811
FXUS62 KJAX 301555
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1155 AM EDT Sun Jun 30 2024

...SLOW MOVING STORMS MAY PRODUCE LOCALLY HEAVY RAINFALL THIS
AFTERNOON AT INLAND LOCATIONS...
...STRONG TO SEVERE STORMS POSSIBLE ON MONDAY AFTERNOON FOR
LOCATIONS ALONG AND NORTH OF I-10...
...WIDESPREAD HEAVY DOWNPOURS AND LOCALIZED FLOODING POSSIBLE ON
MONDAY AFTERNOON AND EVENING 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

.UPDATE...
Issued at 1155 AM EDT Sun Jun 30 2024

Noon surface analysis depicts Atlantic high pressure (1021
millibars) extending its axis westward across north central FL.
Meanwhile, a weak surface trough was located over the southern
Appalachians and the Deep South, with a cold front extending from
the eastern Great Lakes through the Ohio and Tennessee Valleys and
the Ozarks pressing southeastward. Aloft..."Heat Wave" ridging
centered along the Red River Valley of northern Texas was
expanding into the southeastern states, with a potent shortwave
trough traversing southeastern portions of Ontario, Canada.
Otherwise, a Tropical Upper Tropospheric Trough (TUTT) axis
extends westward from the Bahamas across south FL. Latest GOES-
East derived Total Precipitable Water imagery indicates that a
seasonably moist atmosphere remains in place area-wide, with
values generally in the 1.9 - 2.1 inch range. Low-level troughing
over the Deep South was already developing scattered low-topped
convection late this morning for locations along the FL/GA border
to the west of the Suwannee River, with this activity pushing
slowly south-southeastward. A few showers are also developing east
of this activity along the I-10 corridor in the Suwannee Valley
and northeast FL. Otherwise, fair to partly cloudy skies prevailed
throughout our region at 16Z, with temperatures quickly climbing
toward the 90 degree mark at most locations, with dewpoints
generally in the low to mid 70s.

Ridging aloft to the west of our region and the TUTT axis to the
south of our area will create a deepening east-northeasterly flow
pattern aloft this afternoon. Deep moisture in place area-wide and
convective initiation temperatures in the low to mid 90s should
result in scattered showers and thunderstorms initially developing
ahead of the approaching surface trough and also along the inland
moving Gulf and Atlantic sea breezes early this afternoon.
Mesoscale boundaries should converge at inland locations west of
I-95 late this afternoon, with light northwesterly steering winds
resulting in slow storm motion and the potential for locally heavy
downpours through early this evening, mainly across southeast GA
and also along the U.S. Highway 301 corridor in northeast and
north central FL. Mesoscale boundary collisions may result in
storms pulsing at inland locations late this afternoon and early
this evening, with stronger activity being capable of producing
downburst winds of 40-50 mph and frequent lightning, along with
heavy downpours that will could result in localized flooding,
particularly at urban and normally flood prone locations. High
temperatures will generally rise to the 90-95 degree range before
convection and cloud cover increase across our area. We maintained
the Heat Advisory for portions of southeast GA, where values may
approach 108 degrees early this afternoon before convective
coverage increases. Maximum heat index values of 103-107 degrees
are forecast elsewhere.

Deep-layer east-northeasterly flow will focus convection closer to
the I-75 corridor in the Suwannee Valley and north central FL
early this evening, with forcing from the nearby surface trough
and mesoscale boundary collisions keeping slow moving convection
going past sunset across inland portions of southeast GA as well.
Localized flooding may be possible at urban and normally flood
prone locations in these areas early this evening. Convective
coverage should then wane towards midnight, with debris clouds
then thinning overnight. Lows overnight will range from the low to
mid 70s inland and the mid to upper 70s at coastal and urban
locations.

&&

.SHORT TERM...
(Monday through Tuesday night)
Issued at 330 AM EDT Sun Jun 30 2024

A cold front pressing down from out of the north is expected to
stall over Georgia by Tuesday with stronger convection developing
ahead of the frontal boundary with a potential for severe
thunderstorms forming on Monday over southeast Georgia and
adjacent Florida counties. Deep-layer moisture with PWAT values
rising to be about 2.25 to 2.75 inches ahead of the front will
result in storms capable of producing heavy rainfall with a
potential for localized flooding. High temperatures for the
beginning of the week will be in the 90s for most inland areas and
in the upper 80s along the coast and for areas behind the frontal
boundary. Overnight low temperatures will drop down into the mid
70s over inland areas and in the upper 70s along the coastline.
Heat advisory conditions may be possible on Monday and Tuesday as
heat index levels rise to 108 and above during peak daytime
heating.

&&

.LONG TERM...
(Wednesday through Saturday)
Issued at 330 AM EDT Sun Jun 30 2024

Convection will become relatively less widespread as the week
continues as drier air associated with the weakening front moves
to cover the forecast area with the prevailing flow becomes more
out of the north and northeast as high pressure shifts further
eastward. Daily high temperatures are expected to experience a
warming trend through the week with max temps rising into the
upper 90s going into the weekend. Potential for heat advisory
conditions will continue and become more likely by the end of the
period.

&&

.AVIATION...
(12Z TAFS)
Issued at 635 AM EDT Sun Jun 30 2024

A moist airmass will lead to diurnal showers and storms today,
mostly starting up around 18z and continuing into the evening
hours. Highest chances generally around GNV in the aftn. TEMPO
groups currently set for 18-23z time frame for sites with
convective developments forming in vicinity afterwards. Sfc winds
will be light and will allow the east coast sea breeze to develop
at SSI, CRG, and SGJ this afternoon and then become more light and
variable for sites overnight and into Monday morning.

&&

.MARINE...
Issued at 1155 AM EDT Sun Jun 30 2024

Atlantic high pressure stretching its axis westward across the
northeast Florida waters this afternoon will sink southward
tonight as a frontal boundary approaches our local waters from the
north. Offshore winds will prevail ahead of this approaching
frontal boundary, except near shore, where the Atlantic sea breeze
will push inland during this afternoon and again on Monday
afternoon. Seas of 2-4 feet will prevail both near shore and
offshore during the next several days.

Widely scattered showers and thunderstorms will be possible this
afternoon and evening, mainly over the near shore waters. The
frontal boundary will stall the Georgia waters on Tuesday, with
increasing chances for mainly afternoon and nighttime showers and
thunderstorms across our local waters. Prevailing winds will shift
to east and southeasterly beginning on Tuesday as high pressure
builds down the southeastern seaboard. High pressure will then
weaken as it shifts southward towards our local waters later this
week.

Rip Currents: Developing onshore winds this afternoon will combine
with a persistent long period easterly ocean swell to create a
lower end moderate rip current risk at all area beaches. This
moderate risk is expected to continue at area beaches on Monday.

&&

.FIRE WEATHER...
Issued at 1155 AM EDT Sun Jun 30 2024

Light westerly transport winds today will result in poor to fair
daytime dispersion values this afternoon. Breezy onshore surface
winds are forecast at coastal locations this afternoon as the
Atlantic sea breeze pushes inland. South-southwesterly transport
winds will become breezy on Monday for locations south of
Interstate 10, where good daytime dispersion values are forecast.
Lighter transport speeds and widespread afternoon showers and
thunderstorms will create generally poor to fair daytime
dispersion values on Monday for locations along and north of I-10.


&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  94  75  93  72 /  50  50  70  60
SSI  91  79  91  79 /  40  30  60  60
JAX  93  75  93  75 /  60  50  50  50
SGJ  90  76  91  77 /  40  30  40  40
GNV  93  73  93  75 /  60  70  50  30
OCF  92  73  92  75 /  60  60  50  30

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...Heat Advisory until 6 PM EDT this evening for GAZ136-151>154-165-
     166-264.

AM...None.
&&

$$