Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 270849
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
349 AM CDT Tue Jul 27 2021

.SHORT TERM.../Today through Wednesday/

The hot conditions experienced across the Four State Region
yesterday will be in store again today and Wednesday, as we will
see little to no changes in the prevailing synoptic pattern. The
upper level ridge parked over the Rockies and Plains is positioned
to continue to keep us in a hot, muggy regime throughout the
short term forecast period.

Very muggy dewpoints this morning will have little chance to dry
out by early afternoon, remaining in the mid to upper 70s across
much of the area, in particular our eastern zones. Ambient
temperatures will quickly climb back into the mid 90s areawide by
18Z, and when combined with the oppressive dewpoints, will result
in heat indices in excess of 105F at most locations. For this
reason, a Heat Advisory remains in effect today from 12:00 noon
through 7:00 PM CDT.

The persistently muggy conditions described above will also prime
much of the region to be favorable for the development of showers
and thunderstorms through the afternoon hours. Any lingering
overnight convection will barely have a chance to dissipate before
dirunal heating fires off new convective development as early as
18Z across north central Louisiana, spreading north and westward
across the entire Four State Region between 21Z and 00Z.
Convection will diminish after sunset as temperatures again fall
to overnight lows in the mid 70s areawide.

A near repeat performance is in store for Wednesday, with
dewpoints in the mid 70s coupled with high temperatures in the mid
90s. PoPs begin to climb again as early as 12Z, increasing into
the afternoon. Chances of afternoon thunderstorms Wednesday will
be highest south of I-20, consistent with a sea breeze convection
setup. /26/

.LONG TERM.../Wednesday Night through Monday Night/

Upper ridging centered over Srn NE/much of KS Wednesday night will
continue to expand SE into the Lower MS Valley and portions of the
SE CONUS, eventually encompassing much of the region by Thursday,
resulting in even hotter temps for the late week/weekend timeframe,
as well as mostly dry conditions. A weakness aloft lingering along
the Srn periphery of the ridge axis should continue to result in the
potential for isolated afternoon convection Thursday through
Saturday across portions of Deep E TX/NCntrl LA S of the I-20
corridor. The NBM continues its warm bias with max temps through
much of the long term period, but given that continued greenup,
remaining soil moisture, and that the ridge center will remain NW of
the region over KS/NE OK through Friday, have continued the trend of
cutting back max temps 1-2 degrees and just shy of the century mark
across SE OK/SW AR/NE TX/NW LA. Unfortunately, mixing of dewpoints
will be limited each day, with heat indices expected to near or
exceed 105 degrees over much of the region through the upcoming
weekend, thus necessitating the need for additional Heat Advisories
through this portion of the forecast.

However, some promise of relief may be in the offing late this
weekend and especially early next week, as an upper level pattern
change remains progged as a longwave trough begins to dig S along
and E of the MS Valley, reinforcing a weak cool front into NCntrl
OK/AR Sunday, with this bndry slowly slipping S into the Red River
Valley of Srn OK/N TX into Srn AR by early Monday. This trough will
help to weaken the ridging aloft in place over the region late this
weekend, with the ridge retrograding W into W TX and much of the
Rockies. The GFS and now the Canadian have come along closer to the
ECMWF with regards to this trough developing farther W, with
convection expected to increase along the frontal bndry Sunday
through Sunday night, persisting as it enters SE OK/portions of SW
AR by early Monday. Have increased pops to low chance for these
areas, with sct convection expected to increase over much of the
region Monday/Monday night as the weak frontal bndry sags S into E
TX/N LA. Depending on whether the convection persists along/ahead of
the bndry or not, compressional warming may be factor with max temps
Monday, but did increase pops to low/mid chance Monday to account
for this increase in convection expected especially with the aid of
diurnal heating. This convection may reinforce the bndry S of the
area by Tuesday, with any remaining convection expected to diminish
with the fropa. But fortunately, slightly cooler temps are
suggesting amongst the medium range progs afterwards and thus
bringing some temporary relief to the oppressive heat.

15

&&

.PREV DISCUSSION... /issued 1230 AM CDT Tue Jul 27 2021/

AVIATION...

For the 27/06Z TAFs, VFR conditions will prevail through the
overnight hours. Winds will be nearly calm at most terminals, and
the humid environment will be favorable for the development of fog
between 27/08Z-27/12Z. Carrying MVFR vis at SHV/TXK, IFR at
MLU/LFK, and LIFR at ELD. Fog should burn off by 27/15Z, after
which VFR will prevail outside of thunderstorms. VCTS possible at
all area terminals in the afternoon hours. Storms will diminish by
28/00Z and light and variable winds will calm after sunset. /26/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  97  77  97  77 /  50  20  50   0
MLU  95  76  94  76 /  60  20  50   0
DEQ  95  74  96  75 /  30  10  20   0
TXK  97  77  96  77 /  40  10  20   0
ELD  95  74  94  74 /  40  20  30   0
TYR  96  77  94  77 /  30  10  30   0
GGG  95  75  94  76 /  40  20  40   0
LFK  97  76  96  75 /  50  20  50  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.

&&

$$

26/15


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