Area Forecast Discussion
Issued by NWS Shreveport, LA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS64 KSHV 201632
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
1132 AM CDT Fri Apr 20 2018

.AVIATION...
Currently, a spring storm to continue slowly deepening across the
Four Corners area of the U.S. to move E into the ArkLaTex region
by Sunday afternoon. A line of TSTMS forecast to develop along a
cold front during Saturday afternoon and sweep E across the
ArkLaTex and NE LA through early Sunday morning. Expect numerous
MVFR ceilings and MVFR VSBY in showers and TSTMS during this time
frame as well. Expect improving conditions to VFR during Sunday
afternoon behind the cold front developing W to E. /VIII/.

&&

.PREV DISCUSSION... /issued 933 AM CDT Fri Apr 20 2018/

UPDATE...
Only minor changes were made to the ongoing forecast. Cirrus
clouds continued to progress eastward across portions of the
Four-State Region with the thickest clouds noted across east TX
and deep east TX. This cloud cover is poised to thin/exit the
region throughout the afternoon giving way to mostly clear skies.
Despite the lack of clouds by the afternoon, temperatures will
remain below normal courtesy of the influence of the nearby
surface ridge. Otherwise, forecast is largely on track with quiet
conditions today will be short-lived as an approaching upper level
disturbance from the west promotes increasing chances for rainfall
by tomorrow.

PREV DISCUSSION... /issued 603 AM CDT Fri Apr 20 2018/

AVIATION...
For the 20/12z TAFs, VFR conditions should continue to prevail at
all terminals for the duration of the period. Mid and high level
clouds will slowly increase in coverage from west to east over the
next 24 hours. Easterly winds around 10 kts will generally
persist during the daytime hours. The winds may be a bit higher
and may gust to between 15 and 20 kts at times at KTYR until
sunset. Convection is expected to develop across Oklahoma and
Texas after 21/06z and gradually move eastward towards the Four
State Region. This convection should remain west of the area
through the end of this TAF period.

/09/

PREV DISCUSSION... /issued 451 AM CDT Fri Apr 20 2018/

DISCUSSION...
The morning sfc analysis indicates sfc ridging extending from the
Midwest SW into Ecntrl TX, which remains progged to persist over
these areas through the day today before weakening tonight.
Meanwhile, satellite imagery indicates a large area of cirrus cigs
which continues to rapidly traverse E across Cntrl and Ern TX
along an amplifying H500 ridge axis, indicative of the changes in
store for the Ark-La-Tex as a closed low over UT/AZ moves into the
Four Corners Region later this morning, before it shifts E into
the Srn Rockies this evening. Should see another day of below
normal temps today, before H850 winds return out of the SSE this
evening ahead of our closed low, and in wake of the departing
ridge. However, the sfc component of the winds will not return out
of the SE until after daybreak Saturday, and even then, the more
humid air will take a better part of the day to return back N into
the region as sfc cyclogenesis shifts E across N TX. Organized
convection should develop this afternoon/evening across much of W
TX ahead of the low, and begin to gradually spread E overnight
over much of OK/Ncntrl TX before reaching Ern OK/Ecntrl TX by
midday Saturday. The attendant warm front should also continue to
shift N across E TX/N LA and possibly into extreme Srn AR Saturday
evening, with the Nwd extent of the front dependent on the track
of the sfc low. Thus, weak instability will spread N with the warm
frontal passage as well, with dynamic forcing increasing Saturday
evening as the upper low tracks E across OK. Thus, the potential
for isolated strong to severe convection will exist primarily
across E TX/Wrn LA, although this threat may be somewhat brief as
the SWrly LLJ shifts E across N LA, and more of a potential for
locally heavy rainfall especially for portions of N LA/Scntrl AR.
Have removed heavy rainfall wording Saturday afternoon, and
tapered wording from W to E Saturday night as drier air aloft
begins to entrain E beneath the closed low into SE OK/E TX.

A return to cooler and drier air will gradually spill SE across
the area Sunday with the cold fropa, but post-frontal
stratus/stratocu and cold advection will result in cooler temps
across E TX/SW AR/SE OK, and possible portions of NW LA. Also
can`t rule out isolated to sct -SHRA developing SSE of the upper
low center, thus have maintained slight chance to chance pops for
the Ern half of the region, with this threat diminishing Sunday
night once the closed low center drifts E across Nrn MS/AL. The
medium range progs suggest that isolated -SHRA may develop Monday
over much of the area as a weak H850 front swings S along the
backside of the upper low, with considerable post-frontal stratocu
maintaining below normal temps over the region.

Should start to see a return of more seasonal temps Tuesday as the
cigs begin to scatter out, although the ECMWF and GFS suggest that
a shortwave will drop SE across the Lower MS Valley Wednesday or
Wednesday night which will result in the return of sct -SHRA.
However, timing uncertainties plague the medium range progs this
morning, but have added low to mid chance pops Wednesday across
the Nrn half of the area along and behind a reinforcing cold front
that is progged to drop S through the region. This front should
only reinforce the drier air back S, with near to slightly below
normal temps expected to persist through the remainder of the
extended.

Prelims to follow below...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  68  50  72  58 /   0  10  50  90
MLU  68  48  75  61 /   0   0  20  90
DEQ  68  48  66  52 /   0  10  80  90
TXK  66  49  68  53 /   0  10  70  90
ELD  67  47  73  58 /   0  10  30  90
TYR  69  50  65  52 /   0  10  70  90
GGG  68  49  68  54 /   0  10  70  90
LFK  70  53  73  59 /   0  10  50  90

&&

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

&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.