Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 252120
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
320 PM CST Thu Feb 25 2021

.SHORT TERM.../Tonight through Friday Night/

The weak cold front has become stationary across the extreme
southern sections of our CWA, generally along a a line from Lufkin
Texas to Jena Louisiana. Noticeably cooler conditions have moved
into the region in wake of the front, with temps running 10 to 15
degrees below this same time on yesterday. Extensive cloud cover
today has also aided in lower temperatures. As expected, starting
to see returns on radar as isentropic ascent starts to ramp up.
Look for this trend to continue through the evening with steady
uptick in upper forcing from the west, as an upper trough moves
out of the Rockies into the Southern Plains.

As the trough to our west moves our way tonight, look for moderate
to heavy rainfall to develop across our region during the
overnight hours, especially in the vicinity of an 850mb theta-e
axis near and north of the I-20 Corridor. There is also a marginal
severe weather threat. With elevated instability across the
region along with effective bulk shear near 50 kts, and mid-level
lapse rates approach 8 C/km, stronger storms could produce hail
above severe limits.

The stalled sfc boundary will return back to the north as a warm
front on Friday, bringing southerly winds and warm air advection
back into the region. The region will remain in southwest flow
aloft, and weak impulses will continue to move across the region.
Although large scale forcing will be diminished as the upper
trough pushes east of the region, rain chances will remain across
the region near the positioning of the stalled sfc boundary. The
best chances appear to be along a corridor from LFK to SHV, to
near MLU. Just how far north this boundary returns will determine
fcst temps on Friday with 70s likely south of the boundary and
50s north of the boundary. /20/


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

SWrly flow aloft will resume Saturday ahead of a longwave trough
that will begin to develop during the afternoon over the Great Basin
and Cntrl Rockies, before amplifying Saturday night/Sunday morning
in the Desert SW. At the sfc, a stationary bndry lingering over
Lower E TX into N LA will begin to lift N as a warm front, with weak
convergence along the retreating front and PVA in the SWrly flow
aloft contributing to sct convection development near and N of the
front. Have increased pops to likely by Saturday afternoon along/N
of the I-30 corridor, with a wide range in temps expected from N to
S with some breaks possible in the strong warm advection regime S of
the front contributing to temps climbing into the mid and upper 70s.
This front should mix N of the region Saturday evening before
stalling, as a cold front begins to shift SE through OK and into the
Ozarks. Thus, moisture pooling will help to enhance continued
convection development across SE OK/SW AR Saturday night, before the
shallow frontal bndry drifts SE into NE TX/SW AR Sunday. Convection
will increase along/ahead of the front Sunday as perturbations
traverse the SW flow ahead of the longwave trough, with pops
increased to categorical for much of the region ahead of the front.

This bndry should gradually shift S through the remainder of the
area Sunday night, although elevated post-frontal isentropic forcing
will continue through Tuesday morning before the parent trough over
the Desert SW quickly ejects NE through the Red River Valley and
into the Ozarks Tuesday. Dry slotting ahead of the trough should
taper the convection from W to E Tuesday, although the shallow post-
frontal air mass does not look to be deep enough to scour the cigs
completely through midweek. Some insolation though should result in
temps returning back to near or above normal through the end of the
long term period.

15


&&

.PREV DISCUSSION... /issued 1229 PM CST Thu Feb 25 2021/

AVIATION...

Frontal boundary has cleared the TAF sites. However, low VFR to
MVFR conditions will continue to overspread the terminals today,
as low ceilings move across the region. Some scattered showers
have started to develop across our extreme southern airspace near
LFK, with precipitation expected to increase in coverage as we
transition into the evening and especially the overnight hours.
Should see ceilings gradually come down to IFR/LIFR ceilings
overnight into tomorrow with the rainfall. Look for NNE to ENE
winds sustained near 10kts for most of the period. /20/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  50  62  54  73 / 100  80  60  50
MLU  51  66  58  75 /  80  60  50  40
DEQ  45  56  45  64 / 100  30  20  70
TXK  47  56  49  65 / 100  70  50  60
ELD  46  57  50  69 / 100  80  70  50
TYR  48  60  52  73 / 100  70  30  50
GGG  48  61  52  73 / 100  80  50  50
LFK  59  73  58  77 /  80  50  40  30

&&

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

$$

20/15



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