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000
FXUS62 KJAX 060804
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
404 AM EDT Thu May 6 2021


.NEAR TERM [Through Tonight]...

Latest satellite imagery show high clouds moving eastward on the
zonal flow aloft along with areas of mid and lower cloud as well.
At the surface, observations and webcams have indicated some
shallow fog generally along and west of the I-75 corridor. Fog may
shift further east toward Gainesville and Ocala over the next few
hours but is generally expected to be patchy in nature and lift
quickly at sunrise.

Radar returns have been few and far between early this morning but
that is expected to change as dawn approaches. A cold front,
currently entering the northern GA zones, will push further south
toward the state line through late morning hours. Showers are
expected to blossom this morning along the front, with the best
chances across the Suwannee Valley and along the FL/GA border as
frontal convergence increases. Shower coverage and t-storm chances
will increase during the early afternoon, generally along and south
of Interstate 10, as an upstream shortwave trough axis begins a
pivot maneuver across the Southeast. As this occurs, instability
will increase further with steepening lapse rates. Forecast
soundings south of the I-10 corridor indicate peak CAPE values
ranging from 1500-2000 joules and bulk shear around 30-40 kts
between 3-6 PM this afternoon. These thermodynamic parameters may
support strong to marginally severe storms through the afternoon,
mainly south of a line from Gainesville to St Augustine. Primary
threats will be strong downbursts from collapsing storms and small
hail. Though a few localized areas could pick up 1-1.5" of rain
with training t-storms, the flood threat will be low due to the
recent dry weather. Showers and isolated embedded t-storms may
linger across north-central FL into the early evening as the cold
front begins to exit to the south.

A drier, cooler airmass will filter in behind the front bringing a
much welcomed relief to the area after several days of record
warmth. Afternoon highs today will vary considerably with the
influence of the frontal zone and cloudy skies. Generally, expect
afternoon temps in the lower 80s across SE GA, mid 80s across NE FL
and upper 80s to near 90 across the far southern zones. With the
cooler air filtering into the region, lows tonight are forecast
to dip into the mid 50s across SE GA and upper 50s/low 60s across
the NE FL zones.


.SHORT TERM [Friday Through Saturday]...

Sfc high pressure will build in from the northwest with very dry
conditions and deep northwesterly flow. The pressure gradient
over the region will support breezy northwest winds around 15 mph
with gusts around 30 mph mainly from I-10 northward. Despite
sunny skies, temps will be slightly below normal in the wake of
the cold front.

We should still see some breezy northwest winds Friday evening
given the high will still be over MS and AL. GFS and NAM both bring
the sfc high to srn GA by sunrise on Saturday so very light
northwest to calm winds should be common by that time. Will go
with blend of MOS and NBM forecast lows from about 45 to 50
inland, and lower to mid 50s along the coastal areas.

Saturday, sfc high pressure will be centered over the area and
expect much warmer temps by the afternoon after the cool morning
temps. Should see both Gulf and Atlantic sea breezes in the aftn
but much too dry for precip. Near normal max temps expected. Sat
night, sfc high pressure will move offshore of the east coast and
low level flow turns southerly. Not as cool but lows in the 50s to
around 60 expected.


.LONG TERM [Sunday Through Thursday]...

Sunday, a high pressure ridge will be located across central and
south FL with low level southerly flow, with highs above normal.
Should see a slight increase in moisture but no precip expected
over our forecast area.

Sunday night into Monday, a cold front extending southwest from a
surface low over the Ohio Valley to southeast TX will move east
to southeast. Southern stream shortwave, in generally zonal flow
aloft, may end up producing a cluster of showers and storms ahead
of the cold front eastward toward or over the area on Monday, with
a risk of isolated strong storms possible over southeast GA.

The frontal boundary may become nearly stationary near the FL/GA
line or over northeast FL Tuesday as flow aloft remains fairly
zonal. ECWMF, and to some extent the GFS, develops a frontal wave of low
pressure west of the area Tuesday night then pushes it east
toward our area on Wednesday. However, ECMWF and GFS are inconsistent Wed-
Thu depicting these features, with ECWMF moving the front north
of the area Wed night and the GFS showing the front staying
over the forecast area around north central FL. Given the disparity
in the guidance, confidence is low on precip and temps at the end
of the period. For now, we carry low POPs Wed and Thu before the
front passes through. Temps will be near to above normal.


&&

.AVIATION...
[Through 06Z Friday]

A lull in showers is expected through around daybreak along with
MVFR ceilings at most TAF sites. GNV is the only terminal with at
least a slight chance at IFR ceilings and temporary vsby
restrictions due shallow ground fog this morning. Showers should
begin to develop and expand in coverage after sunrise as a cold
front across southeastern GA slides southward. Most of the shower
activity should favor northeast FL throughout the period. Current
guidance, indicates a favorable window for thunderstorms between
17z-22z, so introduced a TEMPO for most TAF sites with the
exception of SSI with it being on the stable (north) side of the
front. MVFR ceilings are expected through most of the day with
local vsby restrictions with convection. Skies will begin to
scatter out this evening as the front proceeds south of the area.

&&

.MARINE...

A front will continue to slide across coastal waters today and exit
to the south late this evening. A few of waves of shower and storms
are expected ahead of and along the front as progresses through the
area waters. A few storms may be strong and produce locally gusty
winds. High pressure will build from the northwest behind the front
on Friday. Northwest winds between 15-20 knot with gusts, possibly
frequent, up to 30 knots are expected Friday as cooler air is
advected over the recently warmed shelf waters amid a tightened
gradient. A Small Craft Advisory may need to be considered for
Friday in a subsequent forecast. High pressure will shift overhead
Saturday and then east on Sunday. This will weaken and veer winds
onshore Saturday then southerly on Sunday. Another period of
unsettled weather is expected next week as couple of weather
disturbance and frontal system approaches from the region.

Rip Currents: An offshore wind ahead of the cold front and
generally low surf will limit rip current risk at area beaches
today and Friday.

&&

.FIRE WEATHER...

Locally breezy westerly winds today ahead of a cold front with
areas of high dispersion over southeast GA. Min RH will be above
critical values today but post-frontal dry air northwest of
Waycross may drive RH to 30-35 percent.

On Friday, much drier and not as warm but breezy northwest sfc and
transport winds will result in high dispersion above 75. Min RH
values were adjusted slightly down from prior forecast to near
25-28 percent. If some decent rainfall occurs over northeast FL
today, this will help mitigate an elevated fire danger. Elevated
fuel moisture values in southeast GA Friday will keep fire
danger on the low side.

&&


.PRELIMINARY POINT TEMPS/POPS...

AMG  81  55  77  48  81 /  10   0   0   0   0
SSI  79  61  80  56  77 /  50  10   0   0   0
JAX  81  60  82  49  80 /  60  10   0   0   0
SGJ  81  63  82  58  77 /  60  20   0   0   0
GNV  83  58  82  49  83 /  70  20   0   0   0
OCF  88  62  84  51  85 /  60  20   0   0   0

&&

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