Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 081428
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
1028 AM EDT Wed Apr 8 2020

.UPDATE...

12Z sounding this morning showed unidirectional west southwesterly
flow through the column. There was speed shear evident with 0-6km
bulk shear around 55 knots. SPC has upgraded portions of southeast
Georgia to Slight Risk, and the rest of southeast Georgia and
portions of northeast Florida along the FL/GA border to Marginal
Risk. Scattered showers and embedded storms are expected to
develop in the early afternoon and move east across the area.
Another area of showers and storms is forecast to develop to the
west and northwest of the region late this afternoon, and then
move into southeast Georgia and towards the FL/GA border tonight
(between 00Z and 05Z). Some of these storms could become strong to
severe with the main threats being straight line winds and
marginally severe hail. Warm temperatures are expected with highs
in the mid to upper 80s.

&&

.PREV DISCUSSION [837 AM EDT]...

.NEAR TERM [Through Tonight]...

The upper ridge centered over the Yucatan flattens as zonal flow
develops aloft. Surface high pressure will remain south of the
area resulting in west-southwesterly flow over the area. Deep
layer west-southwesterly flow will advect warm, moist air into the
region increasing PWATS to 1.9" and highs into the mid to upper
80s. A weak disturbance aloft moves through the Gulf states today
into tonight. Scattered showers and thunderstorms will increase in
coverage across southeast Georgia beginning this afternoon and
spread southward toward the I-10 corridor of northeast Florida
into the evening hours. With 0-6 km bulk shear of 45-55 kt and
MUCAPE of 2000-25000 J/kg, an isolated strong to severe
thunderstorm cannot be ruled out. The highest potential will be
over southeast Georgia with locally damaging winds as the main
threat.


.SHORT TERM [Thursday Through Friday]...

Hot Thu with near record heat under breezy westerly flow as the
pressure gradient strengthens ahead of a cold front. As the front
slides across SE GA in the morning and approaches the I-10
corridor, expect a low chance of showers and potentially an
isolated t`storm given limited deep layer moisture and weakening
upper level forcing aloft but continued low level instability with
surface based CAPEs near 1500-2000 J/kg. Focused the best rain
chances near the I-10 corridor in the afternoon & evening, with
resultant rainfall tracking eastward as the surface front settles
south across NE FL Thu night. Cooler and stable northerly flow Thu
night trailing the surface front, but rain chances increase
toward sunrise Fri as PVA within the based of a long wave
mid/upper level trough deepening across the eastern CONUS streams
eastward across the Gulf Coast states. This mid/upper level lift
combined with unseasonably high moisture (PWAT 1-1.6" Fri) over
stable surface conditions will bring a cool, rainy day through the
day Fri with rainfall tapering off from north to south Fri
afternoon into Fri evening as yet another surface cold front
shifts across the local area as the upper level trough advances
downstream. Much cooler and dry Fri night as surface high pressure
builds north of the region, but conditions will become favorable
for shallow ground fog through sunrise Sat morning as skies clear
due to recent rainfall.

A temperature roller-coaster ride over this 48 hr period ranging
from record warmth on Thu with highs in the 90s, then trailing the
frontal passage Thu night highs will near 20 deg cooler Fri in the
low 70s under cloudy skies and cool rain. Minimum temperatures
will also plunge from the upper 60s to near 70 Thu morning,
cooling into the mid 50s to low 60s Fri morning, then falling
further into the mid 40s to low 50s inland by sunrise Sat.


.LONG TERM [Saturday Through Wednesday]...

A progressive pattern as a brief cooler and dry pattern Sat yields
to rain chances once again increasing Sat night into Sun morning
as a warm front lifts northward over the local area. There will be
a chance of isolated embedded, elevated thunderstorms within
lifting stratiform rainfall with warming temperatures Sunday as
the entire forecast area within the warm sector. Strong warm air
advection pattern returns Sun under breezy SW winds as highs once
again rise near 90 deg. Still some model timing differences with
the timing of a pre-frontal squall line crosses the local area
late Sun into Mon which could produce a few strong to severe
storms, then models do agree on the front stalling across the FL
peninsula late Mon into Tue as yet a stronger upper level trough
begins to deepen across the central CONUS. Temperatures will
moderate over the weekend to near daily highs potentially again on
Sun across NE FL. Generally cooling trend back toward near to just
below climo early next week with more cloudiness/convection.


.AVIATION...
[Through 12Z Thursday]

Scattered/broken stratus 700-1200ft this morning is forecast to
scatter out, with VFR cigs by 18Z. Scattered showers and isolated
storms are forecast to move across the area this afternoon and
evening, and have VCSH/VCTS at the TAF sites. West southwest winds
around 10 knots will prevail through the period.


.MARINE...

Long period northeast swells subside tonight. Surface high
pressure will remain south of the area through Thursday which will
continue west-southwest winds for the area waters. An isolated
thunderstorm will be possible this afternoon into evening for the
coastal waters. A cold front is forecast to move into the forecast
area by Thursday night and Friday with stronger northerly winds
expected Friday. The cold front will lift back north as a warm
front over the local area Saturday night.

Rip Currents: Moderate risk for NE FL and SE GA beaches today.


.FIRE WEATHER...

Warmer, unstable, and more moist southwest flow develops today
between high pressure south of the area and a front approaching
from the north. Breezy WSW winds will gust near 20 mph by early
afternoon with a weak east coast sea breeze pinned near the
Atlantic coast due to stronger SW flow. Scattered showers and
thunderstorms will increase in coverage across SE Georgia through
midday with less coverage of showers and storms southward toward
the I-10 corridor of NE Florida into the evening. Isolated shower
and thunderstorm potential again on Thursday as yet another front
slides south across the local area. Gusty WSW winds are expected
expected Thu as highs warm into the 90s with high dispersion.
Despite a low chance of rain, RHs will trend drier especially
north of the I-10 corridor where minimum values will range near
40%.


.HYDROLOGY...

A couple of gauges along the Atlantic coast have risen into Action
Stage during high tide over the past 12-24 hours. Water levels
continue to rise through the next couple of days with the peak of
astronomical tidal rise tonight (Apr 8-9) coinciding with offshore
flow with negligible `surge` impact. Total astronomical tide
inundation of 1-1.5 ft is possible per PETSS guidance. A Coastal
Flood Statement continues today to account for nuisance flooding
along the coast as water levels more uniformly rise into Action
Stage.

&&

.PRELIMINARY POINT TEMPS/POPS...

AMG  86  68  88  58  71 /  60  70  20  10  20
SSI  83  69  87  58  71 /  50  60  20  10  30
JAX  88  70  92  59  73 /  40  30  20  10  30
SGJ  86  69  88  60  71 /  30  10  20  20  40
GNV  86  69  88  60  72 /  20  10  20  20  40
OCF  86  69  86  64  75 /  10  10  20  20  50

&&

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



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