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000
FXUS64 KLCH 201156
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
656 AM CDT Sat Apr 20 2024

...New AVIATION...

.SYNOPSIS...
Issued at 428 AM CDT Sat Apr 20 2024

Warm and muggy conditions are noted across the area, south of a
frontal boundary draped across central LA into E TX. Moisture
continues to increase across the region, with PWATs up to around
1.5 inches per the KLCH 00Z sounding.

Latest UA analysis and WV imagery shows a swath of moisture
streaming across across TX toward the lower MS Valley, which was
occurring ahead of a shortwave trough over the SW US. This was
yielding widespread cloud cover across the area, while a few light
showers were noted on KLCH radar across central and southern LA.

The combination of low clouds and patchy fog will continue through
the early morning hours, with a few sprinkles in the mix as well.
But the better rain chances are not expected to affect the area
until late this afternoon into this evening as the SW US trough
moves closer to the area.

24

&&

.SHORT TERM...
(Today through Monday night)
Issued at 428 AM CDT Sat Apr 20 2024

Rain chances will remain generally limited early today, although a
few light showers cannot be ruled out. Broad ascent will begin to
develop later today as the shortwave trough moves into TX, with
convection forming and spreading into SE TX during the afternoon.
Convection will continue to spread east across the area during the
evening and overnight hours as more robust lift accompanies the
trough as it moves into the region. The frontal boundary will
slowly meander south, and most of the convection that develops
should remain elevated to the north side of the boundary.

Severe parameters (lapse rates, instability) appear greatest this
afternoon, but the better support for deep convection will be
focused west of the area. However, an isolated strong storm
capable of strong winds or isolated hail could slip into our SE TX
counties before weakening late this afternoon or early evening.
Otherwise, forecast soundings show increasing deep layer shear
developing during the evening and overnight as a midlevel speed
max translates over the area. This should be sufficient to support
updrafts capable of producing thunder, but lapse rates and
instability appear too limited to generate stronger storms with
the arrival of the disturbance aloft.

The risk for heavy rainfall and possible isolated to widely
scattered instances of flash flooding continues to be the primary
hazard tonight into early Sunday. Moisture will be plentiful with
PWATs increasing to 1.7-1.8 inches (well above the 90th
percentile and close to the seasonal maximum). Storms will be
capable of producing heavy rainfall with high precipitation rates.
While convection should be fairly progressive, there is the
potential for some training as storms track along and just north
of the quasi-stationary surface boundary. The axis of highest QPF
remains oriented from SE TX north of the Houston metro northeast
across N LA, but any deviation southward would place these higher
amounts of 2+ inches into our region (where heavy rainfall
occurred last week). The latest WPC ERO for Day 1 now paints areas
northwest of a line from Alexandria to Sour Lake in a SLGT risk
(level 2 out of 4) for excessive rainfall, with a MRGL (level 1
out of 4) elsewhere with the exception of the Acadiana region. At
this point, have opted not to issue a Flash Flood Watch for our
parishes and counties in the SLGT risk area as deterministic NBM
QPF remains relatively low (storm totals between 1-1.5 inches
across our northern tier of zones), while CAM guidance and HREF
probs for 2+ inch amounts suggest an isolated risk.

Convection will shift east across the area by Sunday morning, with
rain chances tapering off from west to east through the afternoon
as the trough moves east of the lower MS Valley. This trough,
along with a northern stream shortwave digging southeast in its
wake, will help propel the front offshore and allow much cooler
high pressure to build into the region. This will lead to some
brisk northeast winds on Sunday, while lingering cloud cover and
decent CAA will keep high temperatures in the middle to upper 60s
across all but the immediate coast. Some of the coolest
temperatures of the period will occur Sunday night into Monday
morning as the ridge axis slides over the region, with lows
falling into the lower 40s across central LA, and to around 50
degrees along the I-10 corridor.

Dry weather will prevail into the early part of the workweek, with
temperatures expected to rebound into the 70s Monday afternoon
under mostly sunny skies.

24

&&

.LONG TERM...
(Tuesday through Saturday)
Issued at 428 AM CDT Sat Apr 20 2024

The long-term forecast will start with the region firmly under the
influence of high pressure. After the passage of the cold front on
Sunday, cold air advection will push a continental airmass into our
region. This will lead to slightly cooler than average temperatures
on Tuesday, with highs in the upper 70s and lows still in the 50s.
For those who enjoy cooler weather, enjoy it while it lasts.

On Wednesday, our winds will have flipped, and warm, moist Gulf air
will be pulled north across the southeastern US. Winds will remain
onshore for the rest of the forecast period, and we will see robust
moisture return with our PWATs going from the bottom 10th percentile
on Tuesday to the 75th percentile by Thursday. Temperatures will
also rise, with highs in the mid- to upper-80s for the rest of the
forecast period. Low will also rise, reaching the 70s by midweek. A
few weak short-wave troughs will increase rain chances throughout
the week, but not by much, with PoPs staying below 30%. This week,
we could start to see the return of diurnally driven showers and
thunderstorms. 

14/Slaughter

&&

.AVIATION...
(12Z TAFS)
Issued at 643 AM CDT Sat Apr 20 2024

Low clouds and patchy fog are making for a variety of conditions
this morning, from MVFR down to LIFR at times. Mixing after
sunrise should allow fog to dissipate with cigs lifting to MVFR or
VFR by mid to late morning at the southern terminals. Further
north, IFR cigs and a few isolated SHRA are expected at AEX due
to the proximity of a nearby stationary front. Cigs will begin to
lower again this evening, with SHRA becoming more widespread
(along with some embedded isolated TSRA) during the overnight
period as a disturbance moves through the region. The front will
shift toward the coast overnight, with winds becoming northerly
around 10 KT at all sites by the end of the period.

24

&&

.MARINE...
Issued at 442 AM CDT Sat Apr 20 2024

Light to moderate east to southeast winds can be expected today,
as a weak frontal boundary meanders slowly south over the region.
Showers and a few thunderstorms will increase tonight into
Sunday as a disturbance aloft moves into the area. The front will
move offshore by early Sunday, with strong offshore winds
developing in its wake Sunday morning and continue into early
Monday before diminishing. Small Craft Advisories are expected to
be in effect during this timeframe. Winds will diminish through
the day Monday, with onshore flow redeveloping by Tuesday as
surface high pressure moves over the eastern seaboard.

24

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  72  49  64  43 /  30  90  40   0
LCH  83  56  67  50 /  40  60  30   0
LFT  85  59  67  50 /  30  60  50   0
BPT  83  56  69  50 /  30  70  20   0

&&

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

$$

SHORT TERM...24
LONG TERM....14
AVIATION...24