Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 231150
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
550 AM CST Thu Feb 23 2017

.AVIATION...
For the 23/12z TAFs, patchy fog across Deep East Texas, the Toledo
Bend Country, and portions of North Central Louisiana has lead to
some instances of MVFR flight conditions, and even LIFR at times
at KMLU. However, the fog is expected to dissipate by mid
morning, and all sites should be in the VFR range by 23/15z.
Only some high clouds are expected for much of the day along and
north of Interstate 20. During the daytime, Southerly winds will
increase to between 10 and 15 kts with higher gusts between 20 and
25 kts, especially across East Texas. Wind speeds will diminish
slightly overnight, but will likely continue to be between 7 and
12 kts. The strong southerly flow is expected to bring low clouds,
patchy fog, and MVFR flight conditions along and south of
Interstate 20 during the overnight and early morning hours of
Friday.

CN

&&

.PREV DISCUSSION... /issued 527 AM CST Thu Feb 23 2017/

DISCUSSION...
Light SSE winds have returned to the region early this morning in
wake of the departure of the upper level low which has now shifted SE
into Srn FL, but am watching areas of advection FG develop/slowly
spread NNE into the lower Toledo Bend Country and into the Cntrl LA
attm. The HRRR has initialized well on the FG this morning, and depict
it advecting farther N into portions Ncntrl LA through mid morning
before slowly lifting. Vsbys across Cntrl LA now have fluctuated
the last couple of hours, and thus will hold off on a Dense FG Adv
for these areas and continue to monitor but have inserted patchy
dense FG wording into the forecast through mid morning.
Otherwise, the pressure gradient will tighten later this morning
across the Srn Plains ahead of sfc cyclogenesis over the OK
Panhandle and SW KS, resulting in strong srly winds enhancing the
low level warm and moisture advection N into the area from the Nrn
Gulf. Have posted a Lake Wind Advisory from 17-00Z today for
McCurtain County OK and the wrn sections of E TX, with wind gusts
up to 30 mph possible. With the increase in srly winds areawide,
max temps today will climb into the lower to mid 80s, near or just
shy of record max temp territory. Winds should stay up overnight
tonight, with areas of low stratus developing and rapidly
advecting N late especially over E TX/N LA. These winds and the
increasing stratus should keep min temps tonight from falling much
below 60 degrees over these aforementioned areas.

The morning water vapor imagery depicts a compact upper low over Srn
ID/NW UT this morning, which will traverse E across the Rockies today
before emerging out into the Cntrl Plains tonight. Secondary
shortwave energy will quickly translate ESE beneath this closed low
Friday and across OK/Nrn AR, which will usher a cold front SE across
the region. This front should be entering McCurtain County OK and
portions of extreme NE TX around/shortly after daybreak Friday before
quickly mixing SE into Scntrl AR/extreme NW LA/E TX by midday, before
exiting the region around/shortly after dusk. Despite the return of
low level moisture ahead of the front late tonight through Friday, the
deep lyr moisture profile still looks too shallow to support -SHRA
development, thus have maintained a dry forecast with the fropa.
However, the short term progs and MOS continue to suggest the cooling
will not immediately follow the fropa, with the potential for
compressional warming along/just ahead of the frontal zone
contributing to another afternoon of much above normal temps. However,
much drier air will filter ESE in wake of the fropa, contributing to
min RH`s falling to around or just below 25% across much of E TX/SE
OK/SW AR and possibly extreme NW LA. These low RH`s and WNW winds
10-15kts could result in an enhanced fire danger over portions of
these areas especially where much lighter rainfall amounts were
observed Tuesday over portions of SW AR/extreme Ern TX/NW LA given the
extent of drying that has/is expected to occur Wednesday and today.

Should finally see a return to near seasonable temps Friday night
through the weekend as Canadian sfc ridging builds SE into the Srn
Plains. The final weekend of the Mardi Gras parades look great under a
clear sky, with a nip in the air given the much lower dewpoints that
will advect into the region. Good radiational cooling Saturday night
should result in a light freeze over the more protected areas of SE
OK/portions of SW and Scntrl AR, before a gradual warmup commences
Sunday with the return of a SSE low level flow.

Quite a few changes were noted in the 00Z GFS/ECMWF this morning, with
strong low level moisture advection commencing Sunday with the flow
aloft gradually transitioning to SW late in the weekend. The progs
suggest that warm advection -SHRA may develop Sunday afternoon along
the I-30 corridor of NE TX/SW AR, before expanding a bit Sunday night
as a warm front lifts N through the area. Even aloft, these progs have
reverted back to an earlier solution from several days ago with an
embedded shortwave traversing NE across the Red River Valley of N
TX/Srn Ok into Ern OK/Wrn AR Sunday night helping to enhance
convection development especially along the I-30 corridor. Convection
development here should diminish Monday with the departure of this
shortwave, with the warm sector expanding N into OK/AR. Have
discounted the GFS solution from Monday and beyond as drastic changes
have been noted from earlier runs, with it suggesting a cold front
sweeping SE across the region Monday in wake of the departing
shortwave. Not buying this at all given the deep SWrly unidirectional
flow aloft. Much above normal temps look to persist through midweek
before the next progressive upper trough is expected to translate E
into the Plains/MS Valley Wednesday. This trough should usher another
cold front SE into the region Wednesday, with sct convection expected
along and ahead of the front. Still too far out to ascertain svr
potential with this next fropa/trough passage given the considerable
uncertainties beyond Monday, but the trend for cooler and drier air
for the late week timeframe still looks on track from previous model
runs.

Prelims to follow below...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  83  58  80  41 /   0  10  10   0
MLU  80  58  81  43 /   0  10  10  10
DEQ  81  53  72  32 /   0  10  10   0
TXK  81  57  75  36 /   0  10  10   0
ELD  80  56  77  36 /   0  10  10   0
TYR  84  57  75  40 /   0  10  10   0
GGG  83  57  77  40 /   0  10  10   0
LFK  84  60  82  42 /   0  10  10   0

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...Lake Wind Advisory from 11 AM this morning to 6 PM CST this
     evening for OKZ077.

TX...Lake Wind Advisory from 11 AM this morning to 6 PM CST this
     evening for TXZ096-108>111-124-125-136-137-149-150.

&&

$$

15/09



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