Area Forecast Discussion
Issued by NWS Lake Charles, LA

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FXUS64 KLCH 180358
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
958 PM CST Fri Nov 17 2017

.UPDATE...
Well this is the last night where temperatures will hover in the
mid to upper 60s around sunrise. Currently Lake Charles is at
71... POE 70... BPT 72....AEX 69.... LFT 69... Tonight will see a
bit of fog but nothing like we have had the last several mornings.
But the real story is the frontal system expected to move through
the area tomorrow aftn. You will not miss this front although
temps will get back into the 80s prior to frontal passage. Aftr
the frontal passage look to see temps dropping thru the late
afternoon hours. There will be a chance for showers and isolated
thunderstorms. Sunday morning upper 40s.

But for tonight the zones look fine.

&&

.PREV DISCUSSION... /issued 608 PM CST Fri Nov 17 2017/

DISCUSSION...
18/00Z TAF Issuance.

AVIATION...
Wind gusts are beginning to diminish acrs the area although
southerly winds will remain between 7-12 KT overnight. This should
help keep fog development at bay, and instead allow for the
formation of MVFR cigs after 06Z. Winds will strengthen again
Saturday morning, bcmg southwesterly ahead of a cold front that
will move through late in the day. Expect sustained speeds
12-17 KT with gusts 20-25 KT. A few -SHRA will be possible,
mainly along the frontal boundary as it moves through the
northwestern half of the area, reaching roughly an AEX-LCH line
by 00Z. Winds will continue to be strong behind the front,
shifting west to northwest, while cigs will lift to VFR.

24

PREV DISCUSSION... /issued 334 PM CST Fri Nov 17 2017/

SYNOPSIS...
Gradient and flow between surface ridge along the east coast and
low pressure over the Southern Plains is producing breezy south
winds today helping to produce another warm and humid November
day. Meanwhile, water vapor imagery shows an upper level
disturbance moving out of the Pacific Northwest into the Northern
Plains.

Rua

DISCUSSION...
Gradient should allow southerly boundary layer winds to stay up
in the 15 to 20 knot range, with surface winds near 10 knots
tonight. Therefore, not expecting much in the way of fog
development. The moist flow off the Gulf should result in a warm
and muggy night with a low cloud overcast for the forecast area.

Still decent agreement with upper level disturbance moving out of
the Pacific Northwest to move across the Northern Plains to the
eastern US over the weekend as an amplifying short wave. This will
help a Canadian cold front to move across the forecast area from
late Saturday afternoon and early Saturday evening. The overall
moisture profile is not all that impressive with Mean RH in the 50
to 60 percent range and PWAT around 1.3 inches. However, decent
low level convergence and frontal lift should be enough to produce
scattered showers ahead of the front. Instability still looks
rather weather weak ahead of the front, with best upper level
dynamics well off to the northeast. Therefore, will keep the
predominate weather as showers with no mention of thunder at this
time.

A much cooler and drier air mass will then move in behind the
front for the remainder of the weekend. Surface ridge looks to
settle across the forecast area on Sunday night, and this will
likely provide rather chilly temperatures, with mid 30s for
Central Louisiana and the Lakes Area of Southeast Texas, with
upper 30s possible down to the usual cool spots of the I-10
corridor.

Surface ridge will move off to the east on Monday with some return
flow moisture and a moderation in temperatures.

Better agreement today in guidance for Tuesday through the
remainder of the Holiday week. The next Canadian cold front is
expected on Tuesday night. Operational ECMWF still looks to be on
the high end of the ensemble range when it comes to being too
robust on the return flow moisture and thus the pops for Tuesday
into early Wednesday. Therefore, will again go a little below
Superblend numbers for those days and closer to a ECMWF ensemble
mean/GFS compromise, which would bring low end chance pops for
Tuesday daytime, with a gradual decrease in pops Tuesday night
into Wednesday morning.

Guidance is also in better agreement with sweeping the front out
into the Gulf for Thanksgiving into next Friday, thus keeping
better moisture and any Gulf low development further to the south
and east of the forecast area. Therefore, a dry and rather cooler
Turkey day into Friday looks to be in the works.

Rua

MARINE...
Low pressure over the Southern Plains is helping to increase the
gradient across the forecast area and producing breezy southerly
winds. The moderate onshore winds will continue for tonight into
Saturday with wind speeds between 15 and 20 knots. Therefore, will
have the Small Craft Exercise Caution headline for the coastal
waters forecast.

A Canadian cold front will move across the coastal waters on early
Saturday Evening. With good cold air advection moving over
relatively warm Gulf waters, decent mixing should occur allowing
for strong and gusty north winds to develop. Sustained winds
overnight Saturday into Sunday should be 25 to 30 knots with
definite Small Craft Advisory conditions. Gusts over Gale force
to near 40 knots will be possible, so there is also the
possibility that a Gale Watch/Warning may be issued using the
frequent gust criteria.

Winds will begin to decrease Sunday night as the high pressure
system behind the cold front settles across the coastal waters.

Rua

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  66  80  41  62 /  10  30   0   0
LCH  69  80  47  64 /  10  30  10   0
LFT  67  81  47  63 /   0  30  20   0
BPT  67  81  46  65 /  10  30  10   0

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...Small Craft Exercise Caution through Saturday afternoon for
     GMZ450-470-472-475.

     Small Craft Exercise Caution from 6 AM CST Saturday through
     Saturday afternoon for GMZ452-455.

&&

$$

PUBLIC...19



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