000
FXUS64 KSHV 311126
AFDSHV
Area Forecast Discussion
National Weather Service Shreveport LA
626 AM CDT Sat Jul 31 2021
.AVIATION...
While VFR conditions are anticipated for this entire TAF period,
some MVFR visibilities can currently be found at KELD and KMLU.
This reduced vis should quickly mix out as the morning progresses.
/44/
&&
.PREV DISCUSSION... /issued 340 AM CDT Sat Jul 31 2021/
SHORT TERM.../Today through Tomorrow/
Make sure your coffee is iced, and morning shower cold before you
head out the door, because those things may be the only relief
you have from heat until Monday. It goes without saying, but
oppressive afternoon heat index values will continue to be the
main weather story over the next 36-hours under relentless upper-
level ridging. This ridge will be maximized today, which has
resulted in me expanding the Excessive Heat Warning that was
previously in place. The new warning covers all of our Louisiana
parishes, with the Heat Advisory continuing for all other portions
of the Four-States region. One thing of note regarding
temperatures, while the ridge is strongest today, I`ve actually
slightly trimmed back afternoon highs compared to tomorrow. As the
ridge breaks down ahead of the approaching trough and front in the
long-term, I think tomorrow will allow for some compressional
heating to take place ahead of that aforementioned front. As such,
tomorrow will be the first day I put triple-digits in the grids
for Shreveport proper, with widespread triple-digits elsewhere.
Regarding PoPs, most of this period continues to look dry. This
will change by Sunday night when that front begins to move
through the region. However, while there are no PoPs in the
forecast for today, I`m not entirely convinced the entire area
will remain dry. Given nuclear afternoon CAPE values, its entirely
possible the flap of a birds wing will be enough to set off a few
towers. Again, I do not have enough confidence to include
coverage in this forecast, but I wouldn`t be surprised if someone
got some thunder this afternoon.
/44/
LONG TERM.../Sunday Night through Friday Night/
At the start of the long-term period, the flow aloft will be
characterized by a highly amplified upper ridge over the Western
CONUS and a longwave trough over the Eastern CONUS/Eastern Canada.
Northwesterly flow aloft will bring a series of shortwave troughs
southeast across the Southern Plains and Mid/Lower Mississippi River
Valley. The first of these will move across the forecast area Sunday
night and during the day Monday. At the surface, a cold front will
be slowly moving south across the area and should be located near
the Interstate 30 corridor Sunday evening. Scattered to widespread
showers and thunderstorms should be ongoing both along and ahead of
the frontal boundary. The convection should become more focused
along the front during the day Monday as the shortwave trough moves
overhead. CAPE values should generally range from 2000-3000 J/kg in
the warm sector, but weak deep layer shear and lapse rates should
keep the overall severe weather potential limited. However, an
isolated severe storm or two with the potential for damaging winds
will be possible during the day Monday, especially along and south
of I-20.
The cold front should finally move south of the area Monday
night/early Tuesday morning, and showers and thunderstorms should
diminish from north to south as northerly winds advect considerably
drier low-level air into the region. The front will likely stall
just north of the I-10 corridor, with the 850 hPa front lagging
behind over Deep East Texas and Central Louisiana. Another weak
shortwave translating southeast over the area should result in more
scattered showers and thunderstorms across Texas and Louisiana south
of I-20, but with considerably lower coverage compared to Monday.
Dry weather should return Tuesday night, and the medium range models
are far less aggressive with precip chances after Wednesday compared
to previous runs. Another shortwave moving southeast should help to
push the front a little farther south, most likely far enough to
keep our precip chances very low for Wednesday, but I did hold on to
some slight-chance PoPs during peak afternoon heating south of I-20.
The ECMWF still maintains that the front may retreat northward on
Thursday, which would improve our rain chances, but not by much. The
front is expected to dissipate by Friday allowing southerly surface
flow and Gulf moisture to return. This will bring back the pattern
of isolated to widely scattered diurnal convection on a daily basis.
The big story will be the significantly cooler temperatures
beginning Monday. Daytime highs will likely fall back into the upper
80s to lower 90s and should generally hold steady through Thursday.
However, a warming trend is expected towards the end of the work
week and into the weekend, but temperatures should remain well below
the century mark through at least next Friday.
CN
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 99 80 100 76 / 10 0 30 60
MLU 99 79 99 74 / 10 10 40 70
DEQ 98 76 99 71 / 0 0 50 60
TXK 99 79 100 73 / 0 0 40 60
ELD 99 77 99 71 / 0 0 40 70
TYR 96 78 98 76 / 0 0 20 50
GGG 96 77 98 75 / 0 0 30 50
LFK 97 76 99 76 / 10 0 20 40
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...Heat Advisory until 7 PM CDT Sunday for ARZ050-051-059>061-
070>073.
LA...Excessive Heat Warning until 7 PM CDT Sunday for LAZ001>006-
010>014-017>022.
OK...Heat Advisory until 7 PM CDT Sunday for OKZ077.
TX...Heat Advisory until 7 PM CDT Sunday for TXZ096-097-108>112-
124>126-136>138-149>153-165>167.
&&
$$
CN/44
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