Area Forecast Discussion
Issued by NWS Lake Charles, LA

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066
FXUS64 KLCH 160338
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
938 PM CST Sun Dec 15 2019

.UPDATE...
In the short term, the 16/00Z upper air sounding from KLCH shows a
cap in place around 85H, and would expect this to hold through the
night. Therefore, any shower activity should be the light streamer
type under the cap and adjusted pop and weather grids to account
for this and latest hi-res guidance. Winds look to stay up enough
tonight to preclude any wide spread fog. However, some patchy sea
fog may begin to develop during the overnight as the very moist
air moves over the cooler shelf waters, and added that to the
weather grids.

Still looking for a significant cold front to move across the
forecast area, on Monday. Front is expected to enter the forecast
area in upper southeast Texas in the late morning, then progress
eastward and through the forecast area by early evening. Frontal
lift and daytime heating ahead of the front, should be enough to
overcome any capping and allow for convective bands to develop
ahead of the cold front.

Shear numbers looking good and what is usually the case for the
cool season, instability will play the role as to to how strong to
severe the storms will get. At this point, it does look like good
destabilization will take place in the afternoon hours, especially
away from the coast and away from the modified marine layer, with
most unstable CAPE values progged to reach between 1500 and 2000
j/kg across central Louisiana, as well as interior southwest and
south central Louisiana.

Therefore, the best time for the potential of severe storms will
be from shortly after noon time to around 6 pm, with air mass
becoming more stable shortly after sunset. The best location for
the severe potential will be east-northeast of a Leesville to
Lake Charles line. The main severe weather mode is expected to be
straight line damaging wind gusts along the convective band ahead
of the front, although some embedded cells within the band or a
discrete cell or two that can get going ahead of the band may
produce large hail and/or a quick spin-up tornado.

Hazards currently in effect are marine related and for the strong
north winds expected behind the cold front late Monday into
Tuesday and are unchanged at this time.

Rua

&&

.PREV DISCUSSION... /issued 538 PM CST Sun Dec 15 2019/

DISCUSSION...
00Z TAFS

AVIATION...
Prevailing VFR CIGs across the region are expected to gradually
lower to MVFR over the next couple of hours with the loss of
daytime heating. Winds are also expected to weaken somewhat, but
will remain strong enough to prevent any fog formation overnight.

Isolated to scattered showers will develop beginning after
midnight in advance of an approaching cold front that will move
through the area from mid morning through late afternoon.
Scattered to numerous thunderstorms will develop ahead of the
front with a squall line expected to form on the leading edge.
Damaging winds and large hail will be possible within the squall
line. Winds behind the front will turn out of the northwest and
increase once again late Monday.

Jones

PREV DISCUSSION... /issued 355 PM CST Sun Dec 15 2019/

DISCUSSION...
Partly to mostly cloudy skies this afternoon did
not do enough to hinder the strong warmup to above
normal temperatures. In fact...several spots did manage
to hit 80 degrees this afternoon including Beaumont...Lake
Charles...Jasper and Esler Field. The average high is around
64 degrees...so that is 16 degrees higher than normal.

The rapid warmup began right after the fog burned off across the
area in response to a falling pressure across the region due to an
approaching strong upper level storm system which will move into
the plains on Monday. Sustained winds were mostly below 20 knots
in most locations...however the real story was the gusty
southerly winds which reached up to 32 mph in parts of Louisiana.
Gusty winds in the upper 20s were common.

Going forward now...looks like gulf moisture moisture will
continue to feed into southeast Texas and Louisiana on continued
light to moderate southerly flow tonight. There could be some
patchy fog again tonight after midnight but the airmass will
likely continued to be stirred up...therefore...banking on low
clouds to be the main concern tonight along with possible showers
and thunderstorms later tonight as the system approaches.

The Storm Prediction Center has our area in a slight to enhanced
risk areas overnight into Monday as the sounding profiles suggests
rapid destabilization and elevated helicities which will likely
transition ordinary thunderstorms into supercells ahead of the
line Monday morning into the afternoon and evening with QLCS line
of storms with the actual front. In this area...we do see rapid
spinup of brief tornadoes within QLCS lines along with damaging
winds. The zone forecast...and other products along with our
digital grids will include this severe weather wording on Monday
to better advertise the threat.

Once the front moves across the area on Monday and Monday night...
we do expect the rain to end behind the front with strong high
pressure building to the region.

Stable weather will stick around until early morning Friday
before the next system and front approaches the area. Rain chances
will briefly spike on Friday but the frontal passage Friday night
should allow for high pressure and stable conditions to settle in
just in time for the weekend next week.

As for temperatures...look for one more day on Monday for above
normal temperatures in the mid to upper 70s areawide. Then...the
remainder of the week will be below normal in the mid to upper 50s
with a slight warmup to near normal temperatures by the very end
of the 7 day period ending sunday. Lows in the lower 30s can be
expected Wednesday and Thursday mornings northern areas north of
the I10 corridor. However...we should stay above freezing for
overnight lows along and south of the I-10 corridor...perhaps in
the mid 30s for lows.

MARINE...
Went ahead and issued a Gale Watch for the nearshore and outer
waters Monday night into Tuesday along with Small Craft Advisory
conditions for the lakes and bays as the cold front sweeps across
the coastal waters and strong high pressure builds in. Winds and
waves will be too high for small craft during the Gale Watch
period.

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  65  76  38  52 /  40 100  40   0
LCH  67  78  41  53 /  30 100  40   0
LFT  66  78  43  51 /  30 100  70   0
BPT  68  77  41  54 /  30 100  30   0

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...Gale Watch from Monday evening through Tuesday afternoon for
     GMZ450-452-455-470-472-475.

     Small Craft Exercise Caution through Monday afternoon for GMZ470-
     472-475.

     Small Craft Advisory from 6 PM Monday to 6 PM CST Tuesday for
     GMZ430-432-435.

&&

$$

PUBLIC...07



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