Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 101219
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
619 AM CST Sat Dec 10 2016

.AVIATION...
For the ArkLaTex, VFR deck 5-6kft moving slowly E over terminals
this morning. Calm sfc winds are becoming light E/SE and will
increase in speed by late in the this cycle as an approaching
front tightens the pressure gradient. Clouds continue to increase
for tomorrow with rain showers into Monday. Climb winds today are
light and vary off the surface, becoming Westerly at cloud base
and into flight levels with 30KTS increasing to 60KTS by FL300.
/24/

&&

.PREV DISCUSSION... /issued 522 AM CST Sat Dec 10 2016/

DISCUSSION...
The morning 11-3.9u satellite imagery depicts an extensive area of cu
that continues to gradually build E across much of E TX and N LA
along and N of I-20...which has acted as a blanket and kept early
morning temps above freezing over these areas. Meanwhile...farther
S...temps have fallen off below freezing although some modification
in temps is expected by daybreak over portions of Deep E TX where
additional cu is rapidly building E. These will be the last freezing
temps expected through much of the forecast period as the arctic sfc
ridge in place from the MS Valley SW into E TX is expected to slide E
resulting in a SSE low level flow. Even with the return flow
today...temps will be slow to recover with the cloud cover expected to
persist...and possibly spread over more of the region. Additional cu
noted over Cntrl TX is expected rapidly build NNE into E TX this
afternoon...before these cigs rapidly spread E across the remainder of
the region this evening. In fact...a 40-50+ kt SWrly LLJ is expected
to develop this evening over Cntrl TX/OK in response to a tightening
pressure gradient...with this tightening pressure gradient expected to
slide E over the area Sunday. The deepening low level moisture and
winds will limit much of a temp fall this evening...with some temps
actually slowly warming overnight.

With the LLJ shifting E over the region Sunday...should start to see
some of these stronger winds mixing down despite the cloud cover in
place...resulting in gusty Srly winds from late morning through the
afternoon. This will result in a pronounced warming trend with temps
actually climbing back above seasonal norms over much of the region.
The deepening low level moisture may also result in isolated areas of
-RA/-DZ late tonight over the Wrn sections of E TX/SE OK...which will
gradually shift E over the remainder of the region Sunday. Have toned
down pops back to low chance as forcing will be weak/isentropic...and
QPF amounts very light before we await a shortwave that will develop
across the upper Red River Valley Sunday afternoon and traverse mainly
SE OK/SW AR Sunday night. The short term progs are in good agreement
with the best/deeper forcing remaining just NNE of the area...although
sct -SHRA should become more focused Sunday evening along/just ahead
of a weak cold front that will slowly dig into extreme SE OK/NE TX/Wrn
AR. Have maintained mid/high chance pops Sunday night for SW
AR/portions of Ncntrl LA...tapering pops back Monday as this shortwave
departs the area. The weak cold front itself remains progged to pull
up stationary Monday afternoon over portions of N LA/E TX...which
should lock the low stratus/stratocu in place for much of the region
but result in quite a range in max temps from N to S. This front
should eventually build back S Monday night in response to sfc pressure
rises ahead of a second cold front approaching the region from the NW.

Prefer the slower frontal movement of the ECMWF as the flow aloft
remains zonal across much of the Plains...with the post-frontal air
mass quite shallow and slowed due to the higher terrain of SE OK/Wrn
and Cntrl AR. Still can/t rule out isolated showers given the weak
overrunning atop this shallow air mass...but QPF amounts should remain
light. The cooler post-frontal air should gradually deepen across the
region Wednesday with Thursday the coldest day of the forecast
period...before the air mass begins to modify Friday through next
weekend as a return SSE low level flow returns. The flow aloft remains
progged to become SW by week/s end as longwave troughing develops over
the Intermountain W and begins to shift E over the Rockies. This
should result in sct -SHRA development increasing Friday through the
weekend...with the potential deeper convection development in the
increasing warm advection regime...and embedded shortwave energy ahead
of the approaching longwave. Above normal temps appear to continue
through the remainder of the extended as well.

Prelims to follow below...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  52  45  67  59 /   0  10  30  30
MLU  50  39  65  60 /   0   0  10  50
DEQ  47  40  61  47 /   0  20  30  40
TXK  47  42  64  53 /   0  10  30  40
ELD  48  40  62  56 /   0   0  20  50
TYR  52  47  70  53 /   0  20  30  20
GGG  51  45  70  57 /   0  10  30  20
LFK  54  46  72  61 /   0  10  30  30

&&

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

$$

24/15



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