557
FXUS64 KLCH 121153
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
653 AM CDT Sun May 12 2024

...New AVIATION...

.SYNOPSIS...
Issued at 436 AM CDT Sun May 12 2024

WV imagery and UA analysis shows an active subtropical jet
transporting moisture across old Mexico into the NW Gulf states.
To the north of the jet, a large mid/upper low system continues to
spin over the southern CO. Meanwhile, the surface pattern across
the region is marked by a generally weak wind field, with high
pressure centered just east of the area and a frontal boundary
situated just off the coast. Conditions are generally on par with
where they were 24 hours ago, with temperatures in the middle 60s
to lower 70s and dewpoints in the lower 60s. KLCH and KPOE radars
show a band of convection persisting across our northern zones,
with some lighter showers further south, although activity has
diminished some since a few hours ago.

This activity marks the beginning of what is expected to be a
fairly active period today through Monday night. This will
unfortunately result in more rainfall for areas that really do not
need it, namely portions of SE TX and SW LA north of I-10. The
latest Day 1 outlook from WPC now includes a Moderate Risk (Level
3 out of 4) for portions of SE TX into W LA, with a Slight Risk
(Level 2 out of 4) across all but the Acadiana region. A Flood
Watch has been issued for Hardin and Tyler Counties east to
Beauregard and Vernon Parishes in SW LA, with the watch in effect
through Tuesday morning as multiple rounds of rainfall are
expected.

24

&&

.SHORT TERM...
(Today through Tuesday night)
Issued at 436 AM CDT Sun May 12 2024

The low pressure system over the Rockies will slowly emerge over
the KS plains today through tonight, helping to generate a weak
surface low over the southern plains. As this low takes shape, it
will help lift the frontal boundary near the coast northward as a
warm front. Strengthening 850 MB jet will support moisture
transport over the region, with PWATs progged to increase to near
2 inches through tonight (well above the 90th percentile and
nearly 2 to 3 standard deviations from the mean). PWATs could
increase further on Monday, with guidance suggesting values as
high as 2.2-2.3 inches.

For today, convection is expected to focus along the warm front
as it moves inland across SE TX into SW LA. Sounding profiles show
deep moisture, strong deep layer shear and sufficient instability
to support storms capable of both heavy rainfall and severe
weather. In addition to the aforementioned MDT risk of excessive
rainfall, there is a SLGT risk for severe storms as well, with the
primary threat damaging wind gusts. If storms can become surface
based, sufficient low level helicity would support an isolated
tornado or two.

A brief respite is expected this evening and overnight, with
another round of convection expected on Monday as the upper low
slowly crosses KS toward the mid MS Valley. As the warm front
lifts further inland, the region will become entrenched within the
warm sector, with instability becoming much more robust over the
area. This combined with deep layer shear will provide favorable
conditions for a few strong to severe storms to develop Monday
afternoon across SE TX. This activity is expected to progress east
into the evening. Damaging wind gusts and hail will be the
primary threats, and SPC has outlined the entire area in a SLGT
risk. Meanwhile, the heavy rain threat will also continue across the
area, as the atmosphere remains anomalously moist. PWATs are
progged to exceed 2 inches, which would allow for storms capable
of high rainfall rates on top of today`s rain.

While guidance hasn`t fully aligned with respect to the axis of
highest rainfall amounts, recent CAM guidance suggests a swath of
higher QPF totals across the region marked by the Moderate ERO
today. HREF LPMM precip accumulations depict amounts between 2
and 4 inches through Monday evening, but training cells and
redevelopment could produce localized amounts of 6 inches or
greater.

Convection should begin to taper off considerably late Monday
night into Tuesday morning as the lead impulse moves east. A weak
cold front is expected to move through the region on Tuesday,
allowing for a short-lived break in the wet pattern.


&&

.LONG TERM...
(Wednesday through Sunday)
Issued at 436 AM CDT Sun May 12 2024

Welcome dry weather expected to start the period on Wednesday.
Moisture begins to return late Wednesday into Wednesday night as
high moves off to the east. As the next disturbance moves into the
region early Thursday the signals for heavy rainfall returns to
the region as PW`s get above 2 inches. While much of the area is
under the risk for very heavy rainfall most signals continue
across Southeast Texas and Southwest Louisiana which have been hit
by multiple rounds of heavy rainfall the past month and half.

The GFS is by far the driest model for Thursday and has waffled from
last night while the ECMWF and the CMC remain bullish on
precipitation. Questions also still remain on what happens Friday
into Saturday as the front slows. The GFS has this as the period of
heavier rains while ECMWF moves most of the activity to the east.
For now blends have lower POPS Friday and Saturday, but things could
tend more wet with future updates.

Temperatures will be slightly below seasonal norms through Thursday
then trend warmer than normal the remainder of the period.

27

&&

.AVIATION...
(12Z TAFS)
Issued at 640 AM CDT Sun May 12 2024

VFR conditions have prevailed across the area this morning,
although the latest ob at BPT suggests some MVFR cigs are
beginning to manifest across lower SE TX into SW LA. This trend is
expected to continue, with MVFR cigs becoming prevalent at BPT/LCH
by 15-16Z. Further east and north, VFR should hang in there, at
least through mid afternoon at AEX and through the evening at
LFT/ARA. A band of SHRA/TSRA north of AEX could provide some
short-lived effects at this terminal over the next couple of
hours, but today`s convection will be increasing from SW to NE
through the day. This will produce periods of MVFR to IFR
cigs/vsbys during the afternoon and evening before activity
diminishes by 03-04Z tonight, with cigs lowering to IFR
thereafter. Winds will be E-SE today, strengthening to 10-15 KT
with gusts between 20-25 KT this afternoon.

24

&&

.MARINE...
Issued at 436 AM CDT Sun May 12 2024

Moderate to strong east to southeast winds will become more
southerly tonight, with winds gradually diminishing Monday
morning. Exercise caution headlines have been inserted for the
coastal waters for today and tonight due to the elevated winds and
increased seas.

Shower and thunderstorm chances will also increase through
tonight, with the highest chances expected Monday into Monday
night ahead of a cold front. A few strong storms will be possible
Monday afternoon into Monday night. Winds will shift westerly on
Tuesday, then offshore Tuesday night with the passage of the
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  78  66  85  65 /  80  80  60  40
LCH  82  72  84  70 /  70  40  60  50
LFT  84  74  86  73 /  60  60  60  60
BPT  82  74  86  70 /  70  30  60  40

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...Flood Watch through Tuesday morning for LAZ027-030.

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

GM...None.
&&

$$

SHORT TERM...24
LONG TERM....27
AVIATION...24