Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 221249
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
849 AM EDT Fri Oct 22 2021

.UPDATE...

The forecast remains on track. A cold front will slide south and
east into SE GA this afternoon with a few brief showers possibly
developing ahead of it from south GA into NE FL, but no storms
are expected. Skies will be partly cloudy with multi layer clouds
over the region and highs above seasonal values in the mid 80s for
most locations with light SW winds around 5-10 mph shifting to
the SE at the coast in the afternoon. The front will move through
the area late tonight with light and variable winds shifting to
the NW towards dawn with a few patchy areas of fog just ahead of
the front in parts of NE FL and north central FL near the Gulf
coast. Lows will cool into the mid/upper 50s over SE GA, low to
mid 60s over NE FL and the mid/upper 60s at the coast.


&&

.PREV DISCUSSION [749 AM EDT]...

.NEAR TERM [Today through Tonight]...Cold front over north Georgia
this morning will approach the area today as an upper trough digs
over the eastern U.S.  Isolated showers will be possible by
afternoon over se Ga/ne Fl but limited moisture will keep rain
chances low. The front will move across the area tonight with
shower activity dissipating this evening. Temperatures will be
warm today with highs reaching the mid 80s. Lows tonight will
range from the mid/upper 50s across se Ga to the low/mid 60s over
ne Fl.


.SHORT TERM...The weak shortwave trough that brought the front
to the area will move east of the area resulting in some height
rises, and especially as troughing over the Mid Atlc moves
offshore. A strong shortwave trough will move to the central and
northern Plains Sunday and dynamics remain well northwest the area
and still resulting in some gentle height rises for the area.
Thus, any cooling affect from the front will be short-lived. We`ll
see a weak sfc high to the north of the area Saturday that shifts
eastward and offshore of the Carolinas on Sunday, pushing well
east of the east coast on Monday. This will allow for the
transition of northerly sfc flow on Saturday to become onshore
Sunday and Monday. Gradual veering low to mid level flow and
moistening low levels should result in a slow increase in clouds
Sunday through Monday. A few showers may also develop Sunday
across the southeast counties and the marine zones due to weak low
level convergence. This slight chance of showers should continue
and slowly increase Sunday night, and expand to much of the area
on Monday, with a weak inverted sfc trough expected over offshore
waters. There is some instability available Sunday night through
Monday with MLCAPE values possibly in the 500-1000 J/kg range for
parts of the area. Given the weak low and mid level forcing and
lingering mid level dry air, will probably just have isolated
thunder mentioned over the coastal waters where the best
instability will be located. Max/min temps will trend slowly
warmer during this period due to the quick transition to onshore
flow. A weak front will approach from the north Monday night and
could support a bit better chance of thunder over the nrn zones
but moisture and dynamics remain pretty limited still.


.LONG TERM...Models suggest a weak frontal boundary will move
into the nrn zones Tuesday, with the ECMWF more amplified with the
mid level trough over the ern U.S. than the GFS. In any case, the
front should stall then push back northward near our forecast
area Tuesday night or Wed, ahead of a stronger cold front
approaching the region by the mid week. This system is progged to
reach our area Wed to Thu time frame, with the GFS and ECMWF
having some timing differences of about 6-12 hours, though appears
that both models have the front southeast/east of the area by Thu
evening. Fairly low instability / weak lapse rates but
compensating dynamic forcing and bulk shear >30 kt indicate a
potential for isolated strong to severe storms late Wed through
Thu morning. For now, POPs are shown to reach to only 40-50
percent Wed and Thu due to model discrepancies but will be refined
in the coming days as confidence increases on the timing and the
amount of forcing along the front. Temperatures will be near and
above normal Tue and Wed, then post- frontal temps a bit cooler
Thu and Fri.


.AVIATION...
[Through 12Z Saturday]

VFR conditions will prevail through the 12Z TAF period. Isolated
showers may be possible this afternoon and evening ahead of a weak
cold front but chances are still too low to include in TAFs. Light
Southwest winds at 5 to 10 knots expected today after 15Z and will
become east to southeast at kSSI, KSGJ and kCRG this afternoon. Mid
level clouds will pass over the region as the front approaches and
then disperse after 02Z with winds becoming light and variable towards
a light northwest flow as the front moves through the area to end
the period.


.MARINE... Surface ridge across the area this morning will shift
south as a cold front approaches the waters from the nw. The
front will move southeast across the area tonight. High pressure
will build to the north this weekend. A cold front will stall
across the area early next week with a stronger cold front moving
through Thursday.

Rip Currents: Low rip current risk today with offshore winds.
Moderate risk this weekend as winds become onshore.

&&

.PRELIMINARY POINT TEMPS/POPS...

AMG  83  55  80  52  83 /  10   0   0   0   0
SSI  84  64  81  64  81 /   0   0   0   0  10
JAX  86  64  83  60  83 /  20   0   0   0  10
SGJ  85  66  83  68  83 /  20   0   0  10  20
GNV  86  62  86  60  86 /  10   0   0   0  10
OCF  88  65  87  64  88 /  10   0  10   0  20

&&

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


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