237 
FXUS64 KLCH 210940
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
340 AM CST Tue Jan 21 2020

.DISCUSSION...
Early morning sfc analysis shows high pressure centered over the
Missouri Valley ridging swd, providing a light nerly flow over the
forecast area. Water vapor imagery shows troffing in place over
the ern CONUS with ridging developing behind it over the
Plains/lee of the Rockies...this is resulting in a dry nwrly flow
aloft over the region. Other than a little cirrus spilling over
the ridge and spreading over the area at this time, skies are
clear thanks to a general lack of moisture through the column per
regional 00z soundings with PWATs running below climo normals and
MRH values running about 30-50 percent of normal. As expected,
regional 88Ds are PPINE this morning. Main issue this morning is
the likelihood of frost, especially across the nrn zones where
temps have fallen to the lower/mid 30s (KESF has dropped all the
way 28F at 09z) with calm winds.

No problems anticipated in the short-term with dry high pressure
holding on for at least the first period. As we move into tonight,
the sfc high shifts ewd, allowing a bit of a low-level return flow
to set up, especially over the far wrn zones. After our cool
start, temps will run a bit cooler than Monday, especially the
swrn zones where highs ran a little higher than expected
yesterday. Mins tonight should be a few degrees warmer than this
morning.

Deeper moisture begins to spread over the forecast area tomorrow
with the sfc high now east of the region and the initial
disturbance rounding an approaching trof axis brings in Gulf
moisture aloft. The combo of these features should allow for the
onset of shower development in the morning over the far wrn zones,
with an ewd progression through the afternoon (perhaps holding off
til the evening for the Atchafalaya Basin for now). An approaching
upper-level speed max and a developing sfc low over sern TX/nwrn
Gulf will enhance lift starting Wednesday evening, with much of 
the area under categorical POPs for the night and on into Thursday
morning. As of now, best instability is progged to remain closer
to or off the coast although with the sfc low eventually expected
to move newd across the forecast area, instability may be
sufficient enough, along with good mid-level lapse rates/shear, 
to produce a few storms mainly Thursday. As the trof axis/sfc
boundary sweep ewd through the area accompanied by much drier air,
expect the showers/storms to gradually end from west to east late
Thursday afternoon and evening.

Dry conditions look on tap for Friday and Saturday as sfc high
pressure and wrly flow aloft briefly settle over the area. Friday
and Friday night look seasonal temp-wise before the high moves
east in our progressive pattern and a slight warmup commences.

Some subtle differences are noted again in the models this morning
pertaining to another weak system impacting the area late in the
weekend, thus slim POPs are being carried in the interim. The
period ends on a dry note for Monday/Monday night as this feature
slips past the region and drier air on sfc high pressure/ridging
aloft returns.

&&

.MARINE...
Extended the caution headlines for the outer waters into the
afternoon as guidance paints winds slowly falling through the
15-20 knot range. After a brief diminishing of winds for tonight,
caution conditions look likely again for Wednesday as the gradient
tightens with low pressure deepening over the Plains. Winds
continue to strengthen through Wednesday night with SCA conditions
likely as sfc low pressure develops nearby. Once the whole mess
moves out on Thursday, a brief period of elevated offshore flow
can be expected in its wake.

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  49  31  48  42 /   0   0  30  80 
LCH  52  36  52  49 /   0   0  60  80 
LFT  50  35  54  49 /   0   0  10  60 
BPT  54  40  55  53 /   0  10  80  90 

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...Small Craft Exercise Caution through this afternoon for GMZ470-
     472-475.

     Small Craft Exercise Caution until 6 AM CST early this morning 
     for GMZ450-452-455.

&&

$$

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