Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 210217

Area Forecast Discussion
National Weather Service Shreveport LA
917 PM CDT Sat Jul 20 2019

Aside from a lingering thunderstorm across Natchitoches parish
this evening, stable conditions prevail across the ArkLaTex.
Earlier convection across southern Louisiana  has contributed to
substantial high clouds across the eastern half of the forecast
area, which is well represented in the grids at this time. Clouds
to gradually diminish overnight to be possibly replaced by low
clouds, mainly along and south of I-20, by daybreak. Otherwise,
overnight lows to fall into the mid 70s. Forecast is on track, no
update at this time. /05/


.PREV DISCUSSION... /issued 645 PM CDT Sat Jul 20 2019/

VFR conditions to become MVFR around daybreak across area
terminals as low clouds stream north across the region. Skies to
improve to VFR by 21/15Z. VCTS conditions will be possible in the
afternoon across LFK/SHV/MLU/ELD terminal sites. Otherwise, south
winds around 5 knots overnight to become 5 to 10 knots on Sunday.

PREV DISCUSSION... /issued 353 PM CDT Sat Jul 20 2019/

SHORT TERM.../Tonight through Sunday Night/

Upper ridge holding over TX bringing area continued lower to
middle 90s heat with dewpoints in 70s, mixing down just enough
durg the day to keep heat indices mostly under 105 degrees. A
few isold showers poking into se portions of cwa with moisture
which will begin to advect eastward the next couple of days while
upper ridge retrogrades into NM. Can expect isold to sct coverage
by Sun aftn across at least the se half of the cwa, including all
of nrn LA. Steep low lvl lapse rates and westerly component of
storm motion suggest gusty wind potential in storms that develop.
Convection will last further into the eve hours on Sunday but
expect things to be quiet after midnight as nw flow will still be
just upstream of cwa by then./07/.

LONG TERM.../Monday into next weekend/

Bottom line, up front: The cold frontal passage expected for early
next week still looks on track and will usher in below normal heat
and humidity for Tuesday through the bulk of the rest of the work

The front will actually be dropping in from the north on Monday, but
oppressive heat will continue for many through the greater part of
the day (especially over East Texas). Over the past several days,
southerly winds have helped with boundary-layer mixing, keeping
temperatures and heat indices from peaking as high as they might
otherwise. However, on Monday, expect lighter winds (with a hotter
westerly component) setting up ahead of the incoming front. For now
I have boosted blended guidance temperatures in many locations, but
still may not be hot enough. Of course, the prospect of at least
widely scattered, diurnally-driven, showers and thunderstorms in the
afternoon may provide a little relief (although probably mostly east
of the Arklatex). In short, conditions close to heat advisory
criteria may be in the works for Monday for at least western zones.

Model consensus suggests the cold front pushing south across the
Four State region between Monday evening and Tuesday morning. Low to
mid layer wind shear values expected along and ahead of the front
appear too marginal for anything more than brief organization of
linear thunderstorm line segments (i.e., the threat for severe
weather from gusty winds is not zero - but not high enough to
highlight in the HWO). There are still some sporadic bullseyes of
rainfall values showing up in model guidance and indeed relatively
slow storm motions could lead to isolated pockets of 1 to 2 inch
amounts. However, given recent dryness in the bulk of the area,
these rains are not anticipated to cause a flooding problem. We
anticipate showers and embedded thunderstorms may lag the actual
frontal zone by 50 to 100 miles and all rain may not exit to the
south until Tuesday afternoon or early Tuesday evening.

Thereafter, the seasonably pleasant drier and less-hot stretch will
commence. Tuesday through Thursday will mainly feature lows in the
low to mid 60s with highs in the mid to upper 80s. An isolated
sheltered spot north of I-20 Tuesday and/or Wednesday night may be
able to crack into the upper 50s, but that is not yet in the
official forecast.

Model consensus suggests the stalled front near the coast will wash
out late next week and returning southeasterly winds will infiltrate
humidity back in gradually while heat slowly increases. Fortunately,
the return to typical late-July heat in many areas by next weekend
is not a sure thing as weak troughing to the lee of the staunch
western CONUS ridge could produce enough clouds and precipitation to
limit insolation. /50/


SHV  76  93  76  95 /   0  20  20  40
MLU  75  89  75  91 /  20  30  30  50
DEQ  75  93  74  94 /   0   0   0  40
TXK  76  92  75  93 /   0  10  10  40
ELD  76  92  76  92 /   0  20  20  50
TYR  77  94  76  96 /   0   0   0  20
GGG  76  93  76  96 /   0  10  10  30
LFK  75  91  76  94 /   0  30  20  40




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