228
FXUS64 KSHV 170507
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
1207 AM CDT Tue Sep 17 2024

...New AVIATION...

.UPDATE...
Issued at 936 PM CDT Mon Sep 16 2024

Mid-level energy left over from the decaying surface circulation
of Francine continues to spin across the LA/AR/MS border tonight,
and has influenced NW Louisiana and SW Arkansas with prevailing
showers through the evening. These have since started to
dissipate and with guidance pointing towards low clouds and some
patchy fog this evening, elected to include this within the
evening update. Meanwhile, through the overnight, the remnant mid-
level energy will become ingested within a broader upper low
feature across the Carolinas. This will take most of the night to
exit the region before it`s influence becomes no more. Aside from
adjusting hourlies to match the latest trends, and adding the
verbiage of patchy fog, the forecast remains on track.

KNAPP

&&

.SHORT TERM...
(This evening through Tuesday Night)
Issued at 126 PM CDT Mon Sep 16 2024

The synoptic scale pattern this afternoon is characterized by an
elongated area of low pressure extending from the Mid and Lower MS
Valley eastward to the Carolinas, of which contains the remnants
of Francine near the AR/MS border and potential tropical cyclone 8
near the NC/SC Coast. This area of low pressure is part of a Rex
Block across the Eastern US where high pressure resides above the
elongated low over the Great Lakes. A ridge of high pressure is
then noted across the Southern Plains in advance of a strong
longwave trough over the Western US, where closed low pressure
resides over Central CA. In the lower levels, high pressure
encompasses a large portion of the NE and Great Lakes region, with
closed low pressure associated with the tropical system along the
Carolina Coast and a weak sfc trough across the ArkLaMiss
associated with Francine remnants. A stationary boundary also
remains draped along the eastern slopes of the Rockies S/SE
towards and across the Northern Gulf Coast.

With the remnants of Francine lingering near the ArkLaTex, skies
have been mostly cloudy across most of the CWA. In addition,
enough large scale forcing in tandem with daytime heating and rich
low level moisture is allowing for the development of scattered
rain showers across northern, northeastern, and eastern portions
of the CWA. Expect this general area to have the highest rain
chances through mid-evening, however, a few light showers may
develop just about anywhere. Mid level lapse rates remain rather
meager at around 5-6C/km, however, given that the there appears to
be at least a weak center of mid level circulation clipping the
area, isolated thunderstorms cannot be ruled out. The biggest
impacts from today`s weather will be brief, heavy downpours. With
the loss of daytime heating after sunset and the continued
weakening of the system, scattered shower coverage will become
more isolated into the overnight period.

Provided the scattered rain showers from Monday, along with
continued abundant moisture in the low levels, clouds will be
quick to increase and lower overnight tonight into Tuesday
morning. Patchy fog is likely to develop, as well patchy areas of
light rain and/or drizzle. Conditions will be slow to improve
through the morning hours on Tuesday, but will eventually give
way to partly to mostly cloudy skies. With the remnants of
Francine expected to move back towards the LA Coast, a few rain
showers may advect into SE zones with the advance of the sea
breeze. Cannot rule out even an isolated shower as far north as
the Shreveport/Bossier area. This period of unsettled weather in
the short term forecast period will then begin to change heading
into the long term forecast period.

Kovacik

&&

.LONG TERM...
(Wednesday through next Sunday)
Issued at 126 PM CDT Mon Sep 16 2024

By Wednesday, Francine remnants will become absorbed by the east
to west moving tropical remnants from the Carolina Coast, making
for a larger scale area of low pressure east of the MS River.
Meanwhile, the pattern will become more progressive across the
Western US, helping to push the Southern Plains ridge into the
ArkLaTex. This will make for increasing high temperatures back
into the 90s and clearer skies.

Ensemble guidance/WPC cluster analysis is in good general
agreement on Thursday with an upper level ridge over the ArkLaTex
and two areas of low pressure to the north and west-one over the
Northern Plains and the other off the Central CA Coast. The
Central CA trough is expected to dig towards S CA, though there
remains some discrepancy towards the extent of the digging and
the exact location. But at this point in time, model guidance
favors enough digging to the SE to allow for the amplification of
the ridge downstream. This points to warmer temperatures on
Thursday in the low to mid 90s. This pattern looks to then linger
through at least the first half of the weekend as the low jaunts
across the desert SW.

The low over the desert SW will then begin to lift towards the
Central Rockies on Sunday, which is supported by most of the WPC
clusters in some fashion. This will help dampen the ridge on its
northern periphery. With lee cyclogenesis then expected to take
place east of the Rockies, a frontal boundary may then attempt to
approach far northern zones at the end of the forecast period.
The question will become where the closed mid level low lifts and
where subsequent sfc cyclogenesis takes place in regards to
when/if a late period fropa can be anticipated.

Kovacik

&&

.AVIATION...
(06Z TAFS)
Issued at 1204 AM CDT Tue Sep 17 2024

A mix of low VFR, MVFR and IFR ceilings currently across SW AR and
looking for those lowering of ceilings to continue into the
predawn hours across portions of NE TX and N LA as well. Also
concerned with VSBY restrictions across these locations and the
possibility of dense fog across our NE TX terminals towards
sunrise as well. Any VSBY restrictions and/or MVFR/IFR/LIFR
ceilings will gradually lift and/or scatter out by mid to late
morning with VFR conditions prevailing through the end of the TAF
period. While isolated convection will be possible today, coverage
does not warrant a mention with this TAF package. Look for winds
today from the NE to E generally under 10kts through the period.

13

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  86  71  91  73 /  20   0   0   0
MLU  85  67  89  68 /  20   0   0   0
DEQ  86  65  90  67 /  10   0   0   0
TXK  86  69  91  71 /  10   0   0   0
ELD  85  65  89  67 /  10   0   0   0
TYR  89  71  93  74 /  10   0   0   0
GGG  86  70  92  72 /  10   0   0   0
LFK  89  71  92  72 /  10   0  10   0

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&

$$

SHORT TERM...23
LONG TERM....23
AVIATION...13