Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 201905
AFDSHV

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

.UPDATE...
Quick update to expand isold convection for more of nrn LA and to
change from late aftn to simply aftn per current radar trends.
Also included early eve for same area./07/.

&&

.PREV DISCUSSION... /issued 106 PM CDT Sat Jul 20 2019/

AVIATION...

Morning low clouds beginning to mostly lift to low vfr cigs or
sct cumulus. S-sw winds either side of 10 kts this aftn becmg
south around 5 kts by 21/00z. Increasing high clouds overnight
with these clouds helping to inhibit patchy fog development.
Low clouds overnight may not quite reach the I-20 corridor, but
can expect periods of low clouds and patchy fog by around 21/10z.
Cumulus clouds and sw winds 5 to 10 kts can be expected to begin
around 21/16z with possible scattered convection at mainly kmlu
and keld after the 21/18z fcst cycle./07/.

PREV DISCUSSION... /issued 1036 AM CDT Sat Jul 20 2019/

UPDATE...
Fairly dry and capped airmass to inhibit any convection this aftn,
with only isold late aftn convection possible closer to the MS
river valley where JAN 12z sounding to the east quite moist. Most
temps should reach mid 90s and heat indices 100 to 105 degrees. No
update needed./07/.

PREV DISCUSSION... /issued 444 AM CDT Sat Jul 20 2019/

SHORT TERM.../Today through Sunday/

Fair skies with some high clouds arriving on the Easterlies.
Air temperatures are in the mid to upper 70s with 81 the warmest
downtown Shreveport and a handful of 74s for the coolest. Our
winds are light S/SW with a few sites calm with some patchy fog.

It looks a lot like yesterday with just a few more clouds around
today and the heat index again near 105. This peak heating will
allow for a few pop up showers or a thunderstorm this afternoon as
moisture continues to increase from the East. Believe it or not,
some of Barry`s left overs rotating under the weakening upper
ridge.

Muggy and mild with mid 70s overnight and a bit more cloud cover
for Sunday with highs in the lower 90s for the most part. All due
to increasing clouds and humidity with a slightly better sea
breeze with thunderstorms on Sunday. The SPC has a general risk
for us both today and tomorrow from Lufkin to Monroe. /24/

LONG TERM.../Sunday Night through Friday Night/

The weak Erly wave (which originated from the remnants of Barry over
GA/AL Friday), is progged to drift W into E TX Sunday evening, with
any isolated/sct convection expected to diminish with the loss of
heating. Did maintain slight chance pops during the evening over
portions of extreme Ern TX/N LA/Scntrl AR to account for any
remaining convection, as we await a longwave trough and associated
weak sfc front that will dig SSE into the MS/OH Vallies. This trough
will allow for the dominant upper ridging in place from the Rockies
E into the Mid-Atlantic region to retreat W over the Four Corners
Region, with the sfc front not expected to mix S into the Red River
Valley into Cntrl AR until Monday afternoon. While the weakness
aloft over E TX Sunday evening is progged to drift further SW into
SE TX/NW Gulf Monday around the Four Corners ridge, a portion of
this weakness may linger over Deep E TX into N LA/Scntrl AR during
the afternoon, with diurnal heating contributing to sct convection
developing over these areas. However, GFS/ECMWF/Canadian have slowed
the entrance of the aforementioned longwave trough/frontal influence
in our area until Monday night, and thus have maintained low to mid
chance pops over the area Monday afternoon with the convection
primarily outflow driven given the weak shear and lack of any
convergence.

This should change though Monday night as the frontal convergence
increases once the front slips S to the I-30 corridor of NE TX/SW
AR, with sct/numerous convection increasing Monday evening between
the I-30 and I-20 corridors. Have maintained likely pops for this
area Monday night, tapering to high chance across much of the
remainder of the region given the consensus amongst the GFS/ECMWF.
This convection should diminish from N to S Tuesday as the drier
post-frontal air begins to deepen with the departure of the sfc
front/accompanying H850 trough, but did keep high chance pops going
during the morning for Lower E TX/Srn sections of Ncntrl LA before
lowering pops for the afternoon. Max temps Tuesday look to trend at
least some 7-10+ degrees below normal with the lingering rains/post-
frontal cloud cover, with the noticeably drier air spilling S in
wake of the fropa. Did keep low pops going across the Srn zones
Tuesday evening to account for any residual convection along the
lingering H850 trough, with any cigs clearing late.

Sfc ridging from the Midwest SSW into Cntrl TX will linger for the
middle and latter half of the new work week, with a dry nrly flow
aloft maintaining stable conditions over the area as the Gulf will
remain cut off. Below normal temps/humidity will also be a welcome
sight Wednesday and Thursday with the sfc ridging in place, with
temps expected to range some 4-8 degrees below normal, with min
temps falling below 70 areawide for a change. Differences arise by
Friday though amongst the GFS/ECMWF, with the GFS maintaining dry
conditions over the region through all of next weekend. Meanwhile,
the ECMWF suggests that low level moisture will begin to deepen over
Ncntrl and NE LA as higher PW air is advected slowly NW from SE LA,
and for this reason, did include slight chance pops returning Friday
afternoon for Deep E TX into Ncntrl LA, expanding these pops farther
NW across the I-20 corridor of E TX into Scntrl AR Saturday as low
level moisture continues to gradually deepen/expand back NW. Thus,
the nice reprieve of cooler/less humid air will not last long as the
usual hot and humid conditions will return to the region by late
week into next weekend. /15/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  95  76  93  76 /  10  10  20  20
MLU  94  75  91  74 /  10  10  40  20
DEQ  93  74  92  73 /  10  10  10  10
TXK  93  76  91  75 /  10  10  10  10
ELD  93  75  91  74 /  10  10  30  20
TYR  93  75  95  76 /  10  10  10  10
GGG  95  75  94  75 /  10  10  20  10
LFK  94  75  92  74 /  10  10  30  20

&&

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

$$



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