401
FXUS62 KJAX 050805
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
405 AM EDT Fri Jul 5 2024

...HEAT ADVISORY TODAY INLAND ZONES...

...New NEAR TERM, SHORT TERM, LONG TERM, MARINE, CLIMATE...

.NEAR TERM...
Issued at 345 AM EDT Fri Jul 5 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

Heat Advisory today for inland zones (generally west of the
Highway 301 corridor) where afternoon peak heat index values near
110 degrees before slow moving scattered to numerous afternoon
showers and thunderstorms briefly bring some cooler temperatures
with convective outflows. Farther toward the Atlantic coast,
satellite derived precipitable water (PWAT) indicated values of <
1.6 inches advancing SSW across coastal SE GA and approaching the
NE FL coast, while deeper PWAT of > 2 inches continued across our
inland zones. The main difference in the weather today will be a
downward trend in coastal rain chances compared to recent days
given the intrusion of drier air from the east, while the higher
rain chances will focus inland through the afternoon and evening
hours. Very weak 700-1000 mb steering flow < 5 kts will bring the
threat of locally heavy rainfall as boundaries merge and resultant
storms linger with slow, erratic drifting into the early evening
as diurnal instability fades. Not much mid or upper level dynamics
or instability to favor severe storm potential today.
Precipitation will fade inland through midnight, trailed by dry
conditions and ground fog through daybreak Saturday.

High temperatures will range above normal from the low 90s coast
to mid 90s inland. Muggy overnight low temperatures will range in
the mid to upper 70s.

&&

.SHORT TERM...
(Saturday through Sunday night)
Issued at 345 AM EDT Fri Jul 5 2024

Saturday, a cold front will slowly approach the area and help to
bring above normal moisture levels back across Atlantic coast with
a weak pressure pattern allowing the Atlantic and Gulf coast
seabreezes to move inland and merge near highway 301. With warm
mid level temperatures, not expecting severe T`storms, but high
PWAT values over the 90th percentile will promote very efficient
rainfall rates with slow storm motion due to mid to upper level
ridging over the eastern Gulf adjacent to the FL peninsula
allowing for localized heavy rainfall amounts of 1-3 inches
which may lead to minor flooding in urban and low lying areas.
Strong wind gust potential will T`storms along with frequent
lightning. Light east to southeast winds 5-10 mph will move
onshore behind the Atlantic seabreeze with light SW winds behind
the Gulf seabreeze. Highs will rise into the mid 90s away from
the coast with low 90s at the beaches. Heat index values will
be in the 105-110 degree range near heat advisory levels.

Saturday night, T`storms should end by midnight inland with very
light southerly winds turning near calm well after sunset. Multi
level cloud cover from fading T`storms will slowly disperse
overnight to partly cloudy skies. Lows will be in the mid 70s
inland and the upper 70s to near 80 at the coast.

Sunday will feature similar conditions with the cold front a
bit closer, extending into southern GA, but should be stopped
from further progress due to the mid to upper level ridging over
the eastern Gulf/FL peninsula. With the weak surface pressure
gradient, both seabreezes should merge inland with locally heavy
rainfall creating potential localized flooding concerns due to
the high moisture content and slow storm motions. Highs will be
a only a degree or two lower compared to Saturday due to more
numerous to widespread T`storm coverage and mostly cloudy skies
in the afternoon/early evening hours with low to mid 90s inland
and around 90 at the coast. Heat index values will range 104-108
degrees, again nearing heat advisory criteria.


&&

.LONG TERM...
(Monday through Thursday)
Issued at 345 AM EDT Fri Jul 5 2024

Not much change in the forecast pattern into next week as mid to
upper level ridging remains entrenched from the central Gulf coast
into the coastal SE. Bermuda high pressure ridging will build into
South FL and bring more southwesterly weak low level steering over
the area, focusing the highest coverage of T`storms to the I-95
corridor as the Gulf seabreeze progresses towards the east coast
before merging with the pinned Atlantic seabreeze with locally
heavy rainfall, frequent lightning, and some strong wind gusts
from wet downbursts.

Temperatures will begin the period near normal Monday and Tuesday
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 not out of the question. Lows will be a little
above normal in the low to mid 70s inland and the upper 70s to
near 80 at the immediate coast and St Johns river basin.

&&

.AVIATION...
(06Z TAFS)
Issued at 136 AM EDT Fri Jul 5 2024

The combination of shallow ground fog from recent rainfall after
sunset and smoke due from evening fireworks created early MVFR to
IFR restrictions at CRG, VQQ and JAX...with a transient low
ceiling deck recently reported at SSI. Best potential for IFR to
LIFR will continue at VQQ through sunrise with MVFR at JAX. Muggy
overnight conditions will bring hazy skies to other terminals with
rain free conditions through 14z and light to near calm winds
inland with a weak land breeze SSW 4-6 kts expected at coastal
terminals under passing mid level debris clouds.

Rain chances increase across inland terminals 16-18z with airmass
convection popping between slow moving, inland progressing sea
breezes. VCSH was indicated for coastal terminals 18-19z, with the
best chances of TS focused toward VQQ and GNV 17-20z where higher
rain chances are expected. Convection will be slow moving and
erratic in motion given weak steering flow, with precipitation
gradually fading across inland zones 23-03z with clearing skies at
coastal terminals through 00z and SE winds trailing the east
coast sea breeze.

Rainfall will tapper off through 06z with winds becoming light and
variable under lingering debris clouds.

&&

.MARINE...
Issued at 345 AM EDT Fri Jul 5 2024

High pressure will extend across north Florida today and tonight
as a frontal boundary shifts southward across Georgia. Sea breezes
will move inland this afternoon from both the Gulf and Atlantic
coasts. Saturday, the front will shift across south Georgia and
linger through mid-week next week, with an increase in mainly
afternoon and evening thunderstorms and continued southerly winds.

Rip Currents: Rip current assessments from near shore buoys
indicated a solid Moderate risk for today for all NE FL and SE GA
beaches with a continued ESE swell of 1-2 ft but with periods now
9-10 seconds compared to 12-13 seconds yesterday. A moderate rip
current risk is expected through the weekend.

&&

.CLIMATE...
Issued at 400 AM EDT Thu Jul 4 2024

Above average max/min temps are expected through Saturday with
the record high minimums not too far off the forecast min temps in
the mid 70s. Below are some record high minimum temperatures that
may be challenged for select climate sites:

July 5:
KGNV: 75/2023

July 6:
KJAX: 79/1902
KGNV: 78/1900

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  94  75  94  75 /  60  30  60  30
SSI  91  79  91  79 /  10  10  40  20
JAX  95  76  94  76 /  40  10  60  20
SGJ  92  77  92  77 /  30  10  50  20
GNV  93  74  94  73 /  80  40  60  20
OCF  94  75  93  76 /  80  40  60  20

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for FLZ021-023-030-031-035-120-136-140-220-236-240-322-340-
     422-522.

GA...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for GAZ132>134-149-162-163-250-350-364.

AM...None.
&&

$$