575
FXUS64 KLCH 140939
AFDLCH

Area Forecast Discussion
National Weather Service Lake Charles LA
439 AM CDT Sun Jul 14 2024

...New SYNOPSIS, SHORT TERM, LONG TERM, MARINE...

.SYNOPSIS...
Issued at 347 AM CDT Sun Jul 14 2024

Conditions have been mostly quiet early this morning, although a
few isolated showers and storms have started developing near the
SE TX and SW LA coast. Otherwise, very warm and muggy conditions
prevail as is typical of mid-July nights along the Gulf coast.
Temperatures this morning are mostly in the middle to upper 70s,
with low to mid 80s along the coast. Dewpoints were near or just a
few degrees lower than air temps, with relative humidity values
above 85 percent. A weak pressure gradient is in place as high
pressure ridges along the northern Gulf, and this is resulting in
calm to very light winds. Recent WV imagery and UA analysis shows
a narrow ribbon of moisture streaming across the southeastern half
of TX into the lower MS Valley, within a weak shear axis aloft
between high pressure centered over the Four Corners and ridging
from the western Atlantic into the E Gulf.

24

&&

.SHORT TERM...
(Today through Tuesday night)
Issued at 347 AM CDT Sun Jul 14 2024

The weakness aloft will move little today, and its proximity to
the area will support another day of mainly scattered convection
across the region. With high pressure noted from the surface to
roughly 700 MB, the main low level focus for convection will be
sea and bay breezes along with any residual boundaries from
showers and storms. Moisture and instability remain adequate for
storms to produce heavy downpours along with brief gusty winds.
Additionally, light and variable wind profiles will again
support the potential for short-lived tropical funnels. Convection
should wind down around sunset with the loss of daytime heating.

Temperatures today will be dependent on convective distribution
and timing, but highs should generally remain close to mid-July
normals in the lower to middle 90s. Light winds will trend more
southerly into the afternoon and this will maintain an influx of
moist air, with dewpoints expected to stay in the middle to upper
70s through the day. The combination of these elevated dewpoints
and very warm temperatures will again yield apparent temperatures
between 100 and 108 degrees. At this time, max apparent temps
look to stay just below advisory criteria, or at best may reach
criteria very briefly in a few isolated spots. Thus, no Heat
Advisory has been issued for today.

For Monday and Tuesday, minimal changes are expected in the
pattern aloft. Various impulses are progged to meander within the
shear zone, and the operational NAM continues to suggest the
possibility of a weak cutoff low evolving within this scenario
over NE TX/N LA while other guidance members just keep a weak
trough in place. Meanwhile, slightly drier midlevel air will
spread into the region and this will ultimately help to limit
overall convective coverage somewhat each afternoon, with the
highest PoPs (40%-50%) confined to the Acadiana region.

With convective coverage forecast to decrease on Monday and
Tuesday, daytime temps are expected to nudge upward slightly, with
highs reaching the middle to upper 90s across portions of central
LA. Daytime mixing should bring the aforementioned slightly drier
air to the surface, helping to lower dewpoints a few degrees
during the day and potentially mitigating the need for a Heat
Advisory. That said, an Advisory may be needed for the usual more
humid locations along the Atchafalaya Basin, and this will be
addressed in future forecast packages.

24

&&

.LONG TERM...
(Wednesday through Sunday)
Issued at 347 AM CDT Sun Jul 14 2024

Signals amongst the latest guidance suites continue to indicate
increased chances for precipitation across SETX and SWLA starting
during the upcoming mid week trending into the following weekend. A
very broad upper level trough extending over the Ozarks will
consolidate over the ARKLATEX region by Wednesday and gradually
deepen through Friday before merging with an upstream trough which
amplifies toward the Lower Mississippi Valley by Saturday.

Locally, temperatures are still projected to remain seasonably warm
across SETX and SWLA with heat indices exceeding 100F while actual
diurnal temperatures climb into low to mid 90s for highs for many
locations through Thursday. With primarily southerly onshore flow,
weak perturbations aloft are liable to set off isolated to scattered
showers/storms along the southern / coastal counties and parishes.
Further north an upper level trough over the Great Lakes region
shifts over eastern Canada with the SWrn portions of the troughing
extending down to the Ozarks. Meanwhile, our local upper level low
shifts SE of the Mississippi Delta while continuing to deepen. Thus
a combination of a frontal boundary developing southward over the
mid-south associated with the northern stream trough and the now
coastal upper level low provide very favorable conditions to
generate scattered showers / storms across the area continuing
through Thursday night.

Moving into Friday residual troughing left over the plains from the
exiting northern stream trough will begin to deepen further south
over Mississippi Valley. Model guidance still contains some variance
among timing and strength of the front, however, taking a national
blended approach illustrates some higher confidence the boundary
will shift toward the Gulf Coast by Friday afternoon. Hereafter, the
pattern becomes a little more unsettled with developing rounds of
precipitation across the area while the front slows along the Gulf
Coast. To the north, behind the front, modest high pressure rests
over the Midwest creating a notable boundary between relatively dry
/ cool continental air in that region and warm / humid subtropical
air to the south over the Gulf Coast. With the increasing chances of
precipitation and the approaching frontal boundary, temperatures are
forecast to trend slightly cooler to the upper 80s for many
locations over SETX and SWLA beginning Friday lasting into the
weekend.

Kowalski / 30

&&

.AVIATION...
(06Z TAFS)
Issued at 1213 AM CDT Sun Jul 14 2024

VFR and VRB to persist over a majority of the forecast period
with showers and storms ramping up in the late morning to
afternoon hours then ending in the evening.
Stigger/87

&&

.MARINE...
Issued at 347 AM CDT Sun Jul 14 2024

Surface high pressure ridging along the northern Gulf coast will
keep a light and variable to onshore flow and low seas over the
coastal waters for the next several days. Isolated to scattered
showers and storms will be possible, mainly from late night into
early afternoon. Locally higher waves/winds may occur with any
stronger storms.

24

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX  93  73  95  74 /  40  10  30   0
LCH  91  77  92  78 /  50  10  30   0
LFT  94  77  94  78 /  50  10  50   0
BPT  91  76  92  76 /  50  10  20   0

&&

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

$$

SHORT TERM...24
LONG TERM....30
AVIATION...87