Area Forecast Discussion
Issued by NWS Shreveport, LA

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539
FXUS64 KSHV 201159 AAA
AFDSHV

Area Forecast Discussion...UPDATED
National Weather Service Shreveport LA
659 AM CDT Fri Oct 20 2017

.AVIATION...
VFR conditions will persist through much of the 12Z TAF period,
although extensive areas of AC and cirrus will continue to
overspread the region along and ahead of a shortwave trough over
Ecntrl TX that will slowly eject NE across the region today. This
will result in sct areas of -SHRA affecting portions of E TX/SE OK
through much of the day before diminishing during the afternoon.
Should see cigs lower to 4-5kft later this afternoon over E TX,
with the cu cigs expected to gradually nudge ENE into Wrn
LA/extreme SW AR after 00Z Saturday. MVFR cigs should develop
after 06Z over E TX, and possibly by the end of the TAF period
over N LA. IFR cigs may even develop after 09Z over Deep E
TX/Cntrl LA, affecting the LFK terminal. These low cigs will
continue to spread N across the remainder of the region after 12Z
Saturday, but will gradually lift/become VFR by midday/early
afternoon. SE winds 6-11kts today will only diminish slightly to
4-10kts after 00Z. /15/

&&

.PREV DISCUSSION... /issued 428 AM CDT Fri Oct 20 2017/

DISCUSSION...
Moisture return continues in earnest this morning as dew points
range through the 50s from south to north, but low clouds are
still noticeably absent. Pockets of light rain showers are seen
on the SHV radar drifting northward across parts of east Texas,
and this rain is falling out of a mid deck around 10Kft. This
activity is being driven by mid and upper level energy pivoting
northeastward with a shortwave over southeast Texas. This feature
will continue to lift across the region later today with chances
for showers and isolated thunderstorms expanding farther north
and east. Most locations will likely remain dry with the best
chances for rainfall across east Texas where high temperatures
should be held down into the upper 70s due to the excessive cloud
cover and scattered rainfall. The remainder of the region will
continue to hover around the 80 degree mark once again for
afternoon highs. Warm and muggy conditions are expected overnight
with lows only dropping off into the mid to upper 60s by Saturday
morning.

By this time, moisture surge will really begin to accelerate as
dew points climb well into the 60s and even the lower 70s with
isolated to widely scattered convection developing throughout
Saturday. As we move later into the evening, our focus quickly
turns to the strong cold front bearing down on our region from
the northwest as the longwave trough spills out of the Rockies
across the Plains. This open trough is expected to close off at
some point but prior to that, expect a strong line of convection
to develop along the cold front as it advances east of the I-35
corridor into eastern Oklahoma and north central Texas Saturday
evening. As we approach midnight, the line of thunderstorms will
begin encroaching on our northwest zones with a severe potential
in play. The extent of severe weather will depend on instability
which should begin to wane somewhat through early Sunday morning.
The current thinking remains a squall line is likely to develop
and pose a damaging wind threat with embedded bow echoes possible
along the line. Otherwise, the threat appears to be quite minimal
as it relates to large hail and isolated tornadoes with SPC only
including our extreme northwest zones in its Day 2 slight risk.
The line of storms should continue to weaken through the rest of
Sunday morning as conditions become less favorable for sustaining
any severe storms. Thus, the reward does look to outweigh the risk
in the form of beneficial rainfall that is desperately needed over
all of the region. We continue to advertise 1-2 inches on average
for the area through Sunday night with the front clearing the CWA
by that time.

Behind the cold front, expect noticeably cooler and drier air mass
to prevail through much of next week with a reinforcing shot of
cooler air by mid week with a dry Canadian front dropping south
and clipping our region. Temperatures should begin to moderate by
late next week as weak upper ridge builds in behind the departing
longwave trough. In general, expect near normal to slightly below
normal temperatures for the last full week of October with rain
chances holding off until next Friday with the next major cold
front shifting south into the region.

/19/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  81  68  84  70 /  30  20  40  70
MLU  82  65  84  70 /  10  20  40  60
DEQ  79  63  81  64 /  20  20  40  90
TXK  79  65  82  66 /  20  20  40  90
ELD  80  65  82  69 /  10  20  40  70
TYR  78  67  83  65 /  60  30  40  80
GGG  79  66  84  67 /  50  30  40  80
LFK  78  68  84  71 /  60  30  40  60

&&

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

$$

15/19



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