Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 232100
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
400 PM CDT Sun Apr 23 2017

.DISCUSSION...
The stratocu field still continues to hang tough this afternoon
especially over N LA, but drier air spilling S in wake of the
departing shortwave associated with the closed low over Middle
TN/Nrn AL should result in these cigs clearing across this area
early this evening, resulting in a clear sky for the remainder of
the overnight hours. Meanwhile, sfc ridging continues to build SSE
across the Srn Plains this afternoon, and will be centered over
the region overnight. This will result in nearly ideal radiational
cooling overnight, resulting in very pleasant and cool conditions,
with min temps still several degrees above record lows for the
date. However, a warmup will quickly commence shortly after
daybreak Monday as low amplitude ridging aloft builds over the
area, and the sfc ridge beginning to drift E out of the area by
afternoon. Srly winds will gradually return across E TX/SE OK/Wrn
Ar and Wrn LA Monday but remain light, although RH`s will continue
to be pleasant as they bottom out around 30%. Thin cirrus should
also increase from the W especially by afternoon, although max
temps will be unaffected as they top out slightly above seasonal
norms.

The weak ridging Monday will quickly flatten out Tuesday in
response to broad troughing aloft underway from the Four Corners
Region E into the Srn Rockies. This will induce sfc cyclogenesis
over the TX/OK Panhandles and Srn KS Tuesday morning, with the
pressure gradient tightening across the Srn Plains. A portions of
the 30-40kt SSW low level flow should also mix down Tuesday as
well, resulting in windy conditions for the Wrn half of the
region. Low level moisture advection will also be underway, with
the potential for a cu field returning to all but Scntrl AR and
the Ern sections of Ncntrl LA. A 45-50+ Swrly LLJ should develop
Tuesday night as the aforementioned troughing aloft amplifies a
bit farther S into the TX S Plains and Middle Red River Valley,
with enough moisture and forcing ahead of the trough warranting
the continued mention of slight chance pops late Tuesday night
across the NW sections of NE TX into SE OK/adjacent SW AR.
However, the short term progs continue to suggest a deeper and
more Srn trough track across OK and N TX Wednesday, as sufficient
deepening of the low level moisture is met during peak heating of
the afternoon. The presence of upper 60s/near 70 dewpoints and
diurnal heating will yield moderate MLCapes of 2000-3000 J/Kg
Wednesday afternoon over the Wrn half of the region along and
ahead of the attendant cold front, with sufficient H700-500 lapse
rates increasing buoyancy to yield deepening convection, some of
which may become severe, especially over E TX/N LA/SW AR for the
afternoon. This convection should diminish from W to E Wednesday
evening with the fropa, with a brief return to slightly cooler but
drier air settling into the region late Wednesday night/Thursday.

There is better agreement amongst the GFS/ECMWF with the
aforementioned cold front settling S somewhere across the NW Gulf
and Srn LA coast Thursday morning, before this front begins to
return back N as a warm front Thursday afternoon/night. The 12Z
ECWMF continues to depict a similar solution to its 00Z
predecessor with elevated convection developing along the Red
River Valley of Srn OK/N TX Thursday afternoon with the passage of
weak shortwave energy, while expanding E into SW AR during the
evening. This solution would halt the Nwd expansion of the warm
front Thursday evening, with the rain cooled air halting the warm
front in VC of the I-20 corridor. Not quite buying this scenario
given the significant amount of dry air this shortwave would have
to overcome to generate convection, thus have tailored the
Thursday/Friday forecast closer to the GFS/Canadian blends, with
suggest dry conditions will continue Thursday, with the warm/moist
sector expanding back N across much of the region Thursday night.
As this warm front interacts with the weak shortwave energy in VC
of the I-30 corridor late Thursday night, isolated to widely sct
convection may develop, with the threat for isolated strong storms
not completely ruled out given the steep lapse rates aloft. The
warm front should continue to lift N out of the area Friday, with
convection remaining isolated for the most part except for the Nrn
zones which will remain under the influence of ripples in the
increasingly SW flow aloft ahead of the deepening closed low
across the Great Basin and Desert SW.

Both the GFS and ECMWF continue to delay the Ewd advance of this
system for next weekend, with better consistency in depicting the
closed low lifting NE into the Plains with a trailing longwave
trough swinging E across the Srn Plains Sunday. Strong wind shear
and increasing instability out ahead of this system will yield the
threat for an organized severe weather episode as convection
increase and eventually organizes into a potential squall line as
it progresses E across the area Sunday and Sunday night
along/ahead of the next attendant cold front.

Prelims to follow below...

15

&&

.PREV DISCUSSION... /issued 133 PM CDT Sun Apr 23 2017/

AVIATION...
For the ArkLaTex, VFR with decks lifting and scattering over all
but KMLU where the back edge is an hr or two out. Sfc winds are
still seeing some teen gusts from North and some variability in
direction NW-NE with SKC mixing. Aloft, we are N/NW 10-30KT for
climb out and then back to West with a max of 80KT on our 6 a.m.
balloon sounding at FL220. SKC High pressure over N TX will weaken
and move E of the MS river and return flow off the Gulf setting
us up for more convection by midweek w/ 27/00z fropa. /24/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  46  81  55  87 /   0   0   0   0
MLU  47  78  50  83 /   0   0   0   0
DEQ  39  79  50  83 /   0   0   0   0
TXK  43  79  55  86 /   0   0   0   0
ELD  43  78  50  84 /   0   0   0   0
TYR  46  81  58  87 /   0   0   0   0
GGG  44  80  56  86 /   0   0   0   0
LFK  45  82  58  87 /   0   0   0   0

&&

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

$$

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