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000
FXUS64 KLCH 181428
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
928 AM CDT Thu Apr 18 2024

...New UPDATE...

.UPDATE...
Issued at 923 AM CDT Thu Apr 18 2024

Short wave moving across in the fast west-southwest flow aloft
over-performing some and allowing elevated showers to get going.
Therefore, have updated the forecast to increase pops for this
morning into early afternoon. Activity should decrease and move
off to the west during the afternoon hours. Despite the cap seen
on the 18/12z upper air sounding, enough elevated CAPE and
favorable mid level lapse rates to get some thunder and lightning
with the showers so will also add thunder to the weather grid with
the increase in pops.

Otherwise, remainder of the forecast is on track.

Rua

&&

.SHORT TERM...
(Today through Saturday night)
Issued at 330 AM CDT Thu Apr 18 2024

A broad regime of surface high pressure extends west across Florida
into the central Gulf of Mexico. Southerly flow accompanies this
pattern locally facilitating warm, humid, and primarily cloudy
conditions. Low pressure troughing over Texas has created a weak
gradient across SETX / SWLA, to generate SSE breezes with gusts near
20 mph again. A well defined 700-800mb ridge aloft caps off any
potential convection with very noticeable inversion / dewpoint
depression during recent upper air soundings. Mid to upper level air
moisture profiles are fairly humid which has resulted in some light
elevated precip / virga over the northern tier portions of the CWA
trending across NETX into north central LA. POPs have been minimized
given this dry layer aloft and low level subsidence through the
start of the weekend. Temperatures under this southerly regime in
the meanwhile will continue to climb toward the mid 80’s for many
locations.

The focus continues to be throughout the weekend which trends into
the early long rage. In the meanwhile, Saturday, a cold front will
begin to slow and modify as downstream low pressure detaches from
this pattern over the Southern Plains. While the strongest
divergence remains over the Northeast where the longwave trough
pattern slowly migrates into the NW Atlantic, a relatively small
shortwave deepens across NWTX which creates better dynamics in the
low levels. The result is a weak surface trough along the advancing
frontal pattern. POPs increase along with chances of thunder
throughout the late afternoon and overnight into Sunday where the
front, driven by a building ridge over the central Plains, moves
offshore. At this time, no modes of severe weather are elevated. The
national blend of models has been more consistent in keeping event
totals closer toward 0.50” - 0.75.” Worth noting the potential for
excessive rainfall is possible, but not highly favored ahead of the
frontal boundary Saturday evening through Sunday. Northern portions
of the CWA there stands a marginal risk for excessive rainfall.
Together with probabilistic guidance, northern tier counties and
parishes stand the better chances – albeit still bordering marginal—
for any excessive rainfall. Reduced diurnal highs and brief
northerly flow will take place as the front clears into the Gulf
Sunday.

Kowalski/30

&&

.LONG TERM...
(Sunday through Thursday)
Issued at 330 AM CDT Thu Apr 18 2024

As Sunday gets underway, the cold front will be situated near the
coast or just offshore. A cooler airmass will settling into the area
as high pressure builds south across the plains. Meanwhile,
widespread showers and a few storms are expected to be ongoing
during the morning as a midlevel southern stream shortwave crosses
the region. Instability and shear are expected to be rather meager
so no severe weather is expected, and any thunder will likely be
limited. Moisture, however, will be prolific with PWATs peaking near
1.8 inches (near the max value for mid April per SPC climatology).
This will be sufficient for some heavier showers and high rainfall
rates, which could pose a localized flash flood risk in urban and
low lying areas, primarily over our eastern zones where the highest
rain chances are expected to be through early afternoon. Overall,
rainfall totals are generally expected to be between one half to one
inch, but locally higher amounts will be possible where heavier
showers occur.

Convection should diminish from west to east during the afternoon as
dry northwesterly flow develops in the wake of the shortwave.
Lingering cloud cover combined with cold air advection on gusty
northerly winds will make for rather cool conditions on Sunday, and
daytime highs will likely struggle to reach 70 degrees north of the
Highway 190 corridor.

As surface high pressure settles across AR Sunday night, winds will
diminish across the region. Temperatures Sunday night into Monday
morning are expected to be the chilliest of the forecast period,
with lows falling to around 50 degrees across the northern zones
(upper 40s will be possible across central LA), with lower 50s
across the southern half of the area. Cloud cover will decrease
during the day Monday, with rather pleasant and seasonable
conditions expected.

A warming trend will develop going into the midweek period as the
surface high slides east and low pressure forms over the southern
plains. Flow aloft will trend more zonal, with intermittent weak
disturbances expected to bring some low rain chances back into the
area by Tuesday. Some differences begin to arise in the global
models beyond this time, but there is a general consensus toward
improving rain chances for Wednesday and Thursday (Days 7-8). NBM
PoPs remain on the drier end of the spectrum but will likely be
evolving over the coming days.

24

&&

.AVIATION...
(06Z TAFS)
Issued at 330 AM CDT Thu Apr 18 2024

OVC ceiling have generally lowered under 2500ft with some FEW to
BKN areas between 500-1000ft. Visibilities will continue to
reduce through up to sunrise with MVFR vis expected during the
dawn hours. Patchy FG / BR forecast given ample warm onshore flow
over cooler surfaces. However, breezes aloft have continued
prevent dense fog from setting in and are expected to further
these breezes through the remainder of the nocturnal and early
diurnal hours. Both Vis and Ceilings will increase shortly after
sunrise, allowing any brief IFR conditions to improve toward MVFR
by mid morning. Continuing through the remainder of the day,
warm/humid conditions will likely trend ceilings MVFR with some
VFR improvements possible afternoon briefly.

&&

.MARINE...
Issued at 324 PM CDT Wed Apr 17 2024

A similar pattern through the end of the week with a surface high
off the Florida Atlantic coast ridging into the coastal waters
with lower pressure across the Southern Plains. This will result
in light to occasionally modest southerly winds into the beginning
of the weekend.

A surface front will enter the region over the weekend with an
increase in shower activity.

This front will move across the coastal waters late Saturday night
into Sunday morning with winds becoming offshore that will persist
into early next week.

Rua

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  85  66  86  65 /  20   0  10  10
LCH  82  70  84  69 /  10   0   0   0
LFT  85  71  87  69 /  20   0   0   0
BPT  84  70  86  69 /  10   0   0   0

&&

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

$$

SHORT TERM...30
LONG TERM....24
AVIATION...30