Area Forecast Discussion
Issued by NWS Shreveport, LA
FXUS64 KSHV 220341
Area Forecast Discussion
National Weather Service Shreveport LA
941 PM CST Sat Jan 21 2017
Tor watch in effect until 9 pm had to be extended until midnight
for north central La and extreme south central AR, as a persistent
band of stg to svr redeveloping tstms btwn I-20 and AR state line.
Also raised overnight lows a few degrees given continued cloud
cover and dew point trends./VII/.
.PREV DISCUSSION... /issued 314 PM CST Sat Jan 21 2017/
A sheared and highly unstable atmosphere awaiting trigger for
convection to rapidly occur later this aftn. Special 18z soundings
at KSHV and KLZK showing dry adiabatic lapse rates in the 800-600
mb layer. Fairly lgt winds at sfc keeping low lvl shear at
moderately high lvls and suggesting primary threat to be very
large hail in storms, but still with existence of tornado and
damaging wind threat. Storm initiation expected within next hour
or two at the most...across se OK and extreme eastern TX, with
storms intensifying by early eve as they track across north LA
into sw AR. Commahead shape of this upper low as it wraps around
backside of low, will bring moisture swd back into area later
Sunday mrng. Low topped convection may occur with continued steep
mid lvl lapse rates beneath a stg upper lvl inversion. Low lvl
speed shear indicated in sfc westerly to nw wind veering profile.
Cold core low hail threat appear possible with this convection
although overall coverage will be low, should it materialize at
all. Cooler air finally movg into area with overnight lows back
into the 40s early next week, and mostly zonal flow suggest that
at least a few days of dry wx upcoming thru extended period./VII/.
PREV DISCUSSION... /issued 249 PM CST Sat Jan 21 2017/
For the 21/18Z terminal forecast, will start out with many sites
having IFR/MVFR flight categories prevailing. Some of the sites
will be returning to VFR as clouds lift. Showers and
thunderstorms possible after 21/23Z and lasting into the middle of
the evening hours. Other sites will be seeing the thunderstorms
developing later in the evening and continue until around 22/06Z.
Convection to exit the region to the east after 22/08Z but
may return early Sunday morning around the back side of the upper
low pressure system that moves along the Red River Valley Region.
South to Southwest winds 7-12 knots and increasing overnight
and shifting to the West and Northwest around day break and into
the mid morning hours to 15-20 knots with higher gusts with front.
PREV DISCUSSION... /issued 942 AM CST Sat Jan 21 2017/
No update needed at this time. The Forecast is on track with
showers and thunderstorms moving into the area by late this
afternoon, along with severe weather through the overnight hours.
Shreveport will do a special 18z sounding to sample the atmospheric
conditions ahead of the severe weather.
.PRELIMINARY POINT TEMPS/POPS...
SHV 51 64 43 65 / 20 20 0 0
MLU 54 64 43 62 / 50 30 10 0
DEQ 47 60 37 61 / 20 30 0 0
TXK 50 61 40 62 / 20 30 0 0
ELD 51 62 40 62 / 20 30 10 0
TYR 50 63 43 66 / 20 10 0 0
GGG 50 63 42 64 / 20 10 0 0
LFK 52 65 43 67 / 20 10 0 0
AR...Lake Wind Advisory from 9 AM to 9 PM CST Sunday for ARZ050-051-
LA...Lake Wind Advisory from 9 AM to 9 PM CST Sunday for LAZ001>006-
OK...Lake Wind Advisory from 9 AM to 9 PM CST Sunday for OKZ077.
TX...Lake Wind Advisory from 9 AM to 9 PM CST Sunday for TXZ096-097-