359
FXUS62 KJAX 011624
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1224 PM EDT Mon Jul 1 2024

...STRONG STORMS AND HEAVY DOWNPOURS POSSIBLE THIS AFTERNOON AND
EVENING...
...WIDESPREAD DOWNPOURS AND LOCALIZED FLOODING POSSIBLE ON TUESDAY
AFTERNOON AND EVENING...
...DANGEROUS HEAT INDICES POSSIBLE FRIDAY THROUGH THE UPCOMING
WEEKEND...

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

.UPDATE...
Issued at 1224 PM EDT Mon Jul 1 2024

Noon surface analysis depicts a cold front stretching from the
Ozarks eastward to the Carolinas that is decelerating as it pushes
into the Deep South. Meanwhile, strong high pressure (1030
millibars) was building over the Great Lakes region in the wake of
this frontal boundary. Aloft..."Heat Wave" ridging remains
centered along the Red River Valley of northern Texas, with this
feature continuing to expand into the southeastern states.
Otherwise, troughing was progressing southeastward towards the
Mid-Atlantic states and coastal New England. Latest GOES-East
derived Total Precipitable Water imagery indicates that deep
tropical moisture prevails throughout our region, with PWATS
generally in the 2 - 2.2 inch range, except for north central FL,
where values were in the 1.8 - 2 inch range. Slow moving, low-
topped showers were developing within this very humid air mass
along portions of the U.S. Highway 301 corridor in southeast GA,
while convection developing along the Gulf coast sea breeze along
the FL Big Bend and Nature Coasts remains nearly stationary over
Levy and Dixie Counties, while showers were developing ahead of
this sea breeze boundary across southern portions of the Suwannee
Valley early this afternoon. Temperatures at 16Z were mostly in
the low to mid 80s across southeast GA, with values rising to the
85-90 degree range elsewhere for northeast and north central FL.
Dewpoints were in the mid to upper 70s at most locations.

Our area will remain within a col region aloft during this
afternoon as "Heat Wave" ridging remains centered to the west of
our area and troughing progresses southeastward and offshore of
the Mid-Atlantic and New England coasts. The frontal boundary will
get pushed southward across the Altamaha River this evening before
support aloft wanes, as troughing exits into the Atlantic and
ridging aloft nudges eastward over the Lower Mississippi Valley.
Light winds within the aforementioned col region overhead will
result in slow moving downpours developing this afternoon, with
activity likely developing along a lingering low level trough that
is situated along U.S. Highway 84 in southeast GA, with additional
scattered convection being generated by the inland moving Atlantic
and Gulf sea breeze boundaries. Short-term, high resolution model
guidance continues to target the U.S. Highway 301 corridor in
southeast GA for excessive rainfall potential, where a quick 2-4
inches with locally higher totals will be possible in a corridor
from Nahunta and Blackshear northeastward to Jesup and Darien
through this evening. Mesoscale boundary collisions may shift
another axis of heavy downpours southward along the I-10 and I-75
corridors through the evening hours, where a widespread 1-2 inches
with locally higher amounts will be possible for locations such as
Macclenny, Lake City, Live Oak, and Gainesville. Some of this
activity will attempt to shift towards the I-95 corridor after
sunset before waning towards midnight.

The morning sounding at Jacksonville revealed a steep lapse rate
in the mid-levels, with a pocket of mild and dry air above this
layer. Strong to isolated severe thunderstorms will be possible
this afternoon through early this evening, with wet microbursts
potentially bringing wind gusts up to the 40-60 mph range, along
with frequent lightning strikes and slow moving downpours. High
temperatures will generally climb to the lower 90s this afternoon
before thunderstorm coverage increases. Convective coverage will
diminish towards midnight, with debris cloudiness thinning out
overnight across northeast and north central FL, while low
stratus clouds likely develop during the predawn and early morning
hours along the stalling frontal boundary across southeast GA.
Lows tonight will generally fall to the mid 70s inland and the
upper 70s at coastal locations.

&&

.SHORT TERM...
(Tuesday through Wednesday night)
Issued at 400 AM EDT Mon Jul 1 2024

Pattern of scattered to numerous showers and storms will continue
through midweek as the weakening frontal boundary stalls to the
north over Georgia. Thunderstorms will be capable of producing heavy
rains with a potential for localized flooding as PWAT values ahead
of the frontal boundary will measure between about 2.2 to 2.6 inches
through midweek. High temperatures for this period will be in the
90s for most inland areas and in the upper 80s along the coast and
for inland areas of southeast Georgia north of Waycross. Overnight
low temperatures will drop down into the mid 70s over inland areas
and in the upper 70s along the coastline. Heat advisory conditions
may be possible on Tuesday and Wednesday as heat index levels rise
to 108 and above during peak daytime heating.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 400 AM EDT Mon Jul 1 2024

Diurnal convection will become less widespread By Thursday and
Friday as high pressure situated to the northeast acts to draw drier
air over the forecast area from out of the north. Models currently
show some disparity as to the placement of drier air by the end of
the weekend, with a potential for more widespread diurnal convective
developments on Sunday. Daily high temperatures will rise to near
record high temperatures during the latter part of the week and into
the weekend, with heat index values expected to reach Heat Advisory
levels through the end of the period.

&&

.AVIATION...
(12Z TAFS)
Issued at 630 AM EDT Mon Jul 1 2024

MVFR and IFR ceilings are expected to persist off and on through
the morning hours with showers and storms building in by around
18-19z today. Potential for strong to severe storms forming over
SE GA and NE FL today with storms capable of producing heavy
localized rainfall. Convection will become more dispersed for most
sites by around 01-02z however overnight storms are possible,
however low ceilings and vicinity thunderstorms may persist for
SSI through into Tuesday morning.

&&

.MARINE...
Issued at 1224 PM EDT Mon Jul 1 2024

A frontal boundary will approach our local waters from the north
through tonight. Breezy south to southwest winds will prevail
ahead of this approaching frontal boundary through tonight. The
frontal boundary will stall over the Georgia waters on Tuesday and
dissipate, with increasing chances for mainly afternoon and nighttime
showers and thunderstorms across our local waters. Prevailing winds
will shift to east and southeast beginning on Tuesday through Wednesday
as high pressure builds down the southeastern seaboard. Seas of
2-4 feet will prevail both near shore and offshore during the next
several days. High pressure will then weaken as it shifts
southward towards our local waters later this week.

Rip Currents: Onshore winds developing in the wake of the inland
moving Atlantic sea breeze will combine with a persistent, long
period easterly ocean swell to create a lower end moderate rip
current risk at all area beaches through at least Tuesday.

&&

.FIRE WEATHER...
Issued at 1224 PM EDT Mon Jul 1 2024

Breezy southwesterly transport winds for locations along and south
of Interstate 10 this afternoon will create fair to good daytime
dispersion values. Lighter east to southeasterly transport winds
across inland southeast GA will result in generally poor daytime
dispersion values. Breezy onshore surface winds will develop in
the wake of the Atlantic sea breeze this afternoon along the
I-95 corridor. Transport winds will shift to southerly for
locations along and south of I-10 on Tuesday, with light speeds
generally resulting in fair daytime dispersion values, while
easterly transport winds across southeast GA create poor to fair
daytime dispersion values. Surface and transport winds will then
shift to east-southeasterly area-wide on Wednesday, with fair
daytime dispersion values forecast by the afternoon hours at most
locations.

&&

.HYDROLOGY...
Issued at 400 AM EDT Mon Jul 1 2024

Deep tropical moisture over the region will lead to heavy downpours
from convection especially along and ahead of an approaching frontal
boundary/trough from the north. WPC has placed SE GA in a slight
risk of excessive rainfall today. Localized areas could see rain
amounts of 3 inches, with higher amounts of 5 inches possible. A
Flood Watch was introduced for a few southeast GA counties for
this threat. Refinements to the watch may be needed later today.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  92  74  88  73 /  70  60  60  40
SSI  90  79  86  78 /  50  50  60  40
JAX  92  75  91  74 /  70  60  70  40
SGJ  91  77  90  77 /  40  40  50  30
GNV  91  74  92  74 /  70  50  60  40
OCF  91  74  92  75 /  70  40  60  30

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...Flood Watch until 10 PM EDT this evening for GAZ136-151>153.

AM...None.
&&

$$