-- Discussion containing changed information from previous version are highlighted. --
772
FXUS62 KJAX 291731
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
131 PM EDT Mon Apr 29 2024

...New AVIATION...

.UPDATE...
Issued at 935 AM EDT Mon Apr 29 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

High pressure system continues at 9 AM across the Carolinas at
about 1023 mb with prevailing southeast low level flow over our
local area. Water vapor imagery and GFS analysis shows mid level
ridge over the region with a weak mid level trough over the
northeast GOMEX. Both of these features aloft will shift eastward
through tonight. The 12z JAX sounding shows the dry airmass with
PWAT of 0.73 inches and a strong subsidence inversion at about 860
mb. Vis imagery shows some mostly cloudy skies across a good
portion of southeast GA, likely associated with some isentropic
ascent at about 4-5 kft. Believe these skies will tend to diminish
through the last morning. Otherwise, some diurnal cumulus expected
rest of today. For the update, forecast looked on track with just
some tweaks to the initial sky condition. Still seems possible a
few showers possible late aftn over the I-75 corridor over
northeast FL where collision of the sea breezes would occur. Just
some a slight adjustment to lower POPs there a bit based on
guidance.

&&

.SYNOPSIS...
Issued at 411 AM EDT Mon Apr 29 2024

Early morning surface analysis depicts weakening high pressure
(1023 millibars) centered over the Gulf Stream waters adjacent to
the Carolinas. Meanwhile, a wavy frontal boundary extends from the
Great Lakes region across the Upper Midwest and then southwestward
across the Southern Plains states. Aloft...ridging remains
centered along the southeastern seaboard, with a broad trough
progressing slowly eastward across the Rockies and the Plains
States. Ridging in place across our region was deflecting a potent
shortwave trough northeastward from the High Plains towards the
upper Midwest, while a more subtle shortwave trough was emerging
from the lee side of the Rockies and was progressing eastward
towards the Southern Plains States. Multi-layered cloud cover
continues overhead from locations along and north of Interstate
10, as pockets of marine stratocumulus continue to advect onshore
from the Atlantic waters, while a weak shortwave trough drifting
near the FL panhandle coast continues to generate high altitude
cloudiness. Fair skies otherwise prevail across north central FL,
where radiational cooling was dropping temperatures into the upper
50s and lower 60s as of 08Z. Otherwise, breezy onshore winds along
the Atlantic coastal communities were keeping temperatures in the
upper 60s and lower 70s. Dewpoints ranged from the mid and upper
50s at most inland locations to around 60 at coastal locations.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 411 AM EDT Mon Apr 29 2024

High pressure off the southeastern seaboard will gradually weaken
as it shifts eastward this afternoon and tonight. This feature
will maintain breezy onshore winds today at coastal locations,
with the Atlantic sea breeze boundary progressing quickly inland
this afternoon. The Atlantic and Gulf coast sea breezes will
collide to the west of Interstate 75 towards sunset, and just
enough moisture may be available (PWATs rising to around 1 inch)
for isolated to widely scattered showers to develop around or just
after sunset between the Suwannee River and I-75, generally for
locations south of Live Oak and Lake City. Any showers that manage
to develop along this sea breeze collision this evening will
dissipate before midnight, and moisture depth will be too shallow
for thunderstorm development. Otherwise, a gradual warming trend
will commence today as less in the way of marine stratocumulus
moves inland, allowing highs to climb to the mid 80s at most
inland locations, except upper 80s for north central FL. Breezy
onshore winds will keep coastal highs closer to 80.

The subtle shortwave trough currently progressing towards the
Southern Plains states this morning will amplify tonight as it
traverses the lower Mississippi Valley, driving a weakening
frontal boundary towards the southeastern states by early Tuesday
morning. This feature will shift our low level flow to southerly
tonight, with elevated speeds in the boundary layer likely
preventing significant fog formation overnight. Thin cirrus will
begin to spill into our region after midnight, with warm air
advection ahead of the approaching shortwave keeping lows in the
60s area-wide.

&&

.SHORT TERM...
(Tuesday through Wednesday night)
Issued at 411 AM EDT Mon Apr 29 2024

Surface high pressure off the FL/GA coasts will gradually shift
further into the Atlantic through mid-week. On Tuesday, a
weakening shortwave trough will pass through the SE US providing
some forcing for ascent. Southerly flow will allow for moisture to
rebound with PWATs increasing to around 1.2 to 1.4 inches. This
should be enough moisture to support showers and storms moving
into inland SE GA and developing along the afternoon sea breezes
Tuesday afternoon into evening.

Flow shifts to west-southwesterly on Wednesday, keeping the
Atlantic sea breeze pinned between US-17 and I-95. Lingering
moisture will support isolated showers developing along the
Atlantic sea breeze Wednesday afternoon. Daytime highs will be in
the mid to high 80s with overnight lows in the 60s.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 411 AM EDT Mon Apr 29 2024

Drier air will filter in as surface high pressure builds down from
the Mid Atlantic states and ridging aloft builds back over the SE
US Thursday into Friday. The diurnal sea breezes slowly shift
inland each day but dry air aloft will hinder showers developing
along the boundaries.

Friday night into the weekend, easterly flow will gradually veer
to southerly as a cold front nearly stalls across the deep south,
ushering moisture back across the region. This will bring a
return of isolated showers and T`storms over SE GA for the
weekend. Above normal temperatures expected with highs rising
into the upper 80s/low 90s and overnight lows in the 60s.

&&

.AVIATION...
-- Changed Discussion --
(18Z TAFS)
Issued at 128 PM EDT Mon Apr 29 2024

VFR will continue to dominate through early Tuesday afternoon. Mainly
few-sct cumulus this afternoon at 4-5 kft with periods of broken deck
possible for brief times. A very isolated shower possible late
this afternoon/evening and would be southwest/west of GNV beyond
10 miles form the terminal. Some MVFR vsby is possible at VQQ in
light mist late tonight. Sfc winds will be east to southeast at
10-15 kt and gusty rest of the aftn, and becoming more southerly
tonight and Tuesday morning while decreasing.
-- End Changed Discussion --

&&

.MARINE...
Issued at 411 AM EDT Mon Apr 29 2024

High pressure centered off the Carolina coast will weaken and
shift eastward tonight and Tuesday as a weakening frontal boundary
enters the southeastern states. Breezy southeasterly winds and
elevated seas will continue through this evening before
prevailing winds shift to southerly by Tuesday morning. Seas of
3-5 feet are forecast through Tuesday night throughout our local
waters.

Isolated showers and thunderstorms may develop on Tuesday and
Wednesday as the dissipating frontal boundary moves over our area.
Another high pressure center will then build over coastal New
England late this week, resulting in onshore winds redeveloping
over our local waters. Seas of 2-4 feet are expected to prevail
throughout our local waters from Wednesday through the upcoming
weekend. A cold front is then expected to enter the southeastern
states by Saturday night and Sunday, possibly bringing a chance of
showers and thunderstorms to our region by late in the upcoming
weekend.

Rip Currents: Breezy onshore winds and elevated surf conditions
will create a high end moderate rip current risk at all area
beaches today, with breakers of 3-4 feet at the northeast FL
beaches and 2-3 feet at the southeast GA beaches. A moderate risk
will likely continue on Tuesday as breezy onshore winds develop
during the afternoon hours and breaker heights remain similar to
today. The risk may decrease towards midweek as surf heights
subside.

&&

.HYDROLOGY...
Issued at 411 AM EDT Mon Apr 29 2024

Water levels along lower portions of the Santa Fe River near the
Three Rivers Estates gauge will fall back to minor flooding later
this morning. Minor flooding is then expected to continue into
the upcoming weekend. Meanwhile, minor flooding will continue
along lower portions of the Santa Fe River near the gauge at
Hildreth through Tuesday, with water levels then expected to fall
below flood stage by Tuesday night. Otherwise, minor flooding will
continue along lower portions of the Suwannee River from the
gauge near Branford and points downstream today, with water levels
along most of the lower Suwannee River then falling below flood
stage before midweek.

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
AMG  61  87  64  89 /  10  40  30  10
SSI  66  81  66  84 /   0  10  20  10
JAX  62  87  65  87 /   0  20  20  20
SGJ  66  84  66  86 /   0  20  10  10
GNV  62  88  62  89 /  10  20  10  20
OCF  63  88  63  89 /  20  10  10  20
-- End Changed Discussion --

&&

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

$$