990
FXUS62 KJAX 151309
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
909 AM EDT Wed May 15 2024

...New UPDATE...

.UPDATE...
Issued at 822 AM EDT Wed May 15 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

Surface front is currently upstream of the region extending from
central Georgia through the FL Panhandle into the central Gulf of
Mexico. This feature will slowly migrate to the southeast through
the day. Pooling of moisture is evident on satellite and surface
observations with dewpoints in the lower 70s south of the FL/GA
border with low layer streamline analysis showing deep moisture
tap from the GOM with southwesterly flow. Precipitable water
values are now above 1.6 inches south of I-10 where the main
focus for convection will be this morning through mid afternoon
where  Convection over GOM will advect into Apalachee Bay and the
Nature Coast pressing into our region while blossoming in areal
coverage and strength as the morning progresses. At the same time
the upper trof will continue to track across the SE U.S. which has
brought 500 mb temps at -9 to -10 C. With cool mid level temps,
hail (perhaps large) and strong gusty and isolated damaging
thunderstorm wind gusts (40-60 mph) will be main threats with any
of the stronger updrafts tapping into cooler air aloft. An
isolated tornado cannot be ruled out mainly south of SR16 as
well, though this potential looks low at this time with a smaller
time window potential with more speed shear with height as
opposed to directional shear this late morning through mid
afternoon. Tornado watch #243 continues for Flagler, Putnam, St.
Johns and Marion Counties though 11 am.

The line of showers and storms is expected to slowly sink south
through the mid afternoon with northwesterly steering winds
working into the region as surface cold front moves into coastal
Georgia and Suwannee Valley. Current forecast, messaging on
NWSChat 2.0 and social media channels look on track.

&&

.NEAR TERM...
Issued at 201 AM EDT Wed May 15 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

Shortwave energy crosses southern and central parts of the area
tonight, and combined with plentiful moisture and elevated
instability will develop showers and thunderstorms overnight,
especially from about I-10 southward. In addition, a cold front is
approaching western GA as of the 03Z WPC surface analysis, which
will continue to shift southeastward throughout the night and
today. Effective/0-6km shear is definitely sufficient, but the
more significant element is the amount of available energy,
especially aloft, where forecast soundings indicate near or about
2000 J/kg of MUCAPE or higher, with noticeable amounts within the
hail growth zone. Therefore, expecting hail to be the primary
threat with any stronger updrafts, though shear and kinematics
certainly would warrant strong wind potential of 40-60mph. An
isolated tornado cannot be ruled out as well, though this
potential looks marginal.

Overnight convection will be persistent into the late morning to
early afternoon hours while slowly drifting south with the
approaching front and associated dynamics aloft with the parent
upper trough. Expecting a similar threat to play out for southern
counties in northeast FL for the late morning to afternoon period,
as vertical profiles will remain similar (high CAPE and sufficient
shear). It is certainly possible for a couple of showers and
isolated thunderstorms to pop up immediately ahead of the
approaching front though lagging behind overnight activity as the
front progresses southeastward (as far north as north of I-10),
in which some high res solutions are suggesting. Though the
severe threat should drop off quite a bit from south of north
throughout the afternoon as a lot of drier air works its way in
aloft. Southwest to westerly winds will also be quite breezy
today, though below wind advisory criteria (10-20 mph and gusts
in the upper 20s to 30s). Temps will be not as traditional today
due to the frontal boundary and morning convection - generally in
the mid to upper 80s south of I-10, with some areas approaching 90
possible over a stretch of southeast GA.

The front should settle sufficiently south of the region by
tonight as some drier air near the surface and especially aloft
fills in. Overall decreasing clouds and lows in the 60s inland,
and near 70 near the St. Johns River and coast.

&&

.SHORT TERM...
(Thursday through Friday night)
Issued at 201 AM EDT Wed May 15 2024

Thursday...Dry airmass in place between weather systems will
continue mainly dry conditions under mostly sunny skies with above
normal temps reaching into the upper 80s/lower 90s over inland
areas with West-Northwest winds at 10-15 mph and East Coast sea
breeze remains pinned closer to the Atlantic Coast.

Thursday Night...High clouds slowly increase ahead of next weather
system with light SW winds at the surface. Low temps in the 60s
inland and lower 70s along the Atlantic Coast. Dry conditions will
continue.

Friday...Moisture levels will continue to slowly increase ahead of
the weekend weather system in the low level SW steering flow and
this may be just enough to trigger afternoon/evening shower/storm
activity along the sea breezes as they move further inland and
meet along the US 301 corridor later in the day. Temps continue
well above normal in the upper 80s SE GA and lower 90s NE FL with
slightly lower values along the Atlantic Coastal areas.

Friday Night...Still some significant model diffs as the faster
ECMWF bring in pre-frontal showers/storms in this period while the
latest GFS/NAM keeping activity to the NW of the region with
mostly dry and humid conditions, so for now have been keeping with
model blends which keep scattered showers/isolated storms going
through the night with above normal low temps in the lower/middle
70s.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 201 AM EDT Wed May 15 2024

Saturday...Next frontal boundary pushes into the region with a
return to heavy rainfall and isolated strong to severe storm
potential area-wide and rainfall chances already in the 60-80%
range. Above normal temps will continue ahead of the frontal
boundary with upper 80s SE GA and still into the lower 90s for NE
FL with Heat Indices still close to 100F across NE FL.

Sunday/Monday/Tuesday...Models coming into better agreement that
in the wake of departing storm system a drier airmass will push
into the region on Northwest flow with limited rainfall chances
and temps still slightly above normal but not as hot with Max
temps in the 85-90 range and lows 65-70. Some limited moisture
return by Monday and Tuesday may lead to widely scattered
afternoon/evening showers and storms along sea breeze boundaries
but overall below normal rainfall chances are expected.

&&

.AVIATION...
(12Z TAFS)
Issued at 720 AM EDT Wed May 15 2024

Patchy fog will dissipate over the next hour or two at KVQQ and
KGNV. An area of convection over the NE Gulf of Mexico is starting
to fill in and enhance the past hour and will eventually push
into the Nature Coast the next hour. The convection will continue
to strengthen and increase in areal coverage while pressing into
area terminals, particularly south of I-10 across NE FL and north
central FL. With stronger storms that occur brief drops in cigs
and vsbys may occur with heavy downpours in addition to brief
gusty tstm winds and potential for hail between 15z and 20z. GNV
and SGJ are will have the highest chances for TSRA as well as
strong to severe TSRA, which will last into the late morning to
afternoon hours. Some storms could be capable of gusts of 35-55
knots. The heavy rainfall and lower ceilings will also cause
periods of MVFR and isolated IFR, as indicated in TEMPO groups.
TSRA and especially strong/severe TSRA threat subsides from north
to south at terminals this afternoon and into the evening, with
only some isolated SHRA lingering before sunset. VFR is expected
to return between 22z and 00z. During the nocturnal hours VFR
conditions are anticipated.

&&

.MARINE...
Issued at 201 AM EDT Wed May 15 2024

Widespread showers and the potential for strong to severe storms
are expected over our local waters through the morning hours.
Stronger storms may produce damaging wind gusts, hail and even
waterspouts. Storms and showers will shift southeastward late
Wednesday morning as a cold frontal boundary shifts southward
through the waters.Conditions will improve from north to south
Wednesday afternoon and evening, with breezy westerly winds
expected outside of thunderstorms that will gradually subside by
Thursday afternoon as weak high pressure moves over the
southeastern states. Winds will turn southerly on Friday ahead of
the next frontal boundary that will impact our area this weekend.
Showers and thunderstorms will likely impact our local waters from
Saturday afternoon through Sunday morning, with a few strong
storms possible. Winds will then shift to northwesterly by Sunday
afternoon and night as this front pushes offshore.

Rip Currents: Moderate rip current risk continues today due to
unsettled weather, dropping to low Thursday with generally
weakening offshore flow.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  87  66  88  66 /  10   0   0   0
SSI  88  70  86  72 /  30   0   0   0
JAX  88  68  91  68 /  50  10   0   0
SGJ  87  69  90  69 /  70   0   0   0
GNV  85  66  90  66 /  80   0   0   0
OCF  84  69  90  65 /  90   0   0   0

&&

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

$$