Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 210757
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
257 AM CDT Sun May 21 2017

.DISCUSSION...

Despite being well removed from the vigorous upper level
trough across the Northern Plains into the Upper Great Lakes
region of the country, we continue to deal with isolated to
scattered convection across portions of the Four State Region
early this morning. This due in part to a myriad of convective
outflow boundaries, not to mention residual instability from some
atmospheric recovery from Sat Aftn, a weak sfc cold front making
slow progress into our region and weak upper level perturbations
in west southwest flow aloft across East Texas into Northern
Louisiana and Southern Arkansas.

Cold front as of 06z was oriented near a LZK...TXK...PSN line and
was continuing to make slow but steady progress south and east
early this morning. The front should continue moving southeast
during the day, moving through all but our extreme southeast
parishes of Northern Louisiana by this afternoon. Seeing some
elevated convection currently to the north and west of the
Interstate 30 corridor of Northeast Texas and Southwest Arkansas
with this convection oriented along the 850mb front which has made
just about as much progress south and east as it will make today.
For this reason, cannot rule out additional prefrontal and post
frontal showers and thunderstorms once again today but the best
coverage should be across our southern most zones through this
afternoon. Models continue to indicate an embedded disturbance in
this WSW flow aloft moving our way quickly tonight from the TX
Hill Country. Our southwest zones will be in the left front exit
region of a 70-90kt upper level jet oriented west to east across
Central TX late tonight which should allow for good upper level
forcing despite a rather stable post frontal boundary layer across
our region. The NAM output continues to be the most vigorous with
convection overnight but the GFS and ECMWF are trying to play
catchup so to speak so have beefed up pops tonight, especially
after midnight tonight and through the day Monday for the above
reasons. The highest rain chances will be felt across our southern
third tonight through Monday before we lose the effects of the
disturbance to our east.

Beyond Monday, we look upstream once again to our north and west
as another strong shortwave splits off the Upper Great Lakes
trough and moves due south into the Central and Southern Plains
late Monday Night into Tuesday. Strong PVA signal in advance of
what will become a developing longwave trough across the Mid Miss
Valley, resulting in increased chances of showers and
thunderstorms once again Tue along and ahead of a cold front which
should blow through our region Tue Night. The trough appears to
cut itself off a little further north and east of our region
Wed/Wed Night which may limit post frontal shower activity Wed/Wed
Night but none the less, much cooler airmass will be felt behind
this cold front for Wed into Thu. Still forecasting overnight lows
in the upper 40s to lower-mid 50s for next Wed Night/Thu morning
with a quick moderation in temperatures for the upcoming weekend
on the heels of returning southerly flow. Southwest flow aloft
commencing once again for next weekend suggests scattered showers
and thunderstorms returning to the region as well by this
timeframe.

Prelims to follow...13.

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  79  62  71  60 /  40  50  60  40
MLU  80  62  72  59 /  40  40  60  40
DEQ  78  55  74  57 /  10  10  20  40
TXK  78  59  72  57 /  20  20  30  40
ELD  78  56  73  57 /  20  20  60  30
TYR  77  62  74  61 /  40  50  50  40
GGG  78  62  72  59 /  40  50  60  40
LFK  80  66  73  62 /  50  60  70  40

&&

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

$$

13


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