Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 271022

Area Forecast Discussion
National Weather Service Shreveport LA
522 AM CDT Mon Mar 27 2017

Sct convection continues to diminish early this morning from W to
E across SW AR/Ncntrl LA as dry air aloft has begun to entrain E
ahead of the closed low as it slowly progresses E across SE KS.
Meanwhile, the morning sfc analysis indicates a weak sfc low over
Ern OK near OKM/MKO, with a trailing weak cold front extending SW
into Srn OK and N TX just W of the I-35 corridor. This front will
continue a slow SE trek into the region later this morning
eventually reaching a HOT to TXK to TYR/PSN line around 18Z before
drifting into extreme NW LA/portions of Deep E TX late in the day.
Deep lyr moisture will remain shallow today ahead of the front,
with given the heating and destabilization today even in absence
of the departing shortwave beneath the closed low, isolated to sct
convection will remain possible especially over Scntrl AR into N
LA/Deep E TX. Was a little more aggressive with the slight chance
pops sliding SE into NE TX/SW AR this morning given the drying
aloft noted immediately beneath the closed low, tapering pops down
for the afternoon into NW LA, while dropping mention of pops for
portions of NE TX/SE OK/adjacent SW AR with the fropa. Even with
the cloud cover expected to linger ahead of the front, the fact
that the 08-09Z temps still remain in the upper 60s/lower 70s will
give us a head start on reaching max temps, thus have bumped
forecast maxes up a bit to the lower/mid 80s ahead of the front.

This front remains progged to pull up stationary later tonight
somewhere over N LA/E TX, with the 06Z GFS coming into line with
the 00Z NAM/ECMWF with a slightly nwd solution closer to the I-20
corridor. The short term progs remain consistent with isolated
convection possibly redeveloping near/just S of the frontal zones
tonight/Tuesday, before it begins to lift back N as a warm front
into Srn AR and SE OK. The warm sector will continue to expand N
into OK and much of AR through Wednesday, as we await the next
weather-maker to our W.

The morning water vapor imagery already depicts this in the form
of an upper trough digging through Cntrl CA attm, which is
expected to deepen tonight as it becomes closed off while
progressing through the Four Corners Region by 12Z Tuesday. This
low should deepen further as it enters the Srn Plains Wednesday,
with the pressure gradient expected to tighten in response to the
strengthening Srly LLJ. Extensive strong to severe convection is
expected to develop Tuesday afternoon/night over W TX/Ern TX
Panhandle into Wrn OK along/ahead of the dryline, while spreading
E across Cntrl/NE OK and Cntrl TX through 12Z Wednesday. The
center of the closed low is expected to drift into the TX/OK
Panhandles Wednesday, with the convection expected to gradually
shift E into E TX/SE OK by midday, slowly marching E across the
remainder of the region during the afternoon/evening. Am more
concerned with the svr potential Wednesday, as the progs have
slowed the ewd progression of the convection down a bit, allowing
for better heating/destabilization for the afternoon especially
across E TX/Wrn LA/SW AR/SE OK, with max temps expected to reach
near 80 to the mid 80s. This should help enhance instability
within a strongly sheared air mass ahead of the closed low,
especially as a split upper jet rounds the base of the low over
Ecntrl/SE TX and the NW Gulf. Thus, storm intensification is
likely with multiple bowing segments possible, enhancing the risk
for damaging winds and isolated tornadoes. Thus, the SPC Day 3
outlook for the Enhanced Risk is certainly justified over much of
the area Wednesday, with these storms expected to gradually march
E across the remainder of the region Wednesday night. Given the
timing uncertainties, have not added svr mention in the forecast
yet but will continue to heighten wording in the morning HWO.

Additional beneficial rainfall will fall with the passage of this
system, with the ECMWF coming more in line with the GFS with dry-
slotting spreading E beneath the closed low Thursday thus quickly
tapering the extent of the convection. Have tapered back pops to
slight/low chance Thursday, with slightly cooler but drier air
filtering ESE in wake of the attendant fropa Thursday
afternoon/evening. Flat ridging aloft is expected to build over
the Srn Plains/Lower MS Valley Friday, but this will be short-
lived as yet another deep closed low is poised to drop S across
the Rockies next weekend, and provide additional rounds of
convection, some of which could again be svr depending on how far
N the warm sector will be able to expand.

Prelims to follow below...



SHV  83  62  84  66 /  30  10  20  20
MLU  82  64  81  63 /  40  20  20  10
DEQ  77  49  76  62 /  20   0  10  40
TXK  80  56  78  64 /  20  10  20  30
ELD  81  59  78  63 /  30  20  20  10
TYR  82  62  83  68 /  20  10  20  40
GGG  82  62  83  68 /  20  10  20  30
LFK  84  66  86  69 /  30  20  20  20




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