211
FXUS64 KLCH 151118
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
618 AM CDT Tue Sep 15 2026

...New AVIATION...

.KEY MESSAGES...

- High pressure centered over the northern Gulf Coast will limit
  daily thunderstorm potential (20-30%) this week.

- Drier air will move into the region Thursday and Friday, which
  will lower heat indices and make conditions feel more
  comfortable.

- Precipitation chances increase Sunday into early next week as an
  area of low pressure moves into the northeastern Gulf.

&&

.DISCUSSION...
(Today through Monday)
Issued at 1240 AM CDT Tue Sep 15 2026

Evening upper air analysis and water vapor satellite imagery depict
a mid-level ridge centered over the lower Mississippi Valley, with
our CWA on the southwestern fringes of this ridge. Meanwhile at the
surface, high pressure centered over southeastern Louisiana is
resulting in light southerly flow across the area. A few patches of
light fog/mist are possible overnight over the CWA as skies clear,
particularly for any areas that received rain today. Any fog will
dissipate quickly with sunrise.

The upper ridge is projected to build and expand across the Deep
South Tuesday, with 500 mb heights nearing 99th percentile values
for mid-September. Tropical moisture will remain present underneath
the ridge, however, with PWAT in the 1.9-2.0 inch range (near 70th
percentile). With SBCAPE projected to be in the 2000-2500 J/kg
range, isolated convection is expected to develop in the afternoon.
Pulse storms that mature and dissipate rapidly will remain the norm
with deep layer shear virtually nonexistent. However, there may be
some isolated wet microburst potential with any stronger updraft
that does manage to develop, given modeled DCAPE in excess of 1200
J/kg and steep low-level lapse rates greater than 8.0 C/km. Outside
of convection, high temperatures will be in the mid 90s, with heat
indices in the 103-107 range. This is below heat advisory criteria,
but heat safety precautions are urged nonetheless.

For Wednesday, though the upper-level ridge will remain firmly in
place and continue to build over the upper South, guidance has
been acrossconsistent in depicting a weak inverted shortwave
trough tracking east to west across the CWA during the day. While
the extra forcing from this feature could provide somewhat of a
boost to convection, this will be tempered by a decrease in
instability as the mid-levels warm with the building ridge. HREF
mean SBCAPE is only in the 1000-1500 J/kg range, compared to
2000-3000 J/kg on previous days. Thus, expect another day with
isolated afternoon showers and a few thunderstorms, more likely
closer to the coast and farther from the influence of the ridge.

As the disturbance exits to the west, the upper-level ridge is
expected to shift westward and elongate along an axis from central
Texas into the mid-Mississippi Valley. This will set up a deep layer
northeasterly to easterly flow that will advect much drier air
originating from the Appalachian region into our CWA for Thursday
and Friday. LREF mean PWAT falls to 1.1-1.2 inches across the region
during this period (25th percentile relative to climatology), with
some ensemble members even decreasing this below 1 inch. Most
guidance has surface dewpoints dropping into the 60s with
afternoon mixing for all but immediate coastal regions, with
dewpoints in central Louisiana perhaps even falling into the 50s.
This dry air will result in rain chances near zero across the CWA.
While actual afternoon high temperatures will stay essentially
unchanged in the 90s, the heat index will be significantly more
tolerable with these lower dewpoints. The drier air will also
allow overnight lows to cool to values not seen in some areas
since early June, particularly along the I-49 corridor. NBM
probabilities of temperatures below 70 degrees approach or exceed
50 percent in this area.

Deterministic and ensemble guidance is in agreement in moving a
rather strong upper-level low across Florida and into the northern
Gulf over the weekend, where it is expected to stall into early
next week. This will come with a push of moisture as PWATs rise
back to the 1.7-1.8 inch range. As a result, a gradual increase in
rain chances is expected across the area for Sunday into early
next week, particularly for lower Acadiana. Afternoon highs will
decrease a few degrees heading into next week owing to the height
falls and increased cloud cover and rain chances, while overnight
lows tick up a couple of degrees.

64/Silas

&&

.AVIATION...
(12Z TAFS)
Issued at 614 AM CDT Tue Sep 15 2026

With light winds, clear skies and high humidity, a few patches of
shallow fog will be possible at terminals until shortly after
sunset or 15/13z with brief MVFR conditions.

Otherwise, as some drier air aloft builds in, chance for shower
activity will be limited today and therefore will not place any
convection for the terminals. Therefore, expect mainly VFR
conditions.

07/Rua

&&

.MARINE...
Issued at 1240 AM CDT Tue Sep 15 2026

High pressure over the northern Gulf will keep winds out of the
south to southeast at 4-10 kt through Tuesday night, with seas 1-2
feet. A disturbance moving through the area Wednesday will
strengthen easterly winds to 20-25 kt and increase wave heights to
near 8 feet. Small craft advisories will likely become necessary for
the Wednesday into Thursday time period.

&&

.FIRE WEATHER...
Issued at 1240 AM CDT Tue Sep 15 2026

A moist airmass remains in place over the region with winds
generally light out of the south to southeast. Most of the area
will remain dry through Wednesday, though an isolated afternoon
shower or thunderstorm cannot be ruled out. Afternoon MinRH will
be 40-50 percent inland and 50-60 percent near the coast. For
Thursday into the start of the weekend, much drier air will begin
to move into the CWA, with afternoon MinRH decreasing to 30-40
percent inland and 40-50 percent near the coast. East winds
around 5-10 kt are expected for this period.

&&

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

$$

PUBLIC/FIRE/MARINE...64
AVIATION...07