Special Weather Statement, NWS Shreveport, LA

Area Forecast Discussion
National Weather Service Shreveport LA
1000 PM CDT Sun Aug 1 2021

.UPDATE...

Our 00Z sounding earlier this evening revealed a fairly unstable
atmosphere in place just ahead of a slowly advancing cold front.
As a result, what was just isolated to widely scattered shwrs and
tstms earlier this afternoon have become more numerous across the
region this evening. Expect this trend to continue overnight even
with the loss of heating as the cold front continues to slowly sag
south of I-20 through early Monday morning. For this update, minor
changes were made to PoPs to carry just chance wording through 06Z
with increasing coverage likely thereafter. Temperatures and other
elements appear to be on track so no additional changes were made.
As far as any severe threat is concerned, the Marginal Risk which
had been advertised earlier by the SPC has been dropped. However,
still cannot rule out some stronger wind gusts near 35 knots with
the numerous outflow boundaries that continue to generate new tstm
development ahead of the front. In addition, some small hail could
also occur with some of the stronger storms along with heavy rain,
which could result in localized flooding in poor drainage areas.
Finally, all previous heat headlines have also been dropped as the
Heat Advisory and Excessive Heat Warning were both allowed to
expire on time at 7PM CDT.

/19/

&&

.PREV DISCUSSION... /issued 735 PM CDT Sun Aug 1 2021/

AVIATION...

For the 02/00Z TAF period, VFR conditions are currently observed
at all terminals to begin the period, but that will be changing as
a cold front transitions southward overnight through Monday. Shwrs
and tstms will become more numerous as the TAF period progresses,
resulting in rapidly deteriorating conditions with MVFR/IFR cigs
and vsbys expected through much of the period. Sfc winds will be
generally light and variable ahead of the frontal boundary except
for gusty winds in areas of pre-frontal convection, then gradually
veer N/NW with fropa before ending the period more from the NE.
Speeds will generally range from 5-10 kts on average with higher
speeds and gusts reserved for areas invof of stronger convection.

/19/

PREV DISCUSSION... /issued 154 PM CDT Sun Aug 1 2021/

SHORT TERM.../Tonight Through Monday Night/

Fairly active weather pattern in the short term period as a cold
front moves across the region bringing increased rain chances
areawide. Convection already beginning to initiate across the
I-30 corridor as a broad upper-level trough begins to dig south
with the front. Weak deep-layer shear values and strong
instability due to hot surface temperatures will support some
pulse storms that could produce strong or damaging wind gusts and
locally heavy rainfall. Hail, although possible, will struggle to
become a significant hazard due to such warm environmental
temperatures in the lower levels. Speaking of hot temperatures, a
Heat Advisory and Excessive Heat Warning remain in effect across
the region through 7 PM.

Heat headlines to no longer be necessary beyond today due to
increased rain chances and cloud cover as well as replacement
high pressure that will bring overall cooler temperatures to the
region. Overnight lows tonight to fall into the lower to middle
70s as high pressure builds areawide. High temperatures on Monday
to climb into the mid to upper 80s.

Additionally, widespread rain coverage to linger into Monday as
broad upper-trough remains parked across Texas into the Red River
Valley and points northward. Some heavier convection may be
triggered by lingering frontal boundary across deep east Texas
into central Louisiana. /05/

LONG TERM.../Tuesday through Saturday Night/

The forecast period begins with a GFS/ECMWF/Canadian consensus that
at the mid-levels a longwave trough axis will be centered over the
Great Lakes and extending southward across the Tennessee Valley into
the Southeast on Tuesday. Meanwhile, a deep ridge will extend from
the Baja Peninsula into the Intermountain West. Between the two
features, the ArkLaTex will be in a northwesterly mid-level flow
through much of the work week. At the surface, high pressure will be
centered over the Great Lakes and Missouri Valley, extending
southward toward the area as the remnant of a cold front slides
southward of the area on Tuesday. This will make any showers and
storms limited to Deep East Texas and central Louisiana on Tuesday.

High pressure to the north of the area will remain the dominant
surface feature through the remainder of the week, helping suppress
showers and thunderstorms and keep the forecast mostly dry Wednesday
and Thursday. By Friday, a southerly low-level flow will support the
possibility of diurnally driven afternoon seabreeze thunderstorms
across Deep East Texas and central Louisiana.

By next weekend, the models are in fairly good agreement that a mid-
level ridge will build in from the west over Texas on Saturday and
be centered over the ArkLaTex by Saturday night. This pattern will
allow for a return to a fairly typical summertime environment for
central Louisiana and the ArkLaMiss with diurnally driven
thunderstorms expected to develop in the afternoon and diminish by
late evening.

For temperatures, in the wake of the front, temperatures will be
around 5 degrees below normal on Tuesday with highs in the upper 80s
to lower 90s across the area. Temperatures will then progressively
warm a degree or two each day with highs closer to normal seasonal
values by Friday into Saturday with highs in the mid 90s across the
area. /04-Woodrum/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  75  86  72  89 /  70  80  40  20
MLU  74  86  70  88 /  70  90  40  20
DEQ  72  85  68  87 /  70  50  10  10
TXK  74  85  70  88 /  80  60  10  10
ELD  71  84  66  87 /  80  80  20  10
TYR  76  86  71  89 /  70  80  20  10
GGG  74  86  70  87 /  70  80  30  10
LFK  76  88  72  90 /  60  90  60  40

&&

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

19/05/04

Hazardous Weather Outlook
National Weather Service Shreveport LA
941 PM CDT Sun Aug 1 2021

ARZ050-051-059>061-070>073-LAZ001>006-010>014-017>022-OKZ077-
TXZ096-097-108>112-124>126-136>138-149>153-165>167-030245-
Sevier-Howard-Little River-Hempstead-Nevada-Miller-Lafayette-
Columbia-Union-Caddo-Bossier-Webster-Claiborne-Lincoln-De Soto-
Red River-Bienville-Jackson-Ouachita-Sabine-Natchitoches-Winn-
Grant-Caldwell-La Salle-McCurtain-Bowie-Franklin-Titus-Camp-
Morris-Cass-Wood-Upshur-Marion-Smith-Gregg-Harrison-Cherokee-Rusk-
Panola-Nacogdoches-Shelby-Angelina-San Augustine-
941 PM CDT Sun Aug 1 2021

This Hazardous Weather Outlook is for portions of south central
Arkansas, southwest Arkansas, north central Louisiana, northwest
Louisiana, southeast Oklahoma, east Texas and northeast Texas.

.DAY ONE...Tonight...

Scattered showers and thunderstorms will be possible through the
night across much of the area. Strong winds and maybe some small
hail will be possible in the stronger storms. Additionally, heavy
rainfall will be possible which could lead to localized flash
flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday...

Scattered thunderstorms are possible Monday as a cold front
slowly moves south across the area. An isolated severe storm or
two cannot be ruled out during the day Monday, especially south of
Interstate 20. Damaging winds will be the primary threat.

.SPOTTER INFORMATION STATEMENT...

Activation of emergency management personnel...amateur radio
operators...and storm spotters will not be needed.

33

Special Weather Statement
National Weather Service Shreveport LA
909 PM CDT Sun Aug 1 2021

LAZ004-005-020245-
Lincoln LA-Claiborne LA-
909 PM CDT Sun Aug 1 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN CLAIBORNE AND
WESTERN LINCOLN PARISHES UNTIL 945 PM CDT...

At 908 PM CDT, Doppler radar was tracking a strong thunderstorm 8
miles north of Arcadia, or 12 miles southeast of Homer, moving
southeast at 10 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Grambling, Dubach, Simsboro, Lisbon, Corinth, Mount Zion, Unionville
and Aycock.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3246 9279 3253 9288 3259 9288 3258 9296
      3263 9302 3279 9290 3268 9262
TIME...MOT...LOC 0208Z 302DEG 8KT 3268 9289

33

Special Weather Statement
National Weather Service Shreveport LA
920 PM CDT Sun Aug 1 2021

LAZ002-003-020300-
Bossier LA-Webster LA-
920 PM CDT Sun Aug 1 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN WEBSTER AND EAST
CENTRAL BOSSIER PARISHES UNTIL 1000 PM CDT...

At 920 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 8 miles northeast of Eastwood to Haughton.
Movement was east at 10 mph.

Half inch hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Haughton, Doyline, Dixie Inn, Eastwood, Princeton, Noles Landing,
Lake Bistineau North, Fillmore, Bellevue and Couchwood.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3280 9334 3243 9331 3246 9352 3269 9357
TIME...MOT...LOC 0220Z 248DEG 8KT 3267 9351 3250 9349

33

Special Weather Statement
National Weather Service Shreveport LA
938 PM CDT Sun Aug 1 2021

ARZ072-LAZ003-020315-
Columbia AR-Webster LA-
938 PM CDT Sun Aug 1 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN COLUMBIA COUNTY IN
SOUTHWESTERN ARKANSAS AND NORTH CENTRAL WEBSTER PARISHES UNTIL 1015
PM CDT...

At 937 PM CDT, Doppler radar was tracking a strong thunderstorm near
Welcome, or near Springhill, moving southeast at 10 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Springhill, Cullen, Taylor, Shongaloo, Welcome, Horsehead and
Walkerville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3307 9318 3288 9338 3302 9349 3309 9349
      3317 9342
TIME...MOT...LOC 0237Z 310DEG 9KT 3306 9342

33

Special Weather Statement
National Weather Service Shreveport LA
1002 PM CDT Sun Aug 1 2021

LAZ003-004-012-020345-
Bienville LA-Claiborne LA-Webster LA-
1002 PM CDT Sun Aug 1 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN WEBSTER...
SOUTHWESTERN CLAIBORNE AND NORTH CENTRAL BIENVILLE PARISHES UNTIL
1045 PM CDT...

At 1002 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 6 miles northwest of Minden to near Doyline.
Movement was east at 15 mph.

Half inch hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Minden, Sibley, Doyline, Dubberly, Dixie Inn, Heflin, Gilark, Noles
Landing, Holly Springs, Ogden, Couchwood and Ada.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3278 9314 3242 9314 3248 9344 3276 9341
TIME...MOT...LOC 0302Z 254DEG 11KT 3269 9335 3254 9337

33

Special Weather Statement
National Weather Service Shreveport LA
1031 PM CDT Sun Aug 1 2021

ARZ072-073-LAZ003-004-020415-
Union AR-Columbia AR-Claiborne LA-Webster LA-
1031 PM CDT Sun Aug 1 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN UNION AND
SOUTHEASTERN COLUMBIA COUNTIES...NORTHWESTERN WEBSTER AND
NORTHWESTERN CLAIBORNE PARISHES UNTIL 1115 PM CDT...

At 1031 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Haynesville to near Cotton Valley.
Movement was east at 20 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Homer, Haynesville, Cotton Valley, Shongaloo, Evergreen, Leton and
Couchwood.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3304 9272 3276 9308 3273 9345 3276 9345
      3277 9347 3278 9347 3306 9321
TIME...MOT...LOC 0331Z 271DEG 16KT 3301 9318 3274 9346

33

Special Weather Statement
National Weather Service Shreveport LA
1043 PM CDT Sun Aug 1 2021

LAZ001-TXZ138-020430-
Caddo LA-Harrison TX-
1043 PM CDT Sun Aug 1 2021

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL CADDO PARISH IN
NORTHWESTERN LOUISIANA AND SOUTHEASTERN HARRISON COUNTIES UNTIL 1130
PM CDT...

At 1043 PM CDT, Doppler radar was tracking a strong thunderstorm near
Marshall, moving east at 25 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Marshall, Greenwood, Waskom, Mooringsport, Karnack, Scottsville,
Jonesville, Caddo Lake, Bethany and Leigh.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3263 9436 3269 9409 3269 9405 3270 9404
      3272 9396 3238 9395 3245 9435
TIME...MOT...LOC 0343Z 268DEG 22KT 3255 9427

33