Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 220708
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
308 AM EDT Sun Oct 22 2017

...STRONG COLD FRONT MOVES THROUGH ENTIRE REGION LATE MONDAY/EARLY
TUESDAY...

.NEAR TERM /TODAY-TONIGHT/...

High Pressure NE of the region will slowly pull further offshore
into the Wrn Atlc and SE steering flow will continue to veer to
the South and atmospheric moisture will continue to increase and
lift remnants of old frontal boundary into NE FL/SE GA this
afternoon and evening and expect numerous showers and embedded
thunderstorms with some locally heavy rainfall possible mainly
across NE FL coastal areas this afternoon. Temps will continue
above normal with highs into the lower/middle 80s despite the
Mostly Cloudy skies by this afternoon. Breezy onshore flow will
linger at the coast as E/SE winds increase to 15-20G25 mph.
Tonight the surge of moisture with old frontal boundary will push
northward into SE GA with only isolated showers across NE FL while
scattered showers and embedded storms will continue to be possible
across the coastal waters and portions of SE GA especially towards
morning. The mild southerly flow will keep overnight temps well
above normal in the lower to middle 70s. Widespread rainfall
amounts of 0.25-0.50" expected through tonight with isolated
higher totals in any thunderstorm activity that develops.

.SHORT TERM /MONDAY THROUGH TUESDAY/...

.Monday and Monday night...Initially Monday morning, the best
moisture will be along and west of I-75 across north Florida and
also over far west interior portion of SE Georgia where
precipitable water values range 1.60 to 1.75" with drier PWATS
along the I-95 corridor 1.30 to 1.50". Mean moisture will markedly
increase through the day Monday with PWATS near 2" as the low
levels veer out of the southwest Monday afternoon and early
evening ahead of a vigorous deep layer trough and pre-frontal
trough/band of showers/storms. Discrete storms that manage to get
going in the warm air mass may be briefly strong to severe given
that there will be a 40 to 45 knot low level jet but instability
overall will be lacking given extensive cloud cover and precip
inhibiting boundary layer destabilization while minimizing
convective potential. The best instability will reside south of
I-10 to north central FL where CAPES will be between 750 to 1250
J/kg between 18z and 21z Monday which will have the best chance
for embedded thunderstorms. Numerous showers with isolated thunder
will linger into a portion of Monday night as the mid level trof
axis extends from just offshore of SE GA to the Big Bend region as
the cold front resides from coastal Georgia, just west of JAX to
Ocala around midnight.

.Tuesday and Tuesday night...Showers will end sharply from
northwest to southeast Tuesday morning as the dry slot moves in
behind the front. Much cooler and drier air moves in with below
normal temps expected most areas especially Tuesday night. Min
temps are forecast to dip into the 40s across the Suwannee Valley
into inland Se Ga with lows in the lower to mid 50s elsewhere.

.LONG TERM (Wednesday-Saturday)...

High pressure builds in from the Lone Star state and Gulf Coast
which ushers in fall-like conditions across much of the region.
Low temps in the 40s across much of the inland areas Thursday
morning with lower to mid 50s near the coast. Highs will struggle
to reach the 70 degree mark across the region on Wednesday and
will still be held to much below normal Thursday. Modest return
flow develops beginning late Thursday night into Friday as high
pressure pushes offshore but temps still held to slightly below
normal. Rain chances begin to increase next weekend with the
approach of the next vigorous trough.


&&

.AVIATION...
Increasing Rain Chances today will provide for better chances of
MVFR CIGS in scattered shower activity and tstm chances increase
at NE FL TAF sites this afternoon enough to include VCTS from
16z-00z, then rain chances decrease during the evening with just
lingering VCSH and still mainly VFR with some MVFR CIGS still
possible.

&&

.MARINE...
SCEC conds will continue today and tonight with E/SE winds at
15-20 knots and seas 4-6 ft. Winds continue to veer to the S/SW on
Monday ahead of the front but still expected to remain just below
advisory levels with the frontal passage and become NW Tue/Wed/Thu
but still expected to peak out in the 15-20 kt range for now.

Rip Currents: With continued onshore flow and elevated surf/swells
will continue High Risk one more day, then Moderate on Monday.

&&

.HYDROLOGY...
Minor Flooding will continue on the St Johns River Basin today
with some possible Moderate Flooding during high tide across
Putnam County so will keep Flood Advisories/Warnings in place for
now. Flooding should subside even further early this week as flow
becomes offshore behind frontal passage and allows for St Johns
River Basin to lower below flooding levels.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  85  71  79  60 /  30  40  80  50
SSI  80  74  80  67 /  50  50  70  60
JAX  84  72  81  65 /  60  40  60  50
SGJ  83  73  82  67 /  70  50  60  50
GNV  86  71  81  64 /  70  40  70  50
OCF  86  71  83  66 /  60  30  70  50

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through late tonight for Coastal Duval-
     Coastal Nassau-Flagler-St. Johns.

     Coastal Flood Advisory until 6 AM EDT Monday for Clay-Coastal
     Duval-Flagler-Inland Duval-St. Johns.

     Coastal Flood Warning until 6 AM EDT Monday for Putnam.

GA...High Rip Current Risk through late tonight for Coastal Camden-
     Coastal Glynn.

AM...None.
&&

$$

Hess/Cordero



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