Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 211211
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
611 AM CST Tue Feb 21 2017

.AVIATION...
For the 21/12z TAFs, a large area of rain persists across portions
of Southeast Oklahoma, extreme Northeast Texas, and much of
Southern Arkansas and Northern Louisiana north of Interstate 20.
In addition, a few scattered thunderstorms have developed across
Deep East Texas east of LFK. Showers and isolated thunderstorms
will likely persist for much of the period as an upper trough
slowly moves across the region. Most of the precip should finally
exit the area by midnight. Ceilings will be variable through late
morning, ranging from MVFR to LIFR at the start of the period. A
slow improvement in ceilings is expected. KSHV, KTYR, KGGG, and
KLFK should lift in the VFR range by late this afternoon, but
flight conditions are expected to deteriorate overnight and more
low clouds and patchy fog develop.

CN

&&

.PREV DISCUSSION... /issued 504 AM CST Tue Feb 21 2017/

DISCUSSION...
The morning water vapor imagery depicts that the elongated upper
trough extending S from MO into Wrn AR to along the TX/LA line has
begun to close off over extreme Ern TX, with drier air aloft
continuing to entrain E into Ern LA. However, the mosaic radar imagery
depicts a large area of -RA development over extreme SE OK across much
of SW AR and across Ncntrl LA, primarily associated with the H700 low
that continues to drift S into Srn AR. The wrap-around stratocu around
the H850-700 low has filled in across much of E TX and has resulted in
considerable improvement to vsbys across this region. Meanwhile, with
the areas of -RA over SE OK/SW AR/NW LA, not expecting dense FG
development over these areas thus have cancelled the Dense FG Adv. for
the Wrn half of the area. Did word patchy dense FG over the Wrn
sections of E TX, as vsbys have been fluctuating over portions of
Wood, Smith, and Cherokee Counties.

The short term progs remain in good agreement with additional -SHRA
redevelopment near the H700 low today over SW AR/N LA, thus have re-
added high chance/likely pops today for these areas. Given the
extensive wrap-around low clouds and -SHRA, temps should not warm much
today and thus have lowered them another 3-5 degrees over SW AR/N LA.
Should see some warming occur by afternoon over SE OK/portions of E TX
as some of the cigs may scatter out, with these cigs possibly filling
back in over portions of these areas as the parent upper low continues
to drop SSE into SE LA/Srn MS. Should see low stratus development
occur late over SW AR/N LA, as drier air aloft continues to entrain S
in wake of the departing low. Did keep low chance pops going this
evening over Scntrl AR/Ncntrl LA tapered by slight chance pops farther
W to the AR/LA line, with any isolated -SHRA rapidly diminishing by
06Z Wednesday given the dry air intrusion aloft.

The morning low stratus Wednesday should lift/mix out by afternoon,
with a pronounced warming trend commencing with much above normal
temps expected. The cloud cover may linger a bit longer though over
Scntrl AR/Ncntrl LA resulting in slightly cooler temps. A SSW low
level flow will return Wednesday night and become enhanced Thursday,
with temps climbing back into the 80s over much of the area, and just
below record max territory. However, the progs continue to depict the
next shortwave that will traverse the Rockies Thursday out into the
Cntrl Plains/Midwest Thursday night, with a secondary shortwave
amplifying beneath the initial Midwest wave which will progress E into
the Mid MS Valley Friday. This will usher in a cold front into the
region Friday, before eventually clearing the Lower Toledo Bend area
and Ncntrl LA Friday evening. Moisture still looks to remain quite
shallow ahead of the front, thus have maintained a dry forecast with
the fropa. Still looking to see a return to seasonal temps Friday
night through this weekend, before a warming trend commences Sunday
and especially early next week.

The GFS/ECMWF are in good agreement but completely different from
solutions 24 hrs ago, establishing a SW flow aloft over the Srn
Plains/Lower MS VAlley early next week well ahead of the next upper
trough progged to develop along the CA coast. Strong low level
moisture advection and the potential for ripples in the flow aloft may
yield isolated convection through the end of the extended, thus have
reduced pops down to slight chance for now until more discernible
shortwaves embedded in the flow aloft can be found to focus more in
the way of sct convection.

Prelims to follow below...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  68  55  76  54 /  50  20   0   0
MLU  66  54  73  53 /  60  30  10   0
DEQ  68  48  77  50 /  60  10   0   0
TXK  66  52  76  54 /  60  20   0   0
ELD  63  53  73  50 /  70  30  10   0
TYR  72  51  78  55 /  10  10   0   0
GGG  70  52  77  54 /  20  10   0   0
LFK  71  53  79  54 /  20  10   0   0

&&

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

$$

15/09



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