576
FXUS64 KLCH 131235
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
735 AM CDT Mon May 13 2024

...New AVIATION...

.SYNOPSIS...
Issued at 407 AM CDT Mon May 13 2024

An active pattern continues tonight, with a strong storm moving
east across the Lakes Region toward western LA. Additional scattered
showers and an isolated storm or two are noted on KLCH/KPOE
radars across the area. Regionally, multiple convective clusters
are noted across the central and N LA into MS. These storms
remain rather potent, even without the added energy of daytime
heat, thanks to a rather robust impulse crossing the region aloft.
The latest WV imagery and UA analysis shows the main low system
driving this extended active pattern spinning over SW KS as it
moves slowly east. South of this feature, an active subtropical
jet continues to supply copious moisture over the area, while
lower in the atmosphere, elevated southerly winds continue to
advect Gulf moisture northward.

At the surface, a warm front is draped from inland SE TX (north of
I-10 east and southeast toward the lower Atchafalaya Basin). North
of this front, temperatures remain in the middle to upper 60s,
while to the south, a warm and muggy airmass has returned with
temperatures in the upper 70s and dewpoints only a degree or two
lower.

A Flood Watch remains in effect for today north of the I-10
corridor to Hwy 190 corridor in LA. Radar estimated rain amounts
of at least 2 inches fell across much of the flood watch area
yesterday, with localized amounts of up to 4-5 inches. The area
remains in a Slight Risk (level 2 out of 4) for excessive rainfall
today. But perhaps the greater concern for today will be severe
weather, and SPC has recently upgraded their Day 1 outlook to an
Enhanced Risk (level 3 out of 5), with damaging wind gusts and
large hail the primary threats.

24

&&

.SHORT TERM...
(Today through Wednesday night)
Issued at 407 AM CDT Mon May 13 2024

The mid/upper low and its attendant surface reflection will
slowly migrate east across the central US. This will lift the warm
front further inland, allowing a more buoyant warm sector to
overspread the area. Warming in the lower levels will provide
substantial destabilization today, with surface based CAPE values
increasing to 3000-4000+ J/kg while midlevel lapse rates steepen
to 8+ C/km. Enhanced midlevel westerlies translating over the
region amid of series of perturbations aloft, will provide
sufficient deep layer shear to support organized updrafts once
convection initiates by midday across portions of central/SE TX.

CAM guidance suggests convection will evolve into a squall
line/MCS as it progresses east into our area later this
afternoon/evening. Timing and overall coverage remain somewhat
uncertain however, and CAMs have struggled with convective
initiation/evolution in this rather complex pattern. Given the
strong midlevel lapse rates, there is a significant risk (greater
than 10%) for hail larger than 2 inches across the area. This will
be in addition to the potential for damaging wind gusts within any
bowing segments as well as a few isolated QLCS-type tornadoes.

Beyond the risk for severe weather, there is an ongoing concern
for flooding. While the axis of extreme PWATs (greater than 2
inches) looks to shift east toward SE LA, values over the region
will continue to be between 1.7 and 1.9 inches (still at least 2
standard deviations from the mean). This will support efficient
rainfall production with high rainfall rates within some of the
storms. HREF LPMM rain accumulations indicate multiple 1 to 3
inch swaths across the area (with localized higher amounts).
Again, there is some uncertainty regarding where these belts of
higher rain totals could set up and CAM storm total solutions
vary quite a bit. At this time, will opt to leave the Flood Watch
as it is, but an extension southward may be needed should the
axis shift closer to I-10 (as the HRRR seems to indicate).

The last of the convection for this round should be exiting to the
east late tonight into the overnight hours as the main trough axis
moves into the region. The passage of this low system will drag a
weak cold front through the area on Tuesday, allowing for a much
needed but short-lived break in the wet pattern. Any coolness
associated with the front will be felt mainly overnight, with
lows possibly falling into the lower to middle 60s by Wednesday
morning. Otherwise, daytime temperatures will remain near or even
warmer than normal, with the potential for highs around 90 degrees
across southeast TX on Wednesday.

Unfortunately, the next round of rain will return to our doorstep
Wednesday night as the next disturbance moves toward the region.

24

&&

.LONG TERM...
(Thursday through Monday)
Issued at 407 AM CDT Mon May 13 2024

Precip chances return Thursday as a warm front lifting North out of
the gulf is overrun by a couple of disturbances aloft ahead of a
cold front that will then push through the region over the weekend.
Guidance has been in consistently good agreement on deep moisture
pooling with forecast PWAT values climbing to near or slightly above
2 inches. This will allow for rounds of torrential rainfall that
could lead to flash flooding especially across parts of Southeast
Texas that have seen well above normal rainfall this spring. There
is more uncertainty regarding the timing of the end of the precip
following fropa. The most widespread activity looks to be Thursday
through Friday morning with the better upper level energy, but the
moisture will remain in place until the fropa sometime Saturday
afternoon to Sunday morning.

The airmass behind the front won`t be appreciably cooler or drier as
it`s getting rather late in the season for airmass changing cold
fronts, but it will scour out the moisture aloft bringing precip to
an end through early next week.

Jones

&&

.AVIATION...
(12Z TAFS)
Issued at 656 AM CDT Mon May 13 2024

A band of scattered showers trails behind a strong storm that
crossed the area overnight, passing well south of the AEX
terminal. Some of these showers could affect the LFT and possibly
ARA terminals this morning, but otherwise convection should be
minimal through midday. MVFR vsbys/IFR cigs prevail at LCH/BPT,
with MVFR cigs at LFT/ARA and VFR at AEX. Expect a general
improvement to VFR through midday into early afternoon, with
another round of SHRA/TSRA moving into the area during the
afternoon and evening. This activity will likely be in the form of
a squall line, with damaging wind gusts and very heavy rainfall
possible, along with cigs/vsbys falling to IFR/LIFR. A brief
period of elevated NW-N winds will be possible in the wake of the
squall line. Convection will end from west to east after 03Z,
likely exiting the Acadiana terminals by 08-10Z, with IFR cigs
and patchy MVFR fog likely to develop.

24

&&

.MARINE...
Issued at 407 AM CDT Mon May 13 2024

Moderate southerly winds will continue through tonight, but
should relax below exercise caution levels this morning. Shower
and thunderstorm chances are expected to increase later today
into tonight. A few strong to severe storms will be possible, with
strong wind gusts, large hail and isolated waterspouts possible.

Winds will shift westerly on Tuesday, then offshore Tuesday night
with the passage of a weak cold front. Winds will turn back to the
east and southeast by Wednesday night, with rain chances
returning by Thursday as another low pressure system approaches
the area.

24

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  82  64  86  61 /  70  50   0   0
LCH  83  67  88  65 /  60  50  10   0
LFT  85  70  89  68 /  80  70  10   0
BPT  85  68  89  66 /  60  50   0   0

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...Flood Watch through Tuesday morning for LAZ027>032.

TX...Flood Watch through Tuesday morning for TXZ180-201-259>262.

GM...None.
&&

$$

SHORT TERM...24
LONG TERM....66
AVIATION...24