Area Forecast Discussion
Issued by NWS Lake Charles, LA

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FXUS64 KLCH 141731
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
1131 AM CST Thu Dec 14 2017

.DISCUSSION...
For 18z TAF issuance.

&&

.AVIATION...
The morning visibility restrictions have since lifted resulting in
VFR conditions at all sites. Winds have begun to slightly increase
areawide but should remain fairly light at less than 5kts.
Expansive cirrus deck has begun pushing into the region, but VFR
should persist through the day. Cold front still expected to move
through the region late this evening. Some lower ceilings with
increasing high and mid level clouds near and after FROPA along
with slightly stronger Nrly winds, but conditions should remain
VFR. Some of guidance suggests some lower visibilities and
possible MVFR at ARA before winds begin picking up behind the
front, but confidence is low on this so have deferred adding any
restrictions to later TAF issuance.

&&

.PREV DISCUSSION... /issued 1009 AM CST Thu Dec 14 2017/

DISCUSSION...
Current forecast is generally on target. Light S/SW SFC winds
ahead of an approaching CDFNT near the I-20 corridor, with
abundant high clouds streaming in from the SW via a moist
subtropical jet. First period grids were tweaked just a bit to
bring them closer to OBs/trends. Forecast highs were also nudged
a little lower owing to the dense cirrus, though they still may
end up too warm.  CDFNT on track to push through the area late
afternoon/early evening.

13

PREV DISCUSSION... /issued 609 AM CST Thu Dec 14 2017/

DISCUSSION...
For 12z TAF issuance.

AVIATION...
Early morning obs show patchy fog across the area, especially over
Acadiana where visibilities were down below a mile at times...
expect this trend to continue through sunrise before improving.
Otherwise just a continuation of VFR with cirrus with light mainly
wrly winds through the expected FROPA late tonight when a slightly
elevated nrly flow should commence.

25

PREV DISCUSSION... /issued 354 AM CST Thu Dec 14 2017/

DISCUSSION...
One more rather pleasant day in store today before a much wetter
pattern develops for the weekend into next week. Increasing
moisture on southerly low level winds will allow temperatures to
rise into the mid to upper 60`s areawide this afternoon despite
the broken high clouds streaming across the region out of the
Pacific.

By late tonight an upper trough will approach the area pushing a
frontal boundary through. While guidance is still consistent in
keeping the best rain chances offshore, isolated to scattered
showers will still be possible Friday morning with the highest
coverage expected near the coast. Behind the front, afternoon
highs will be running about 15 degrees cooler Friday with
overnight lows Friday night once again dipping into the 30s except
along the immediate coastline. The cooler air will be short lived,
however, as the front, which will stall just offshore lifts back
to the north as the next in a series of troughs develops of the
Baja peninsula and swings across the region Saturday into Sunday
bringing numerous showers and a few thunderstorms.

SPC has placed the area in a marginal risk for severe weather
Sunday. Forecast soundings are indicating plenty of low level
shear as the trough ejects northeast, but very little in the way
of instability. So while a stronger storm or two cannot be ruled
out, at least for now the overall severe weather threat is very
low.

Beyond Sunday, guidance begins to diverge considerably and
confidence in the forecast beyond this point is very low. What
seems apparent is that one or more troughs will ride the
subtropical jet across the southern US. The uncertainty comes with
how much moisture is present for these systems to work with. The
wetter GFS leaves a plume of moisture across the region
iPUBLIC...04n the wake of the ejecting trough Sunday night and
thus continues high rain chances Monday into Tuesday while the
operational Euro keeps the moisture offshore Monday before moving
it back into the area by midweek. The Canadian being my tiebreaker
for this forecast sides more heavily with the GFS and thus I went
on the higher side with rain chances through midweek, but the
forecast is a blend of the available guidance (and a few of my own
tweaks) so as not to lean too heavily on any individual solution.

Finally, it is still too early to provide any reliable forecast
for the Christmas weekend or Christmas day (still 11 days away) and
any attempts to do so at this point are futile.

Jones

MARINE...
Light and variable winds will prevail through the day ahead of
our next frontal passage. Showers are expected to accompany this
boundary, followed by a strengthening offshore flow Friday morning.
Rain chances increase once again by late Saturday and into Sunday
as an upper level low moves out of Mexico across the area.

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  62  39  54  33 /   0  10  10   0
LCH  67  44  53  38 /   0  20  20   0
LFT  66  43  52  38 /   0  20  30   0
BPT  68  45  54  39 /   0  30  20   0

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&

$$


AVIATION...50



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