Area Forecast Discussion
Issued by NWS Jacksonville, FL

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868
FXUS62 KJAX 190851
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
351 AM EST Sun Nov 19 2017

.CURRENTLY...Broad mid to upper level trough is located from the
eastern Great Lakes to the east Gulf coast with accompanying cold
front located from 983 mb low over NY To central NC to the FL
panhandle. Cold front is moving quickly east-southeast and is
associated with a line of showers...with some trailing light rain
within about 20-30 mi behind it.

.NEAR TERM.../EARLY TODAY THROUGH TONIGHT/...
The cold front will be accompanied multilayered clouds and broken
line of showers this morning some of which may produce gusty winds
of about 30-40 mph. Placement of the front around 7AM is roughly
along a line from St Mary`s GA to Cross City FL. Based on latest
consensus forecast and radar echoes have bumped up POPs a bit for
the morning hours but the front will be moving quickly and rain
duration will be short with QPF remaining at or below a tenth of an
inch. The fast moving front will be south of the area by 1 PM.
Moderate cold advection, breezy northwest flow at times, and some
lingering clouds will result in high temps in the 60s over southeast
GA, and upper 60s to lower 70s in northeast FL. Skies will clear
rapidly from northwest to southeast as drier air advects in the
region with sunny skies developing most locations during the aftn
hours.

Tonight...Much cooler and drier airmass will funnel into the
forecast area with little change in the forecast temps already in
place. Lows expected to dip into mid to upper 30s inland...and in the
40s further east portions that are more affected by boundary layer
winds staying up as the sfc high will remain across TN to the lower
MS Valley. Clear skies and light winds inland may support some light
patchy frost, mainly in wind protected areas.

.SHORT TERM (Monday-Tuesday night)...

High pressure moves across the Carolinas Monday providing a
continuation of the cool and dry conditions with breezy northeast
winds along the coast. The high rapidly moves  moves offshore Monday
night as a short wave trough approaches the area. The return flow
will bring in milder temps with an increase in clouds. A weak
surface low forms and moves along the west Fl gulf coast on Tuesday
before re-developing offshore the Carolinas late Tuesday night.
Isentropic lift...convergence... and large scale ascent from the
trough may lead to locally heavy rain especially south of the I-10
corridor where  1 to 2 inches is possible. Pcp will taper off by
late Tuesday night as both the short wave and surface low lift out
of the area.

.LONG TERM (Wednesday-Saturday)...

While there continues to be some differences between the ECMWF and
GFS...there appears to be some agreement that a a 500 MB low will
close off in the Gulf and track either across Fl or Ga with
cyclogenesis either across central or south Fl. Again...isentropic
lift...convergence... and large scale ascent will lead to rain
across the area with best chances across the cntl and eastern Fl
peninsula. Locally heavy rain is possible especially on Thanksgiving
day although exact amounts will depend on exact track and strength
of the low. Due to cloud cover/pcp and warm sector south of the
area...max temps held to below normal. Confidence continues low on
thunder given the lack of instability and being in cool sector. Long
wave trough will be east of the region by the weekend with high
pressure gradually building in from the gulf coast. Expecting
overall a decrease in clouds Friday with a possible shower early
Friday along the coast then mostly clear by the weekend with max
temps generally in the 60s lows mostly in the 40s.

&&

.AVIATION...Clouds will increase for all terminals due to fast
moving cold front moving in early this morning. MVFR CIGS/VSBY conds
expected to push in between about 10z and 16z along with a chance of
showers. There is an outside chance of IFR CIG roughly from 11z-15z
due to plentiful moisture and shower activity. Have maintained LLWS
for SSI where the low level southwesterly jet is strongest at about
40 kt at 1500 ft through about 10z. VFR conditions will prevail at
the terminals by 17Z. Surface winds southwest through 11z-14z, will
become northwesterly by late this morning after frontal passage,
with winds near 10-15G20knots. Lighter winds expected this evening.

&&

.MARINE...Cold front will enter the coastal waters this morning and
move south of the area by later today. Southwest flow will shift to
northwest in the wake of the cold front. SCA headline is in effect
for the offshore waters for winds around SCA criteria...though
admittedly on the low end of criteria. Have extended the SCA through
early Monday morning based on blend of GFS/NAM guidance. Nearshore
waters may be close to SCA for a time tonight but not too confident
in winds meeting criteria so for now SCEC headline looks good. Sfc
high pres northwest of the front will move to the Carolinas on
Monday resulting in more east-northeast flow. A weak area of low
pressure will develop in the ern Gulf of Mexico late Tuesday and
move east-northeast while high pressure north of the area moves well
east in the Atlantic. Marine weather becomes unsettled Tuesday
through Wednesday with occasional showers expected. Another more
potent low pressure develops Thanksgiving Day just south of the area
and tracks northeast of the region on Friday.

Rip Currents: Low risk today with only small swell activity and
offshore flow. Winds turn more northeast-east on Monday with
increasing threat of rip currents. This trend of increased rip
current concerns will continue through the mid week.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  64  36  65  46 /  10   0   0  10
SSI  67  47  65  57 /  30   0   0  10
JAX  69  43  67  55 /  50   0  10  10
SGJ  71  49  68  59 /  30   0  10  10
GNV  70  39  70  53 /  50   0   0  10
OCF  72  41  72  54 /  50   0   0  10

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...Small Craft Advisory until 3 AM EST Monday for Waters from
     Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-
     Waters from Fernandina Beach to St. Augustine FL from 20 to
     60 NM-Waters from St. Augustine to Flagler Beach FL from 20
     to 60 NM.

&&

$$

Shashy/Peterson



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