870
FXUS62 KJAX 181815
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
215 PM EDT Sat May 18 2024

...New AVIATION...

.UPDATE...
Issued at 1045 AM EDT Sat May 18 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

The forecast remains on track with numerous showers and storms
developing throughout southeast GA into the late morning and early
afternoon. As this activity develops, northeast FL will continue to
see more sun and become more unstable, with the airmass more
favorable for northeast FL late morning and this afternoon for
scattered to numerous showers and storms to develop. Gusty winds,
heavy rainfall, and hail are the main threats given the
environmental bulk shear of 40-50 kt in place. The low level flow is
relatively unidirectional so the tornado threat is not high
(background SRH 0-3KM generally about 150 or less), but not out of
the question with some backing of the winds that an isolated tornado
develops later today, with the more favored area in about 3-6 hours
further south, closer to the southeast GA/northeast FL state line,
of the where the current convection is located. The threat of strong
or severe storms looks to decrease after about 6 pm as the airmass
gets worked over. Also, an isolated flooding threat in the near term
for inland southeast GA. Overall, little change in the forecast and
expect to see an uptick in showers and storms both intensity and
coverage near and southeast of a line from Jesup to Douglas over
southeast GA and into northeast FL as outflows and cells propagate
southeastward into more unstable airmass.

&&

.NEAR TERM...
Issued at 350 AM EDT Sat May 18 2024

Showers have nearly ended across our area from late night T`storms
that moved eastward across the SE GA and the FL/GA state line to
the coast and then offshore. Southerly flow, mostly light 5-10 mph
with a few higher breezes to 15-20 mph are keeping temperatures warm
in the mid 70s with very moist dewpoints around 70 and some low
stratus clouds may develop through sunrise over SE GA and inland NE FL.

Today, a compact mid level trough over Ozark Plataea/mid MS
valley will progress east through the TN river valley. A cold
front will move eastward across the FL panhandle with deep
moisture feeding into the area from the Gulf ahead of the front
and spur a wave of T`storms that will shift east northeast first
across interior SE GA from south GA and the FL panhandle late this
morning into midday, with greater uncertainty on T`storm
evolution into NE FL later this afternoon, but the The storm
prediction center has a Slight risk (category 2 out of 5) for
isolated to scattered severe T`storms for SE GA and much of NE FL
as many ingredients will be in place including strong deep
southwesterly shear values 50-60 knots 0-6km under divergent 250
mb jet streak crossing the deep south. Highs warming into the
upper 80s to lower 90s will aid strong instability well ahead of
the front and support a threat for gusty winds in excess of 60 mph
with more intense cells, hail, and even isolated tornadoes as
embedded supercell structures may contain stronger mesocyclones
that could promote a tornado or two. With deep moisture, efficient
rainfall rates will create localized heavy rainfall amounts that
could lead to minor flooding concerns (see hydrology section).

Otherwise, mostly cloudy skies will remain over SE GA with more
partly cloudy skies initially over NE FL and thus warmer highs
as mentioned. Southwest winds will pin the Atlantic seabreeze to
the immediate NE FL coast if not just offshore through much of
the afternoon.

Tonight will be moist and muggy with another round of showers and
T`storms as the cold front shifts through the area after midnight
Lows will be in the low 70s over NE FL and the upper 60s over SE
GA with light southwest winds under mostly cloudy skies.

&&

.SHORT TERM...
(Sunday through Monday night)
Issued at 350 AM EDT Sat May 18 2024

The aforementioned cool front will slow and stall across NE FL
through most of Sunday before a reinforcing frontal boundary slides
in from the north Sunday night. Meanwhile aloft, a trough will begin
its pivot maneuver across the Florida. Cold air aloft associated
with the trough and embedded shortwaves will crank up diurnal
instability with higher-end guidance around 1500-2000 j/kg CAPE.
This instability and modest westerly deep shear may result in
scattered strong and possibly marginally severe t`storms, with
particular focus along the stationary front lying south of I-10 in
NE FL. Given the unidirectional flow, the primary concern will be
strong outflow winds and small hail - tornadoes are very unlikely.
Showers and storms will fizzle through Sunday night as a cooler,
more stable airmass arrives. An additional concern will be training
storms along the stalled boundary, which may result in flood
concerns particularly at locations south of I-10.

Monday, high pressure will build in from the north, setting up a
northeasterly flow regime. Lingering moisture may result in enough
daytime instability to initiate isolated to widely scattered
showers, maybe an isolated storm, along the I-75 corridor as the
Gulf sea breeze attempts an inland push. Again, any daytime activity
will fade during the evening Monday.

Combo of showers/storms and cloud cover will limit temps the
mid/upper 80s Sunday with a readings trending 3-5 degrees cooler
into Monday as the reinforcing front arrives.

&&

.LONG TERM...
(Tuesday through Friday)
Issued at 350 AM EDT Sat May 18 2024

Though there could be a few lingering showers or even an isolated
storm across the southern zones Tuesday afternoon, the rest of period
should be rain-free as dry airmass tanks PWATs around an inch --
a typical amount for this time of year. Upper ridging will lean in
from the west next week, resulting in another increase in temps
with highs pushing back into the low 90s. Hot and humid conditions
will be the main concern as triple-digit heat index values make
another earlier-than-normal appearance.

&&

.AVIATION...
(18Z TAFS)
Issued at 200 PM EDT Sat May 18 2024

TAFs are generally on track with showers and storms affecting the
terminals today. Storms have moved through SSI and some lingering
showers will be possible there rest of the afternoon, with northeast
FL TAFs expected to see convection so have VCTS and TEMPO groups
into the evening hours. The primary times for TSRA is from now
through about 22z, with gusty winds around 30-40 kt and briefly
lower visibility. Still a risk of showers and isolated thunderstorms
tonight but for now carrying VCSH for the overnight hours. Sunday,
a risk of some showers and possibly a thunderstorm toward the end
of the TAF period.

Prevailing west to southwest winds 8-12 knots and becoming
lighter and southerly by midnight. Mainly westerly flow for
Sunday at about 10 kt.

&&

.MARINE...
Issued at 350 AM EDT Sat May 18 2024

A slow moving cold front will gradually push across the coastal
waters late tonight through Sunday, renewing chances for storms.
Winds will turn northerly as high pressure wedges against a low
pressure situated northeast of the waters early next week. High
pressure builds directly over the waters during the middle part of
next week.

Rip Currents: Low Risk of rip currents at all area beaches today
and Sunday.

&&

.HYDROLOGY...
Issued at 350 AM EDT Sat May 18 2024

While some locally heavy rainfall occurred along the FL/GA state
line overnight, much of NE FL recovered very little rain Friday.
With the approach of the cold and expected T`storms later today
and again tonight, expecting widespread 1-2 inch totals over SE GA
and inland NE FL with locally heavier amounts of 3 inches in
isolated locations where more intense storms travel or train over
with overall less amounts towards the NE FL coast. Minor flooding
is possible in low lying and urban areas and flood prone roads.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  68  85  65  83 /  60  60  20  20
SSI  71  85  67  79 /  70  70  30  30
JAX  71  88  67  82 /  70  70  30  40
SGJ  71  88  69  81 /  70  70  40  40
GNV  70  86  66  86 /  60  70  20  50
OCF  72  86  69  86 /  60  70  20  50

&&

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

$$