Area Forecast Discussion
Issued by NWS Lake Charles, LA

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FXUS64 KLCH 030041
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
641 PM CST Fri Dec 2 2016

.Discussion...
For the 02/00Z Taf Issuance.

&&

.Aviation...
Southwesterly flow aloft overrunning cooler air at the surface
generally resulting in overcast conditions with some light rain or
shower activity. Clouds are still in the VFR range with lowering
to around 5K feet at a few locations. MVFR likely will begin
tomorrow morning after 12Z and deterioration likely to continue
through the day as low surface low pressure develops over the
Texas coastal area resulting in showers and thunderstorms
developing through the day here on Saturday. Easterly winds
tonight will begin to strengthen and remain gusty into Saturday
as the above mentioned surface low tightens up.

&&

.PREV DISCUSSION... /issued 424 PM CST Fri Dec 2 2016/

..Added Event Rainfall Totals in the Discussion Section...

SYNOPSIS...
Surface analysis shows a coastal trough over the Northwest Gulf of
Mexico from roughly off the South Central Louisiana coast to just
off the Lower Texas coast. Meanwhile...water vapor imagery shows
an upper level low over the Baja Peninsula with increasing moist
southwest flow ahead of this system across Northern Old Mexico
through Texas into the Gulf South. Local radars showing the
initial area of mainly light rain and sprinkles moving into the
forecast area.

Rua

DISCUSSION...
Looking like the ingredients for a long duration rainfall event
for portions of the forecast area setting up. The upper level low
will move slowly across the Baja Peninsula into Northern Old
Mexico this weekend, and will not kick out until Monday. The
surface coastal trough will continue just offshore the Louisiana
and Texas coast. Increasing flow mid and upper level flow will
transport elevated East Pacific moisture, with low level flow
transporting elevated Gulf of Mexico moisture. This moisture will
be lifted over the coastal trough producing periods of over-
running shower activity until the upper level low finally kicks
out.

Moisture will be elevated through this event, with Precipitable
Water values increasing to 1.50 to 1.75 inches tonight...roughly
over 150 percent of norm...then between 1.75 to 2 inches...or
over twice the standard deviation...on Saturday into Sunday. With
these moisture values...combined with the increasing upper level
divergence aloft...the potential of some decent rainfall amounts,
with pockets of heavy rainfall will exist.

Still tough to say where the heavy rainfall pockets will be.
Mostly likely close to where the best 1000mb-850mb convergence
will be and where elevated instability will provide a chance for
elevated convection and heavier rainfall. For tonight into
Saturday, this looks to take place over Southeast Texas into
extreme Southwest and West Central Louisiana before moving
eastward throughout the forecast area on Sunday. Severe weather
threat looks minimal at this point with low level and surface
based instability on the low side through Sunday.

Event will come to an end on Monday. As the upper level low kicks
out, a surface low will develop along the coastal trough and move
northeastward. This will wiggle the coastal trough north as a warm
front, with the potential for the southeastern portion of the
forecast area getting into the warm sector. Therefore, there will
be a chance of severe storms during Monday afternoon as the
surface low move across the forecast area and thunderstorms could
become more robust with the increasing instability.

Rainfall totals for this event through Monday will range from 3 to 6
inches with locally higher amounts. On average the higher amounts
will be over Southeast Texas into West Central and Southwest
Louisiana.

Drier air will move in on Tuesday, behind the departing low. A
strong cold front will move across late Wednesday, with a few
showers developing out ahead of it.

A cold Canadian air mass will settle over the region late next
week behind the cold front. Lows on Thursday Night/Friday Morning
and Friday Night/Saturday Morning look to be below freezing
possibly down to the I-10 corridor and some upper 20s for the
northern zones.

Rua

AVIATION...
For the 02/18Z TAF issuance...
Expect rain to increase and become more steady throughout the
night. Ceilings/Visibilities at first will be VFR Levels, then
gradually reducing to MVFR during the overnight into early
Saturday.

Rua

MARINE...
A coastal trough at the surface will strengthen off the Texas
coast tonight. This will allow for easterly winds to increase to
20 to 25 knots with gusts close to Gale Force through the night
into Saturday. A Small Craft Advisory will be in effect. Also,
with the easterly winds, tidal piling up will be possible along
the Southwest Louisiana and Southeast Texas coast tonight...with
tide levels 1 to 1.5 feet above predicted levels and actual tide
readings at high tide near 3.0 to 3.5 feet mllw. Therefore, some
minor coastal flooding may take place and a Coastal Flood Advisory
will be in effect for that area.

Winds will become westerly late Monday, as a surface low develops
along the coastal trough and kicks the system off to the east.

Rua

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  47  53  49  56 / 100 100  80  80
LCH  52  65  59  67 / 100 100  70  80
LFT  52  66  61  72 / 100  70  60  80
BPT  54  65  59  67 / 100 100  80  80

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...Wind Advisory until 6 AM CST Saturday for LAZ052-073-074.

     Coastal Flood Advisory until 6 AM CST Saturday for LAZ052-073-
     074.

TX...Wind Advisory until 6 AM CST Saturday for TXZ215.

     Coastal Flood Advisory until 6 AM CST Saturday for TXZ215.

GM...Small Craft Advisory until 6 PM CST Saturday for GMZ450-452-455-
     470-472-475.

     Small Craft Advisory until 6 AM CST Saturday for GMZ430-432-435.

     SMALL CRAFT EXERCISE CAUTION from 6 AM CST Saturday through
     Saturday afternoon for GMZ430-432-435.

&&

$$

PUBLIC...04


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