National Weather Service Raw Text Product

Displaying AFOS PIL: AFDSHV Received: 2018-10-12 09:48 UTC


528 
FXUS64 KSHV 120948
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
448 AM CDT Fri Oct 12 2018

.SHORT TERM.../Today through Saturday/

A shortwave trough will quickly move eastward across the Central 
Plains and into the Ohio River Valley by tonight. Isentropic 
ascent ahead of this shortwave has already resulted in a large 
area of showers and isolated thunderstorms across much of 
Oklahoma. The isentropic ascent and associated precipitation will 
move east and southeast today along with the upper trough. Most of
the rain should dissipate by midnight as the shortwave moves well
east of the area and vertical ascent weakens. Rainfall amounts 
should be less than one half inch today, and the highest totals 
should be in extreme Northeast Texas and Southeast Oklahoma. The 
cloud cover and rain will have a noticeable effect on temperatures
and should result in a fairly large gradient across the forecast 
area. Daytime highs will likely remain in the 60s where the showers
prevail, but temperatures may approach 80 degrees F farther south
and southeast where rain chances are lowest.

By sunrise Saturday morning, the remnants of Tropical Storm Sergio 
should be emerging into West Texas. As the surface low continues 
east- northeast, a warm front will develop roughly along the Red 
River between Oklahoma and Texas eastward across Southern 
Arkansas. Abundant deep-layer moisture and increasing low-level 
moisture should result in widespread showers and a few 
thunderstorms across the Southern Plains near the warm front. 
Some of these showers may begin to affect portions of East Texas 
just before sunrise Saturday. However, rain chances will increase 
dramatically after sunrise and into the afternoon across all but 
our southeastern- most parishes of Central Louisiana. The highest 
rain chances and highest rainfall totals should be west of a line 
from Tyler Texas to Nashville Arkansas. The potential for locally 
heavy rain will persist well past the short-term forecast period 
and is detailed in the long-term discussion below.

CN

.LONG TERM.../Saturday Night through Thursday Night/

Low level warm and moist advection will continue Saturday night, as 
a sfc low develops over NW TX along a weak frontal zone, and slides 
ENE across the Red River Valley over Srn Ok/N TX Saturday night. 
This will come on the heels of the remnants of Sergio, as it rapidly 
shifts ENE into and E of the MS Valley. A 35-45kt SWrly LLJ is 
progged to develop Saturday night over N and Ecntrl TX into SE OK 
Saturday night, which will interact with lingering shortwave energy 
in the developing SW flow aloft ahead of positive tilted longwave 
troughing from the Nrn Plains SW into the Four Corners Region, and 
strong frontogenetical forcing in the H850-700 lyr near and N of the 
weak sfc front, to result in increasing convection Saturday night 
across portions of extreme NE TX/SE OK/adjacent sections of SW AR. 
Have continued with categorical pops over SE OK/adjacent sections of 
SW AR Saturday night, and carried likely pops to the I-30 corridor, 
before ramping pops up late a little farther SE of I-30, as the 
convection gradually builds more SE. Large scale forcing looks to 
weaken by/shortly after 12Z Sunday as the mean flow becomes 
unidirectional ahead of the front, which will linger from N TX NE 
into extreme SE OK/Wrn and Cntrl AR through much of the day before 
deepening post frontal colder air and pressure rises over KS/OK 
finally begin to reinforce this front SE into the area Sunday night. 

Convection should again increase Sunday night as subtropical 
moisture from the Ern Pacific is advected NE along/just ahead of the 
trough axis, and convergence increases along the H850 front over 
Cntrl TX into SE OK/Wrn AR. Have beefed up pops back to categorical 
Sunday night for NE TX/SE OK/SW AR behind the sfc front, as it oozes 
SE into portions of Deep E TX/NW LA/Scntrl AR by 12Z Monday. 
Convergence along the H850 front is progged to weaken during the day 
Monday, as the front continues to slowly drift S through the 
remainder of the region. Could see max temps Monday reached during 
the morning across portions of Deep E TX/NW LA, with temps falling 
during the day as cold advection commences with the passing front. 
Much below normal temps are expected through much of next week as 
persistent post-frontal cloud cover lingers and periods of -SHRA 
affect the area, as SW flow aloft will persist over the Srn Plains, 
allowing for weak impulses aloft to interact with the old H850 front 
which looks to linger across Ncntrl and NE TX/SE OK through at least 
midweek before weakening. Low confidence in the rainfall axis 
precludes pop mention any higher than chance attm, as this unsettled 
weather pattern looks to continue through the remainder of the week. 

15

&&

.PREV DISCUSSION... /issued 1209 AM CDT Fri Oct 12 2018/ 

AVIATION...

For the 11/06Z terminal forecast will prevail VFR for all sites 
across the ArkLaTex. Middle and high clouds will be spreading over
the sites overnight and lowering during the early to mid morning 
Friday between 5-8 kft. Showers will spread in from the West and 
Northwest affecting KTYR, KELD and KTXK in the afternoon and 
early evening. Surface winds will be light and variable to light 
Northeast less than 6 knots overnight and East to Southeast 5-10 
knots Friday and becoming variable in the afternoon. /06/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  73  60  77  69 /  40  20  30  30 
MLU  73  59  77  66 /  30  10  20  10 
DEQ  62  55  64  60 /  60  20  90  80 
TXK  66  56  67  64 /  50  20  60  70 
ELD  71  56  69  64 /  40  20  40  40 
TYR  73  60  76  69 /  40  30  60  60 
GGG  74  59  77  69 /  40  30  40  50 
LFK  78  63  83  70 /  20  10  20  20 

&&

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

$$

09/15