Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 211613
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
1113 AM CDT Sat Oct 21 2017

.DISCUSSION...
Morning sounding moisture profiles, confined to low lvls, too
shallow for much in way of thunder, but do still suggest scattered
showers for se half of cwa, where a few isold showers were movg
nwd across northcentral LA. Vertical wind shear in place, so stg
convection still possible with enough capping modification above
the moist layer. Low clouds slow to lift, which will also limit
destabilization. Have lowered pops to 20 percent for nw half and
30 percent for se half, and 40 percent extreme se corner of cwa.
These clouds will also inhibit rising temps, but if the clouds
lift may need to send another update to raise daytime highs from
near 80 north to mid 80s south./07/

&&

.PREV DISCUSSION... /issued 717 AM CDT Sat Oct 21 2017/

AVIATION...
IFR/low MVFR cigs have developed early this morning across much of
the region, and will likely persist through much of the morning
before a slow improvement commences late this morning through the
early afternoon hours. Believe the lower cigs will persist until
20-22Z across SE OK/much of SW AR, with cig improvement expected
to gradually spread from S to N during the day. Very isolated
-SHRA have developed over portions of extreme Ern TX/SW AR/N LA
this morning, which should persist today, with more organized sct
convection possible this afternoon over Cntrl and the Ern
sections of Ncntrl LA, possibly affecting the MLU terminal. Have only
tempoed mention of VCTS for MLU only, although amendments may be
necessary for the other terminals should the more isolated -SHRA
result in lower cigs/reduced vsbys. Much of this convection should
diminish by early evening, but MVFR cigs should quickly redevelop
after 04Z Sunday over lower E TX/Ncntrl LA, and quickly spread N
across the remainder of the region through 06Z. A complex of strong
to svr convection is expected to develop later this evening over
Cntrl OK, which will quickly spread ESE into the region after 06Z
just ahead of a cold front. Have added VCTS mention in late tonight
for the TYR/GGG/TXK/SHV terminals, with gusty winds/reduced vsbys/
IFR cigs possible in the stronger storms. SSE winds 7-12kts, with
occasional higher gusts up to 18kts possible, mainly over the Wrn
sections of E TX. These winds may diminish briefly around 00Z Sunday,
but increase again later this evening/overnight ahead of the
line of convection and associated cold front. /15/

PREV DISCUSSION... /issued 453 AM CDT Sat Oct 21 2017/

DISCUSSION...
Satellite imagery reveals low clouds quickly advecting northward
this morning as dew points surge into the mid-upper 60s with more
room yet to climb later today as Gulf moisture continues pushing
northward. Meanwhile, water vapor imagery well depicts the upper
trough pivoting out of the Rockies and beginning to eject across
the Plains. This will set the stage for our very active weather
period, which will begin to ramp up later tonight as the trough
swings out farther east into the southern Plains and MS Valley.
In the meantime, expect widely scattered convection to develop
later today as temperatures climb toward the lower to mid 80s at
most locations. Southeast winds will also be rather breezy as a
surface low developing lee of the Rockies along the approaching
cold front will allow for a tightening pressure gradient across
our region.

As we approach midnight later this evening, the cold front will
be entering eastern Oklahoma and north central Texas with a solid
line of convection developing along and just ahead of the front.
This will quickly evolve into a squall line as the front begins to
encounter warmer and more unstable air ahead of it, generally east
of the I-35 corridor. The line of storms will accelerate eastward
into our northwest zones during the wee hours of the morning with
the threat of damaging winds being our primary concern. SPC Day 1
outlook continues to place our far northwest counties in a slight
risk for this threat after midnight through early Sunday morning.
A marginal risk covers the remainder of our northwest half as the
line of convection will enter a less favorable air mass with more
southeastward progression through mid to late Sunday morning. The
threats of large hail and isolated tornadoes remain very minimal
at this time but will certainly be monitored closely as this event
unfolds later tonight through early Sunday. The projected rainfall
amounts have remained fairly consistent with 1-2 inches on average
for much of the area with locally heavier amounts along and north
of I-30 where closer to 3 inches may occur in some isolated spots.

The cold front will gradually clear the region Sunday night as an
upper low closes off in the base of the upper trough. This may
slow the exit of convection across our eastern zones during Sunday
evening, but do expect all showers and storms to clear the region
by daybreak on Monday morning. A cooler and drier forecast will
prevail in the wake of the front with a second shot of cooler air
being ushered in by late Tuesday with a dry Canadian cold front.
However, return southerly flow coming back Wednesday evening will
quickly allow temperatures to warm back up by Thursday with high
temperatures approaching 80 degrees once again. This will allow
for some moisture return leading up to our next cold front set to
arrive by late Friday or on Saturday, depending on which forecast
model you believe. Either way, it appears next weekend could be a
repeat performance with showers and thunderstorms returning to the
region once again as we prepare to close out the month of October.

/19/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  83  69  74  54 /  20  70  90  10
MLU  85  69  77  56 /  30  50  90  30
DEQ  79  63  71  47 /  20 100  60  10
TXK  79  65  71  51 /  20  90  70  10
ELD  81  68  72  51 /  30  70  90  20
TYR  83  64  72  50 /  20  80  70  10
GGG  83  66  73  50 /  20  70  80  10
LFK  83  70  77  51 /  30  50  90  10

&&

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

$$



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