robust
convection developing in vicinity of terminal airspace (about 10
miles) there will be potential for strong localized wind gusts in
excess of 35 knots produced by downbursts.

&&

.MARINE...

Breezy southerly winds between the tropical storm Bertha and the
Bermuda high will lead a couple more days of breezy conditions.
Winds will increase to Small Craft Advisory levels this afternoon
and remain elevated through early Wednesday. Seas will rise toward 5
or possibly 6 feet today in response to the winds. Relaxing winds
are expected Wednesday night as flow generally trends offshore as a
weak cold front approaches from the northwest. The front is likely
to  stalls north of the waters this weekend as waves of low pressure
track along it. Though offshore flow will be in place from Thursday
onward, afternoon winds in nearshore waters will be driven by the
coastal sea breeze development each afternoon.

Rip Currents:

Increasing southerly winds along with sea breeze development will
push elevated wind waves into the coastline this afternoon along
with strong longshore. Given a minimal onshore swell, the rip
current risk will be on the upper-end of Moderate this afternoon but
not quite High Risk. Moderate risk is likely again Wednesday before
falling Thursday.

&&

.FIRE WEATHER...

Tropical Storm Bertha will move slowly westward away from the area
today across over the northern Gulf waters with breezy southerly
winds 15-20 mph and gusts to 25-30 mph. Atlantic seabreeze will move
slowly onshore only to I-95 by mid afternoon. Scattered showers will
lift from the Gulf coast over the Suwannee Valley into western
Southeast Georgia late this morning with scattered afternoon storms.
A few storms may be strong with gusty and erratic winds as they move
quickly northward. Mainly dry conditions expected on Wednesday as
surface high builds over the Florida peninsula with breezy southerly
winds continuing. A frontal boundary will approach on Thursday with
isolated to scattered thunderstorms during the afternoon hours
through Friday. Increasing thunderstorm chances expected this
weekend as the front sinks into the area.

Breezy surface and transport winds today and Wednesday will create
areas of high dispersions across the area each day away from the
coast.

Fog Potential and Other Remarks: Significant fog development is not
expected for the next several nights. No significant impacts
expected from Tropical Storm Bertha.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  93  75  94  75 /  40  10  10  10
SSI  93  81  94  80 /  20  10  10  10
JAX  95  77  96  76 /  20  10  10   0
SGJ  94  77  95  76 /  20  10  10   0
GNV  93  75  94  74 /  40   0  10   0
OCF  93  75  94  75 /  40  10  10   0

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to 5 AM EDT
     Wednesday for AMZ450-452-454-470-472-474.

&&

$$