690
FXUS62 KJAX 120818
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
418 AM EDT Wed Jun 12 2024

...THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL LATE THIS AFTERNOON
ALONG THE I-75 CORRIDOR...
...BREEZY ONSHORE WINDS THIS AFTERNOON ALONG THE ATLANTIC COAST...
...NEAR RECORD HEAT ON SATURDAY ACROSS SOUTHEAST GA...

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

.SYNOPSIS...
Issued at 418 AM EDT Wed Jun 12 2024

Early morning surface analysis depicts the center of Invest 90L
(1008 millibars) drifting northeastward across Tampa Bay.
Meanwhile, a stationary frontal boundary was draped from the
northern Gulf coast eastward along the Interstate 10 corridor.
Otherwise, weak high pressure (1018 millibars) was building
southward down the Appalachians mountains. Aloft...deep troughing
was slowly moving northeastward across New England, with westerly
flow in place locally downstream of a shortwave trough that was
progressing east-southeastward across the Ozarks and the lower
Mississippi Valley. Latest GOES-East derived Total Precipitable
Water imagery indicates that deep tropical moisture remains in
place for locations along and south of the stalled frontal
boundary, where PWAT values ranged from 1.8 - 2.0 inches, while a
much drier air mass remains in place across inland portions of
southeast GA, where PWAT values were generally in the 1.2 - 1.5
inch range. Pockets of low and mid level clouds were moving
northward from central FL into north central FL, with higher
altitude cloud cover in place across most of southeast GA.
Temperatures and dewpoints at 08Z were mostly in the 70s, except
at coastal locations, where temperatures remain around 80 degrees
at area beaches.

&&

.NEAR TERM...
(Today and Tonight)
Issued at 418 AM EDT Wed Jun 12 2024

Low stratus cloud cover and pockets of fog may expand somewhat
this morning, especially across north central FL. These lower
clouds should dissipate by the early to mid-morning hours.
Otherwise, low pressure will migrate northeastward along the
Interstate 4 corridor today, emerging off the FL Atlantic coast
near Daytona Beach this evening. Deep tropical moisture will
remain in place today for locations south of the Interstate 10
corridor, where convection should begin to develop later this
morning and this afternoon. Meanwhile, high pressure centered over
the Appalachians this morning will briefly wedge down the
southeastern seaboard today, creating a tightening local pressure
gradient across our region that will result in east-northeasterly
winds strengthening and becoming breezy from north to south along
the I-95 corridor and points eastward today.

These northeasterly winds will reinforce the already dry air mass
across southeast GA, and this flow will focus a more widespread
area of convection along the I-75 corridor late this afternoon and
into the evening hours as mesoscale boundaries collide within a
seasonably moist air mass along and south of the stalled frontal
boundary. Pulsing, slow moving convection may again result in
localized flooding later today, especially for urban locations
such as Gainesville and Ocala, where 1-3 inches of rainfall may
occur in a short period of time on a localized basis. Merging and
pulsing convection may result in a few briefly stronger storms
that will be capable of producing downburst winds of 40-50 mph and
frequent lightning strikes. Breezy onshore winds this afternoon
will keep coastal highs generally in the upper 80s, while inland
highs mostly reach the lower 90s, with a few mid 90s possible in
the Suwannee Valley.

Low level convergence will strengthen tonight as Invest 90L moves
slowly northeastward across the Gulf Stream waters adjacent to
northeast FL. These onshore winds may begin to advect showers and
possibly some lower topped convection onshore along the I-95
corridor during the overnight hours. Otherwise, evening convection
will wind down before midnight along the I-75 corridor, with
patches of lower stratus and fog possibly developing during the
predawn hours at locations that receive heavier downpours later
today. Lows tonight will generally fall to the 70-75 degree range
area-wide.

&&

.SHORT TERM...
(Thursday through Friday night)
Issued at 418 AM EDT Wed Jun 12 2024

The area of broad low pressure will have made its way off the FL
coast by early Thursday morning, remaining at a low chance of
any development due to a non favorable environment. Main focus for
this forecast period will be the increase chances of showers and
thunderstorms during the afternoon hours for both days for
locations south of the stalled frontal boundary in north central
Florida. Marginal risk for excessive rainfall by the WPC remains
for southern areas of Marion County on Thursday.

Daytime temperature highs will begin sit in the lower 90s for much
of the local area, with southern Marion County and coastal areas
dipping to the mid to upper 80s. Overnight lows will see
temperatures sit in the lower 70s across inland locations and in
the mid 70s along the coast.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 418 AM EDT Wed Jun 12 2024

With the frontal boundary finally making its way out of the local
area, in addition to the broad area of low pressure lifting off
towards the northeast, chances of showers and thunderstorms should
begin to lessen from the past couple of day. Enough moisture may
persist over the area to allow for afternoon showers and storms to
develop during the weekend and into the upcoming week.
Temperatures will look to rise to warmer than average levels
during the early portion of the weekend before more seasonal
levels become established as the Atlantic sea breeze will bring in
cooler air.

&&

.AVIATION...
(06Z TAFS)
Issued at 219 AM EDT Wed Jun 12 2024

Low MVFR ceilings of 1,000 - 1,500 feet are expected to develop
at GNV and VQQ after 08Z, with periods of IFR ceilings possible
around sunrise. MVFR ceilings of 2,000 - 3,000 feet are forecast
to develop after 12Z at SGJ, with periods of MVFR ceilings
possible at the Duval County terminals and SSI during the morning
hours. Confidence was too low to indicate anything other than
scattered ceilings at the Duval County terminals and SSI at this
time. Ceilings are expected to lift to VFR at the regional
terminals by 18Z. Showers and thunderstorms will develop during
the mid to late afternoon hours at the northeast FL terminals,
with activity increasing in coverage and intensity along the
Interstate 75 corridor during the late afternoon hours, and
confidence was high enough to include a PROB30 group at GNV after
19Z through 00Z, with IFR visibilities possible during heavier
downpours, along with brief wind gusts up to 30 knots. Showers
will begin to move onshore from the Atlantic waters towards the
end of this TAF period, possibly impacting the SSI and SGJ coastal
terminals as well as the Duval County terminals overnight. Light
southerly surface winds overnight at the northeast FL terminals
will shift to easterly after sunrise. Meanwhile, light easterly
winds overnight at SSI will shift to northeasterly towards
sunrise, with speeds increasing to around 15 knots and gusty after
15Z. Surface winds will shift to northeasterly at the rest of the
terminals after 17Z, with speeds increasing to 10-15 knots outside
of thunderstorm activity during the afternoon hours.

&&

.MARINE...
Issued at 418 AM EDT Wed Jun 12 2024

Weak low pressure moving slowly northeastward across Tampa Bay
early this morning will cross central Florida today, emerging over
the Atlantic waters near Daytona Beach by this evening.
Meanwhile, high pressure will briefly wedge down the southeastern
seaboard today, resulting in strengthening onshore winds later
this morning and this afternoon throughout our local waters. Seas
will build to 2-3 feet near shore and 3-5 feet offshore through
tonight. Showers and thunderstorms today will mainly be confined
to the waters from St. Augustine southward, with showers then
spreading northward overnight as low pressure crosses the Gulf
Stream waters adjacent to northeast Florida. Periods of showers
and thunderstorms will remain possible across the northeast
Florida waters on Thursday and Friday as a frontal boundary
remains stalled over our local waters.

This frontal boundary will briefly shift southward on Saturday
before a stronger high pressure center wedges down the
southeastern seaboard on Sunday. This weather pattern will result
in decreasing chances for showers and thunderstorms on Saturday,
followed by a surge in onshore winds on Sunday that will increase
chances for showers and thunderstorms throughout our local waters.
Seas of 2-4 feet will prevail both near shore and offshore from
Thursday through Saturday, with seas offshore then building to 3-5
feet by Saturday night and Sunday as onshore winds gradually
strengthen.

Rip Currents: Onshore winds will become breezy from north to south
today along our coast, creating a solid moderate rip current risk
by this afternoon at all area beaches. This moderate risk will
likely continue through Friday as a northeasterly ocean swell
develops in the wake of a departing low pressure center.

&&

.FIRE WEATHER...
Issued at 418 AM EDT Wed Jun 12 2024

East-northeasterly surface and transport winds will gradually
strengthen today, creating fair to good daytime dispersion values.
Locally heavy downpours are expected late this afternoon and early
this evening along the Interstate 75 corridor as thunderstorms
increase in coverage. Breezy northeasterly transport winds on
Thursday will create good to marginally high daytime dispersion
values across southeast GA and northern portions of the Suwannee
Valley, with cloud cover keeping values generally fair for
locations south of Interstate 10. Northeasterly surface and
transport winds will begin to weaken on Friday, but elevated
mixing heights will result in marginally high daytime dispersion
values across inland portions of southeast GA and northern
portions of the Suwannee Valley, with fair to good values expected
elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  91  70  93  69 /  20  10  20  10
SSI  87  75  87  75 /  20  30  40  20
JAX  91  72  90  72 /  30  40  60  20
SGJ  89  75  89  74 /  40  30  70  40
GNV  92  72  91  69 /  60  50  70  30
OCF  92  72  90  72 /  70  80  80  50

&&

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

$$