876
FXUS62 KJAX 071631
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1231 PM EDT Sun Jul 7 2024

...New AVIATION...

.UPDATE...
Issued at 837 AM EDT Sun Jul 7 2024

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

Rest of Today...Light South to Southwest steering flow will
combine with a moist atmosphere (PWATs of 2 inches or more) across
all of NE FL/SE GA will support scattered to numerous thunderstorms
this afternoon and evening, mainly over inland areas as the East
Coast/Gulf Coast sea breezes should be able to push inland and
support the greatest coverage of storms between the US 301 and
I-75 corridors. The weak steering flow will support slow and
erratic storm motion around 10 mph or less and heavy rainfall will
remain the main storm threat with localized flooding concerns in
urban areas and other areas that have received recent heavy
rainfall. The delayed start to convection until the early to mid
afternoon hours will support Max temps into the lower to middle
90s and combining with dew points into the middle to upper 70s
will support peak heat indices into the 105-110 range and expect
pockets of Heat Advisory level readings of >= 108F, but likely not
enough to change the last shift`s decision to hold off with an
Advisory for today.

Tonight...Scattered to numerous slow moving storms are expected to
be ongoing over inland areas this evening with a slow drift back
towards the Atlantic Coast as they weaken due to the westerly mid
level winds. Activity should fade and slowly dissipate into
lingering shower activity towards midnight with isolated
convection possible after midnight due to leftover boundaries and
any untapped instability. Otherwise expect partly to mostly cloudy
skies from leftover mid and high convective debris cloudiness
which will keep warm and muggy conditions overnight with lows in
the mid/upper 70s inland and near 80 along the Atlantic Coast and
St. Johns River.

&&

.NEAR TERM...
Issued at 245 AM EDT Sun Jul 7 2024

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

Increasing rain chances and a gradual trend downward in max
temperatures today due to increased cloudiness and storminess as
high moisture content (precipitation water PWAT 2.2-2.5 inches)
stretches across SE GA in the vicinity of a diffuse but lingering
surface front. The mean layer 1000-500 mb ridge axis will shift
southward across NE FL into the afternoon, with more SW steering
flow (still weak around 5 kts) across SE GA which will push deeper
convection that develops inland slowly back toward the coast into
the early evening, bringing the Golden Isles higher rain chances
compared to the past couple of days.

The ridge axis across NE FL combined with PWAT of 1.9-2.2 inches
will promote sea breeze and airmass convection to develop & press
inland into the afternoon & evening, with boundary mergers focused
between I-75 and the Highway 301 corridor. Early morning
satellite continued to show upper level drier air across portions
of north-central FL, and this drier air under the mean layer ridge
will tend to limit convective coverage to scattered near our St.
Johns River basin counties with more limited vertical growth, with
the more numerous convection across the Suwannee River Valley of
NE FL.

The main storm hazard remains locally flooding rainfall, with the
entire area still under a "Marginal Risk" of flash flooding today
due to the highly saturated airmass and slow moving storms.
Hourly flash flood guidance is only 2-2.5 inches across parts of
SE GA, meaning that a lone slow moving storm cell with heavy
rainfall today on already saturated ground could cause road wash
outs, especially on secondary dirt roads. Gusty wet downbursts
will be possible, but with a continue of very warm mid levels,
severe strength gusty winds are not expected. Convection will
slowly fade with the loss of diurnal instability into the evening
hours, but a rouge shower or storm may form overnight given
lingering boundaries (outflows) under such a saturated airmass.

Max temperatures will begin to trend down across SE GA given
lingering debris clouds this morning and increased storminess into
the afternoon with highs reaching the lower 90s, while thinner
mid/high clouds across NE FL will enable temps to rise into the
mid to upper 90s before sea breezes and convective clouds/outflows
cool the low level airmass during afternoon. Peak heat index
values will generally near 100-105 degrees, and a heat advisory is
NOT planned for today. Tonight, muggy overnight low temperatures
will range in the low/mid 70s inland to upper 70s to near 80
toward the Atlantic coast.

&&

.SHORT TERM...
(Monday through Tuesday night)
Issued at 245 AM EDT Sun Jul 7 2024

Monday, above average moisture level and a weak pressure pattern
over the region as a cold front stays stalled over the deep south
states will allow both seabreezes to push inland with showers and
T`storms becoming numerous by afternoon most prominently near the
highway 301 corridor over NE FL and away from the coast in SE GA.
Mid level temperatures of -6 C, still a little warmer than the
average of -7 C, will largely preclude a threat for severe wet
downbursts winds and likely range 40-50 mph. But, locally heavy
rainfall, will be possible in many locations east of highway 301
where stronger storms should focus with 1-3 inch totals/isolated
4 inch amounts. Highs will be in the lower 90s at the coast and
low to mid 90s along and west of I-95. Peak heat index values will
range 105-108 with isolated higher values of 110 possible over NE
FL.

Monday night, convection will fade by midnight with the loss of
heating under mostly cloudy skies as debris clouds remain stubborn
to disperse. Lows will fall only into the middle to upper 70s for
most areas.

Tuesday, an approaching upper level wave will serve to add a bit
more lift as shortwave energy spirals in from the Atlantic waters
and numerous to widespread showers and T`storms will develop and
bring locally high rainfall totals over much of the area. The
surface high pressure ridge axis will stretch into south FL and
promote more west southwesterly flow in the low levels, keeping the
Atlantic seabreeze pinned near or just offshore Tuesday afternoon.
Highs will be near normal in the upper 80s to low 90s due to more
mid and high level cloud cover as the wave approaches.

&&

.LONG TERM...
(Wednesday through Saturday)
Issued at 245 AM EDT Sun Jul 7 2024

The forecast pattern will not change overall into next week as the
Bermuda high pressure ridge builds slowly northward to NE FL by
Friday and Saturday. Steering low level flow will be more from the
Southwest on Wednesday and Thursday as the ridge remains over the
southern half of the FL peninsula with a focus of storms closer to
I-95. The ridge axis will rise into central FL and then NE FL by
next weekend and shift the low level flow more southerly with
both seabreezes merging over the middle of the peninsula up into
SE GA along highway 301. Locally heavy rainfall, frequent lightning
and strong wet downbursts all possible in T`storms during the
period.

Temperatures will begin the period near normal Wednesday with highs
in the lower 90s and and then warm to above normal the rest of the
week as highs inland reach the mid 90s with isolated upper 90s
possible. Lows will be a little above normal in the mid to upper
70s.

&&

.AVIATION...
(18Z TAFS)
Issued at 1224 PM EDT Sun Jul 7 2024

Not much change expected for the upcoming TAF set as convection
has already kicked off west of all of the TAF sites and is
expected to drift slowly back towards the inland TAF sites of GNV,
VQQ and JAX through the afternoon/evening hours and will keep
current TEMPO groups going for potential MVFR CIGS/VSBYS, while
the East Coast sea breeze not looking very active at the moment
and the coastal TAF sites of CRG, SGJ and SSI should be able to be
held out with just VCTS or VCSH as most convection stays west of
the terminals or remains weak enough at this time. Convection
chances fade at terminals after sunset and mostly end by the 03Z
time frame with just lingering mid/high clouds through the
overnight hours which should keep fog chances to a minimum and
will continue to leave out of the forecast at this time. Any
rainfall chances on Monday morning appear too low to include or
will likely occur after the current TAF period ends at 18Z.

&&

.MARINE...
Issued at 245 AM EDT Sun Jul 7 2024

A surface front will linger across Georgia through mid-week as
surface high pressure extends across the Florida peninsula.
Southerly winds will prevail with daily sea breezes and mainly
afternoon and evening thunderstorms.

Rip Currents: Rip current assessments from near shore buoys
continued to indicate a solid Moderate risk for today for NE FL
and SE GA beaches with a E swell down to 0.5-1.0 ft with periods
9-10 seconds. A moderate rip current risk is expected Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  92  75  92  75 /  80  50  70  30
SSI  89  79  91  78 /  50  30  60  40
JAX  95  77  94  76 /  60  30  70  40
SGJ  93  78  93  77 /  40  20  70  40
GNV  95  75  93  74 /  60  40  70  20
OCF  95  76  93  75 /  50  50  70  30

&&

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

$$