803
FXUS62 KJAX 231505
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1105 AM EDT Thu May 23 2024

...INCREASINGLY HOT WEATHER DURING THE MEMORIAL DAY WEEKEND...
...ISOLATED AFTERNOON AND EVENING THUNDERSTORMS POSSIBLE BEGINNING
ON FRIDAY...
...HEAT INDEX VALUES REACH THE 100-105 DEGREE RANGE THIS
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 1105 AM EDT Thu May 23 2024

Late morning surface analysis depicts high pressure (1019
millibars) centered near Bermuda and extending its axis
southwestward across our region. Meanwhile, weak surface troughing
extends to the south of this surface ridge across the southeastern
Bahamas and the Greater Antilles. Aloft...ridging centered over
the Bay of Campeche (southwestern Gulf of Mexico) was extending
its axis northeastward across our region, with cutoff troughing
located to the east of this ridge axis over the Bahamas and
central portions of the Caribbean Sea. Otherwise, troughing was
digging southeastward from the northern Rockies towards the High
Plains states, creating brisk zonal flow downstream of this
feature across the Southern Plains, Tennessee and Ohio Valleys.
Shortwave troughs embedded within this fast zonal flow pattern
were creating convection over the Ozarks, Tennessee Valley and
the Texas Hill Country, with high altitude debris cloudiness
emanating from these convective bursts progressing eastward across
the Deep South, with thinning cirrus moving overhead of our inland
counties late this morning. Plenty of sunshine and a relatively
dry and subsident air mass were allowing temperatures to climb to
the 80-85 degree range at most locations as of 15Z, with dewpoints
generally in the 65-70 range.

Flat ridging will continue to extend northeastward across our
region, with a shortwave trough expected to traverse the
Tennessee Valley and the southern Appalachians on Friday. Cirrus
cloudiness emanating from upstream convection will continue to
thin as it enters the more subsident air mass in place over our
area, with a relatively weak surface pressure pattern allowing for
the Gulf and Atlantic sea breezes to develop early this afternoon,
progressing inland and then colliding along the Interstate 75
corridor towards sunset today. There may be just enough low level
moisture in place to squeeze out an isolated shower or two along
the I-75 corridor towards sunset, but a relatively dry and
subsident air mass will prevent sustained updrafts and will negate
any chances for thunderstorms later today and this evening.
Otherwise, plenty of sunshine will boost highs to the lower 90s
inland, with breezy onshore winds in the wake of the Atlantic sea
breeze boundary keeping coastal highs generally in the mid 80
today. Dewpoints falling through the 60s this afternoon will keep
maximum heat index values below 100 degrees today.

The subsident air mass in place may foster some patchy fog
formation during the predawn hours along the I-75 corridor and
portions of inland southeast GA. Otherwise, thin cirrus will
continue to periodically progress overhead. Inland lows will fall
to the mid and upper 60s, ranging to the lower 70s at coastal
locations.

The shortwave trough progressing across the southeastern states on
Friday could provide a little more support for isolated afternoon
convection to develop near a collision of the Atlantic and Gulf
coast sea breezes along the U.S. Highway 301 corridor in southeast
GA, northeast and north central FL, mainly during the late
afternoon and early evening hours. The overall subsident nature of
our local air mass should keep convective activity brief in
duration and below strong or severe limits. Seasonably hot weather
will continue, with highs ticking up to the low and middle 90s
inland and the upper 80s at coastal locations. Dewpoints will
again fall into the 60s at inland locations on Friday afternoon,
resulting in maximum heat index values of around 100 degrees at
most locations.

&&

.AVIATION...
(12Z TAFS)
Issued at 642 AM EDT Thu May 23 2024

After brief MVFR/IFR fog at VQQ through 13Z this morning, VFR
will prevail for most of the period. High pressure will extend
from the northeast through tonight with light south to southeast
winds about 5 knots turning becoming easterly behind advancing
Atlantic seabreeze 5-8 knots inland and near 10 knots at coastal
sites. Afternoon diurnal cumulus clouds will form ahead of the
seabreeze with bases 4.0 kft to 6.0 kft away from the coast with
clearing behind the seabreeze save for thin cirrus clouds moving
in from the northwest. Light southeast winds will turn calm inland
overnight and turn southerly at the coast around 5 knots with
MVFR shallow fog at VQQ after 08Z.

&&

.MARINE...
Issued at 1105 AM EDT Thu May 23 2024

Weak high pressure will remain in place over our local waters
through the weekend, with afternoon sea breezes resulting in
breezy conditions during the mid to late afternoon hours for the
near shore waters and southerly evening wind surges expected
offshore. Speeds should mostly remain below Caution levels through
the period, with seas of 2-3 feet expected both near shore and
offshore. High pressure will then shift southeastward on Sunday
and Monday ahead of an approaching frontal boundary, resulting in
prevailing south-southwesterly winds. This frontal boundary will
stall across the northeast Florida waters on Tuesday and
Wednesday, where scattered thunderstorms will be possible.

Rip Currents: A lingering northeasterly ocean swell will combine
with breezy onshore winds during the afternoon hours today and
again on Friday to create a lower end moderate rip current risk at
all area beaches. This risk is expected to be low during the
Memorial Day weekend as the northeasterly ocean swell fades.

&&

.FIRE WEATHER...
Issued at 1105 AM EDT Thu May 23 2024

A mostly dry and increasingly hot weather pattern will continue
through the Memorial Day weekend, with only isolated thunderstorms
possible at inland locations during the afternoon and evening
hours from Friday through Monday. Minimum relative humidity values
will fall to around 35 percent at inland locations each afternoon
through the weekend. Despite generally light transport speeds
today, elevated mixing heights should create generally fair
daytime dispersion values at most locations. Transport winds will
shift to west-southwesterly on Friday and Saturday, with breezy
southeasterly surface winds developing along the I-95 corridor and
points eastward each afternoon following the passage of the
Atlantic sea breeze boundary. These winds will combine with
elevated mixing heights to create generally good daytime
dispersion values on Friday and Saturday.

&&

.HYDROLOGY...
Issued at 1105 AM EDT Thu May 23 2024

Water levels continue to gradually fall along upper portions of
the Satilla River, with minor flooding expected to continue into
Friday for locations around the gauge at Waycross. Water levels
downstream along the Satilla River near the gauge at Atkinson will
gradually rise, cresting this weekend and remaining in a minor
flood during the next several days. Water levels along lower
portions of the Santa Fe River near the Three Rivers Estates gauge
will continue to gradually rise as a flood wave progresses down
the Suwannee River, with levels remaining in a minor flood through
early next week and then possibly approaching a moderate flood
during mid to late portions of next week. This flood wave
traveling down lower portions of the Suwannee River should also
result in water levels rising above flood stage along lower
portions of the Santa Fe River near the gauge at Hildreth during
the early to middle portions of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  91  68  92  70 /   0   0  10  10
SSI  85  72  87  73 /   0   0  10  10
JAX  90  67  94  70 /   0   0  20  10
SGJ  86  70  88  71 /   0   0  10  10
GNV  92  67  94  68 /   0   0  10   0
OCF  93  66  94  68 /   0   0  10   0

&&

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

$$