660
FXUS62 KJAX 151755
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
155 PM EDT Mon Jul 15 2024

...New AVIATION...

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

.AVIATION...
(18Z TAFS)
Issued at 156 PM EDT Mon Jul 15 2024

Strong thunderstorms will likely impact the GNV terminal through
around 20Z, with the potential for brief wind gusts in excess of
30 knots and IFR conditions during heavier downpours. Activity
should then focus near or over the rest of the northeast FL
terminals and SSI, where TEMPO groups were placed at each TAF
site, generally between 19Z and 00Z. Periods of IFR conditions and
gusty winds are expected at the Duval County terminals, SSI, and
SGJ as this slow moving activity persists through around sunset
before diminishing in coverage early this evening. Periods of
MVFR visibilities are likely overnight at VQQ. Outside of
thunderstorm activity, southeasterly surface winds will remain
sustained at 10-15 knots at the SSI and SGJ coastal terminals
through around 23Z. Surface winds will then shift to southerly
after convection ends around or shortly after sunset, with surface
speeds diminishing to around 5 knots by 06Z at the coastal
terminals and less than 5 knots inland. Surface winds will then
shift to southwesterly shortly after sunrise, with sustained
speeds increasing to 5-10 knots by 15Z Tuesday.

&&

.UPDATE...
Issued at 1215 PM EDT Mon Jul 15 2024

Early afternoon surface analysis depicts the axis of Atlantic high
pressure (1024 millibars) extending its axis across the FL
peninsula and into the southeastern Gulf of Mexico.
Aloft...ridging was centered off FL`s Atlantic coast, or just
north of the northwestern Bahamas, while troughing was progressing
eastward across the eastern Great Lakes, Ohio and Tennessee
Valleys. Meanwhile, a leftover Mesoscale Convective Vortex (MCV)
from widespread thunderstorm activity that occurred last evening
along the Interstate 4 corridor in central FL was spinning over
the Nature Coast, and this feature was activating isolated
convection along the Gulf coast sea breeze along the FL Big Bend
and Nature Coasts, with a few showers otherwise developing in the
hot and humid air mass along the I-75 corridor in the Suwannee
Valley as well as the U.S. Highway 84 corridor across inland
southeast GA. Latest GOES-East derived Total Precipitable Water
imagery indicates that deep moisture remains in place throughout
our region, with PWATS in the 1.9 - 2.2 inch range. Multi-
layered cloudiness was prevalent closer to the MCV feature across
north central FL, with a healthy cumulus field otherwise
developing across our area. Temperatures at the noon hour were
skyrocketing to the upper 80s and lower 90s, with dewpoints in the
mid to upper 70s creating heat index values that generally ranged
from the upper 90s to around Heat Advisory criteria (108 degrees).

The presence of deep tropical moisture and the aforementioned MCV
feature will trigger scattered to numerous thunderstorms this
afternoon, with activity initially focused along the inland moving
Gulf Coast sea breeze along the I-75 corridor in the Suwannee
Valley and north central FL, with isolated activity developing
elsewhere along differential heating boundaries as well as the
Atlantic sea breeze boundary. Southwesterly low level flow will
tend to slow the inland progress of the Atlantic sea breeze this
afternoon, setting up a collision of outflow boundaries and
eventually the Atlantic and Gulf coast sea breezes for locations
between U.S. Highway 301 and Interstate 95 during the late
afternoon and early evening hours. Storms may pulse as mesoscale
boundaries collide, with stronger activity being capable of
producing downburst winds of 40-50 mph, frequent lightning
strikes, and locally heavy downpours. Steering flow will remain
light, resulting in slow moving storms that could result in
localized flooding, especially if activity moves slowly or
back-builds over urban or normally flood prone locations. Outflow
boundaries will also migrate northward across inland southeast GA
this afternoon, where convection may linger past sunset tonight.

High temperatures this afternoon will soar to the mid and upper
90s, except for north central FL, where thicker multi-layered
cloudiness should keep highs in the lower 90s. Peak Heat Index
values should reach Heat Advisory criteria of 108-112 degrees
behind the inland moving Atlantic sea breeze this afternoon for
the coastal zones in both northeast FL and southeast GA, while
peak values elsewhere mostly reach the 103-107 degree range.
Debris cloudiness from this afternoon and evening`s convection
will gradually thin out overnight, with lows mostly falling to the
mid 70s inland, ranging to around 80 at coastal locations.

&&

.MARINE...
Issued at 1215 PM EDT Mon Jul 15 2024

The axis of Atlantic high pressure will stretch across the Florida
peninsula through midweek, keeping a prevailing southerly wind
flow in place across our local waters. A few strong thunderstorms
will be possible late this afternoon and early this evening,
mainly over the near shore waters, with stronger storms being
capable of producing briefly strong wind gusts, heavy downpours,
and frequent lightning strikes. Outside of thunderstorm activity,
southerly winds will surge this evening before shifting to
southwesterly and weakening after midnight. A similar weather
pattern will prevail on Tuesday, followed by Atlantic high
pressure sinking southward later this week as a frontal boundary
enters the southeastern states. Seas of 3-5 feet will prevail both
near shore and offshore through Tuesday night. Mainly afternoon
and evening thunderstorms will increase in coverage throughout our
local waters later this week as this boundary stalls to the
northwest of our local waters. Seas will diminish to 2-4 feet
throughout our local waters towards midweek.

Rip Currents: A persistent east-southeasterly ocean swell will
combine with breezy onshore winds during the afternoon hours to
create a moderate rip current risk at all area beaches through at
least midweek.

&&

.FIRE WEATHER...
Issued at 1215 PM EDT Mon Jul 15 2024

Southwesterly transport winds this morning will tend to shift to a
more southerly direction by late afternoon, outside of developing
thunderstorm activity. Stronger thunderstorms will tend to focus
along the Interstate 95 corridor during the late afternoon hours,
with stronger storms later this afternoon being capable of
producing briefly strong wind gusts, frequent lightning strikes,
and slow moving, heavy downpours. Lighter transport winds and
more cloud cover over north central FL will keep daytime
dispersion values generally poor today, with fair to good values
expected elsewhere away from coastal locations. Light
southwesterly transport winds will continue on Tuesday and
Wednesday, with scattered to numerous afternoon and evening
thunderstorms expected across our region.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  76  95  75  95 /  40  60  20  70
SSI  80  92  79  93 /  50  50  40  60
JAX  75  95  76  96 /  70  70  30  70
SGJ  77  94  77  94 /  40  70  30  60
GNV  74  94  73  93 /  60  80  20  80
OCF  74  95  75  93 /  40  90  30  80

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Heat Advisory until 6 PM EDT this evening for FLZ124-125-133-138.

GA...Heat Advisory until 6 PM EDT this evening for GAZ154-166.

AM...None.
&&

$$