Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 281140
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
640 AM CDT Wed Jul 28 2021

.AVIATION...

For the 28/012Z TAFs, VFR conditions will prevail through the day
at all terminals, outside of afternoon thunderstorms. Including
VCSH for LFK in the late morning hours, and VCTS for terminals
along and south of I-20 during the late afternoon hours. Storms
should diminish in coverage by 29/00Z. Light and variable winds
will become nearly calm overnight, allowing for some patchy BR/HZ
at daybreak. /26/

&&

.PREV DISCUSSION... /issued 354 AM CDT Wed Jul 28 2021/

SHORT TERM.../Today through Thursday/

The upper level ridge to our northwest over the Central Plains
will remain in a position quite similar to yesterday, setting the
stage for another day characterized by very high dewpoints and
afternoon convection. Some isolated showers and thunderstorms may
already be in progress by 12Z across deep east Texas and lower-end
PoPs remain across our southwestern zones through the morning
hours. After 18Z, PoPs begin to climb across our southernmost
counties and parishes, spreading northwards through the afternoon
hours. Between 21Z and 00Z, the development of storms looks to
spread across much of the area south of the I-20 corridor. Their
closer proximity to the upper-level ridge will keep our
northwestern zones dry through the afternoon.

High temperatures today will once again quickly climb into the
middle 90s areawide, with the highest temperatures across
southwest Arkansas and southeast Oklahoma, where the chances of
any rain-cooling effects are the least. Deep east Texas and
northwest / north central Louisiana look likely to max out at
highs 2-3 degrees cooler than those to the north, thanks to the
cloud cover and rain-cooling associated with anticipated
convection across these zones this morning and afternoon.

That being said, the entire Four State Area remains under a Heat
Advisory today, in effect from 12:00 noon to 7:00 PM CDT. There
will be little to no relief from the unrelentingly muggy airmass
we are mired in until afternoon convection fires up. Dewpoints
will start out in the middle 70s areawide at daybreak and will
only climb through the morning hours, quickly driving heat indices
above 100 degrees areawide. Peak heat indices will top out
between 105 and 110F at most sites by midafternoon.

Thursday will keep this week`s pattern very much alive, as the
upper level ridge begins to spread southeastward. Overnight lows
will fall into the mid to upper 70s before climbing back into the
mid to upper 90s Thursday afternoon. Dewpoints in the mid 70s will
make for another very muggy afternoon featuring heat indices in
excess of 100 degrees across the ArkLaTex. The progression of the
ridge will again keep afternoon showers and thunderstorms from
progressing north of the I-20 corridor. /26/

LONG TERM.../Thursday Night through Tuesday Night/

Upper ridging will remain firmly entrenched from the Cntrl Plains SE
across the Lower MS Valley and into the SE CONUS Thursday night,
with the center of the ridge still progged to drift SE into SE KS/NE
OK/NW AR Friday. Enough of a weakness may still remain along the Srn
periphery of the ridge across Deep E TX/Cntrl LA Friday and Saturday
afternoons to allow for very isolated convection to develop over
these areas, but otherwise, very hot and mostly dry conditions are
expected through Saturday afternoon. The NBM continues its warm bias
with max temps Friday through the weekend, and thus have continued
to trim back temps 1-2 degrees, with readings still shy but nearing
the triple digits across portions of SE OK/extreme NE TX/SW
AR/extreme Nrn LA as the ridge center begins to flatten but still
drifting into the region. Despite some mixing of dewpoints,
particularly across portions of E TX, resultant heat indices will
still reach/exceed 105 degrees over much of the area, with the
ongoing Heat Advisories likely being extended through the upcoming
weekend.

A welcome change remains progged to take place during the latter
half of the weekend, as a longwave trough begins to dig SSE from the
Midwest into the OH valley, with the tail end of the trough expected
to sink S through OK/AR. This will displace the ridging aloft
farther W back over the Rockies, with convection expected to
increase Sunday afternoon ahead of an attendant cool front that will
be convectively reinforced S from Cntrl OK into much of AR. Ahead of
this convection though, another day of near triple digit heat is
expected, although the progs have trended a bit faster with
convection spreading S into portions of SE OK/Nrn sections of SW AR
Sunday afternoon near the front. Have trended pops up to mid chance
over these areas, with the convection spreading S into NE TX/the
remainder of SW AR/portions of N LA Sunday night. There is
variability though with regards to the timing of convection, with
the GFS a bit more aggressive than the ECMWF. Given these
uncertainties, have cut back on the likely NBM pops to mid and high
chance over the region Sunday night and Monday, which should result
in cooler temps and relief to the ongoing heat. The front should be
reinforced into E TX/N LA Monday, but the ECMWF is a bit slower in
mixing the front S and thus, maintaining sct convection along the
frontal sfc across Lower E TX/N LA Monday night and Tuesday. Drier
air in wake of the trough passage aloft should finally mix SE of the
region by Tuesday night, ushering in a return to dry conditions as
well as slightly drier air at the sfc. This should result in near to
slightly below normal temps persisting in the dry NW flow aloft
through at least midweek.

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  95  77  97  77 /  30  10  20   0
MLU  94  77  96  77 /  30  10  20   0
DEQ  96  75  98  75 /  10   0   0   0
TXK  96  77  98  78 /  10   0  10   0
ELD  95  74  97  75 /  20   0  10   0
TYR  94  77  96  77 /  20  10  20   0
GGG  94  76  96  76 /  30  10  20   0
LFK  95  77  96  75 /  50  20  30  10

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Heat Advisory from noon today to 7 PM CDT this evening for
     ARZ050-051-059>061-070>073.

LA...Heat Advisory from noon today to 7 PM CDT this evening for
     LAZ001>006-010>014-017>022.

OK...Heat Advisory from noon today to 7 PM CDT this evening for
     OKZ077.

TX...Heat Advisory from noon today to 7 PM CDT this evening for
     TXZ096-097-108>112-124>126-136>138-149>153-165>167.

&&

$$

26/26/15


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