543
FXUS64 KSHV 180450
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
1150 PM CDT Tue Sep 17 2024

...New AVIATION...

.UPDATE...
Issued at 936 PM CDT Tue Sep 17 2024

Clear skies overhead tonight as mid-level ridging slides east
into the Four State Region. Overnight will trend quiet, but
humidity will remain as area dew points will sit in the upper 60`s
and low 70`s. Areawide patchy fog expected once again this
evening as the winds will generally sit below 5 mph. Aside from
adjusting hourlies to meet latest trends, no changes were needed
with the evening update.

KNAPP

&&

.SHORT TERM...
(This evening through Wednesday Night)
Issued at 209 PM CDT Tue Sep 17 2024

Around 18z this afternoon, the mid and upper levels of the
atmosphere feature a Rex Block over the Eastern US, with a ridge
of high pressure noted over the Great Lakes and low pressure
centered over the southern Appalachians. To the west of this lies
on elongated ridge from SW to NE across the Southern Plains into
the Northern MS Valley downstream of a strong longwave trough over
the Western US, with a closed low around the Great Basin. In the
lower levels, an expansive area of high pressure stretches across
the NE into Great Lakes and Midwest, while a sfc low sits over the
Carolinas and a stationary front sits near the northern Gulf
Coast.

Focusing closer to home, water vapor imagery shows a very subtle
shortwave trough/shear axis near the S LA and S MS border, with
showers developing in its vicinity. This disturbance is the
remnants of Francine, of which will continue to move SE through
tonight. Lift/deformation within the disturbance`s vicinity, along
with plentiful low level moisture characterized by dewpoints in
the low 70s will allow for the development of isolated showers
through the afternoon and early evening hours. The highest chance
(roughly 30%) for showers will be across eastern and southern
zones, with about a 15-20% chance of an isolated shower elsewhere.
Thunder chances will remain low but nonzero as MLCAPE values hang
around 250J/kg despite meager low level and mid level lapse rates
of less than 6 C/km. Shower activity will then wind down after
sunset with the loss of daytime heating and the continued E/SE
progress of the mid level disturbance.

On Wednesday, the longwave trough over the Western US will remain
active, with an area of closed low pressure deepening over the
Northern Rockies and another digging shortwave along the Central
CA Coast. The progression and deepening of this longwave trough
will then shift the elongated ridge axis eastward across the
ArkLaTex. This will make for rising temperatures back towards 90
for the region as subsidence aloft increases. Before the heat
returns, patchy fog will greet the area early Wednesday morning as
moisture remains plentiful near the surface underneath the ridge.

Fog will likely redevelop again overnight Wednesday into Thursday
as low level moisture remains trapped underneath the ridge under
clear skies and light winds.

Kovacik

&&

.LONG TERM...
(Thursday through next Monday)
Issued at 209 PM CDT Tue Sep 17 2024

At the start of the long term forecast period, the digging trough
over Central CA will continue to dig slowly S/SE towards S CA.
This will further amplify the ridge downstream across the Four
State Region and Southern Plains, allowing temperatures to
continue to rise back into low to mid 90s. Similar conditions can
be expected for Friday as the S CA closed low moves slowly E into
the desert SW.

For the weekend, WPC cluster solutions and most ensemble means
support the idea of the desert SW closed low beginning to lift
towards the Southern Rockies. This will begin to dampen the ridge
on its NW periphery, likely allowing for the advection of high
level clouds into northern zones. High pressure both aloft and at
the sfc will hold strong enough for the remainder of the area to
remain hot and dry, with highs again in the low to mid 90s with
dewpoints near 70.

Currently seeing decent agreement in the ensemble guidance Sunday
into next week with the low lifting into the Central Plains and
dampening the northern periphery of the ridge further. Based on
the current projected track of this system, would expect sfc
cyclogenesis in the lee of the Rockies to commence across the OK
panhandle or western KS, which will keep the brunt of the dynamics
and associated frontal boundary development to the north of the
Four State Region. That being said, there will remain some
discrepancy with this and it still appears possible a cold frontal
boundary could approach far northern zones at the end of the
forecast period, supporting at least low end rain chances. With
increasing cloud cover likely across most of the forecast area
from this system, high temperatures will likely cool a few degrees
into early next week.

Kovacik

&&

.AVIATION...
(06Z TAFS)
Issued at 1150 PM CDT Tue Sep 17 2024

Mostly a cloud free airspace ovhd attm and will prevail that
to begin the 06z TAF package. With light winds, may see some basin
fog spread out and impact a few terminals closer to sunrise and
some of this could become dense but will hold off on anything
other than MVFR reductions to VSBY with this package and address
anything more dense with the 12z TAF package. Otherwise, a weak cu
field will develop today but it should not be as expansive or
concentrated as what we have seen the last couple days. Thus,
beyond mid morning with any VSBY concerns, VFR conditions should
prevail through the day and into the evening hours tonight. Look
for mostly variable winds under 10kts today.

13

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  72  90  72  93 /   0   0   0   0
MLU  68  89  67  91 /  10  10   0   0
DEQ  66  89  66  92 /   0   0   0   0
TXK  69  90  70  94 /   0   0   0   0
ELD  65  88  65  92 /  10   0   0   0
TYR  71  93  73  95 /   0   0   0   0
GGG  70  91  71  94 /   0   0   0   0
LFK  72  92  72  94 /   0  10   0   0

&&

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

$$

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