Special Weather Statement, NWS Shreveport, LA

Area Forecast Discussion
National Weather Service Shreveport LA
731 PM CDT Sun May 9 2021

.AVIATION...

Areas of convection will continue to affect the terminals s of
I-30 this evening into the overnight hours. Low cigs/vsbys likely
invof convection. In the wake of a swd-movg cold front later
tonight into early Monday morning, MVFR/IFR cigs to develop and
remain across most sites through the end of the pd. /12/

&&

PREV DISCUSSION... /issued 256 PM CDT Sun May 9 2021/

SHORT TERM.../Tonight through Monday Night/

Severe weather conditions wind down tonight, however, the main
hazard will then evolve into a heavy rain threat, especially south
of the I-20 corridor. With the frontal boundary slowing down as it
approaches our southern zones, the potential for isolated flash
flooding increases as it focuses moisture over Deep East Texas
into Central Louisiana. That moisture includes well above average
precipitable water values of at least 1.5 inches or more. What
limits the magnitude of the flash flooding threat for tonight
involves the eventual progression of the frontal boundary, which
may prevent storms from training over the same areas. The WPC has
a Day 1 slight risk for excessive rainfall of 2 to 3 inches (with
isolated higher amounts possible) over most of the Ark-La-Tex with
the latest update trending the risk area further south. While the
flash flooding threat for tonight remains isolated, all rainfall
from today reduces soil capacity for the additional rainfall
arriving tomorrow and Tuesday, boosting the likelihood of Flash
Flood Watch issuance after tonight.

As the frontal boundary will linger over our area tonight, this
bisection of air masses will produce a gradient of low
temperatures ranging from the lower-50s north of the I-30 corridor
to the upper-60s in Deep East Texas and Central Louisiana. This
gradient of temperatures also continues into tomorrow with
precipitation moderating the diurnal curve to a range of highs in
the upper-60s to upper-70s. This second round of precipitation
will develop along the frontal boundary, still lingering near the
I-20 corridor on Monday afternoon, and continue through the night
to keep temperatures mostly near average in the mid-50s to low-
60s. /16/

LONG TERM.../Tuesday through Sunday/

By Tuesday morning, the cold front should have slipped S of the
region into SE TX/S LA, although the cool post-frontal air mass will
remain shallow, with periods of overrunning becoming enhanced by
weak perturbations aloft that will begin to eject NE across Cntrl
and E TX ahead of shortwave troughing that will shift E into the
Cntrl Plains and dampen. H850 troughing is progged to be over
portions of SE Ok/Nrn sections of SW AR to start the period, but
should begin to lift back N away from the area in response to the
increased overrunning, with weak shortwave perturbations in the WSW
flow aloft yielding an increase in slightly elevated convection as
it begins to spread ENE into much of the region. Given some
uncertainties with regards to timing of the convection, have delayed
categorical pops until the afternoon for much of the area, although
overall intensity and amounts are still in question given the lack
of a more significant LLJ and low level focusing mechanism. However,
should rainfall rates be high enough especially over areas that
could receive locally heavy rainfall this afternoon and evening from
the deeper convection ahead of the approaching cold front, then
localized flooding will be a possibility over those areas,
especially as the rains continue into Tuesday night and Wednesday
morning.

A second shortwave trough translating ESE out of the Rockies and
into the Plains Wednesday should amplify slightly enough such that a
deep wedge of drier air will begin to advect SE through the region,
thus diminishing the convection from NW to SE during the day. Post-
frontal stratus will linger though, maintaining abnormally cool
temps until a warming trend commences Thursday as cigs lift and
begin to scatter out during the afternoon especially over portions
of SW AR/N LA. Sfc ridging remains progged to nose into the region
Thursday as well, as it shifts SE into the Mid-South region Friday,
resulting in a comfortable return of cooler temps and lower RH's.
Mild afternoon temps and lower RH's should persist to round out the
new work week, before a warming trend commences Saturday as SSE low
level winds return on the backside of the retreating sfc ridge as it
enters the TN Valley/Gulf States. There is better model consensus
today in regards to flat ridging aloft building over the Srn Plains
next weekend, despite the presence of potential shortwave energy
dropping SE atop the ridge over OK/AR Saturday. Low level moisture
advection looks to remain too shallow to support even any isolated
convection, and thus have removed pops Saturday across the Nrn and
Wrn zones, although the moisture profile may be a bit deeper Sunday
with the next potential shortwave (per the ECMWF) rounding atop the
ridge along the Red River Valley. Thus, slight chance pops were
retained for E TX/SE OK/adjacent SW AR, as temps return to more
seasonal norms.

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  62  70  58  68 /  70  50  70  90
MLU  61  69  58  69 /  90  50  50  80
DEQ  53  67  53  62 /  10  30  60  70
TXK  55  65  55  63 /  40  30  70  80
ELD  54  66  53  64 /  70  40  60  70
TYR  61  70  58  68 /  40  40  70  90
GGG  62  70  57  68 /  60  50  70  90
LFK  68  80  64  74 /  70  60  50  80

&&

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

12/16/15

Hazardous Weather Outlook
National Weather Service Shreveport LA
1202 PM CDT Sun May 9 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>167-101100-
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-
1202 PM CDT Sun May 9 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...This Afternoon and Tonight...

Showers and thunderstorms will increase this afternoon across the
region, near and ahead of a cold front that will enter Northeast
Texas and Southwest Arkansas. The threat for severe weather will
increase as well for much of the region, with damaging winds,
large hail, and an isolated tornado or two possible. Locally heavy
rainfall will also be possible in the stronger storms, which may
lead to localized flash flooding. These storms should gradually
diminish across East Texas and North Louisiana late this evening
and overnight.

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

As the cold front continues to shift south into Lower East Texas
and North Louisiana south of the Interstate 20 corridor late
tonight, it should stall Monday over portions of Deep East Texas
and Central Louisiana, with overrunning atop the shallow front
contributing to additional periods of showers and a few
thunderstorms across the region through Wednesday. Periods of
moderate to heavy rainfall will be possible, especially Tuesday
and Tuesday night, which may lead to localized flooding. Isolated
strong storms also can not be ruled out, with hail and locally
gusty winds possible.

.SPOTTER INFORMATION STATEMENT...

Activation of emergency management personnel...amateur radio
operators...and storm spotters will be needed this afternoon and
evening.

15

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
742 PM CDT SUN MAY 9 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0710 PM     TSTM WND DMG     LUFKIN                  31.34N 94.73W
05/09/2021                   ANGELINA           TX   DEPT OF HIGHWAYS

            DOWNED TREES REPORTED ON FM 2497, FM 328, FM
            1669, SH 103 WEST, FM 1475, FM 706 AT
            CRAWFORD CREEK AND FM 2109. CREWS ARE
            RESPONDING TO DOWNED TREES IN SEVERAL
            LOCATIONS IN ANGELINA COUNTY INCLUDING SH
            103 WEST NEAR NEWMAN ROAD, FM 1475 AND US 69
            NORTH FOR FLOODED ROADWAYS. DOWNED TREES
            REPORTED ON FM 1669 AND FM 328.

&&

25

Special Weather Statement
National Weather Service Shreveport LA
805 PM CDT Sun May 9 2021

LAZ018>020-100200-
Winn LA-Natchitoches LA-Grant LA-
805 PM CDT Sun May 9 2021

...SIGNIFICANT WEATHER ADVISORY FOR GRANT...SOUTHEASTERN NATCHITOCHES
AND SOUTH CENTRAL WINN PARISHES UNTIL 900 PM CDT...

At 805 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles northeast of Montgomery to near
Flatwoods. Movement was east at 20 mph.

Strong winds of 40 to 50 will be possible with these storms.

Locations impacted include...
Ball, Colfax, Pollock, Dry Prong, Lake Iatt, Aloha, Williana and
Bentley.

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.

&&

A Severe Thunderstorm Watch remains in effect until 100 AM CDT for
north central and northwestern Louisiana.

LAT...LON 3141 9267 3140 9268 3140 9270 3142 9268
      3143 9269 3145 9268 3144 9270 3145 9271
      3147 9271 3147 9269 3152 9272 3142 9285
      3142 9287 3179 9282 3179 9240 3143 9243
      3139 9266
TIME...MOT...LOC 0104Z 282DEG 16KT 3172 9277 3140 9279

15

Special Weather Statement
National Weather Service Shreveport LA
814 PM CDT Sun May 9 2021

ARZ072-073-LAZ004-006-100215-
Union AR-Columbia AR-Union LA-Claiborne LA-
814 PM CDT Sun May 9 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN UNION AND SOUTHEASTERN
COLUMBIA COUNTIES...UNION AND NORTHERN CLAIBORNE PARISHES UNTIL 915
PM CDT...

At 814 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from Huttig to near Haynesville. Movement was
southeast at 25 mph.

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

Locations impacted include...
Huttig, Junction City, Farmerville, Haynesville, Bernice, Atlanta,
Cooley, Marion, Lisbon, Felsenthal, Spearsville, Lillie, Hew Hope,
Antioch, Aurelle, Oakland, Linville, Haile, Taylorville and
Summerfield.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

A Severe Thunderstorm Watch remains in effect until 900 PM CDT for
south central and southwestern Arkansas...and north central and
northwestern Louisiana.

LAT...LON 3277 9297 3308 9329 3310 9214 3307 9213
      3307 9211 3303 9211 3303 9209 3301 9207
      3298 9208 3297 9207 3297 9208 3292 9207
      3287 9208 3284 9206 3282 9207 3279 9205
TIME...MOT...LOC 0114Z 311DEG 20KT 3306 9217 3304 9315

33

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SHREVEPORT LA
815 PM CDT SUN MAY 9 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0650 PM     FLASH FLOOD      LUFKIN                  31.34N 94.73W
05/09/2021                   ANGELINA           TX   DEPT OF HIGHWAYS

            CORRECTS TIME FOR PREVIOUS FLASH FLOOD
            REPORT FROM LUFKIN. HIGH WATER REPORTED ON
            FM 2497, FM 328, FM 1669, SH 103 WEST, FM
            1475, FM 706 AT CRAWFORD CREEK AND FM 2109.
            SH 103 WEST NEAR NEWMAN ROAD, FM 1475 AND US
            69 NORTH FOR FLOODED ROADWAYS. SEVERAL ROADS
            IN LUFKIN ARE REPORTED FLOODED WITH REPORTS
            OF ENTRAPMENT IN SOME AREAS OF HIGH WATER.
            TRAFFIC IS HEAVY ON SL 287 SOUTH NEAR THE US
            59 FLYOVER AND SOME VEHICLES REPORTEDLY ARE
            TRAVELING THE WRONG DIRECTION TO AVOID
            FLOODED ROADWAYS.

&&

25

Special Weather Statement
National Weather Service Shreveport LA
815 PM CDT Sun May 9 2021

LAZ003-004-012-100215-
Bienville LA-Claiborne LA-Webster LA-
815 PM CDT Sun May 9 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN WEBSTER...SOUTHWESTERN
CLAIBORNE AND NORTH CENTRAL BIENVILLE PARISHES UNTIL 915 PM CDT...

At 815 PM CDT, Doppler radar was tracking a strong thunderstorm near
Shongaloo, or 7 miles southeast of Springhill, moving southeast at 35
mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Minden, Homer, Cotton Valley, Gibsland, Sarepta, Shongaloo,
Evergreen, Athens, Mount Lebanon, Leton, Holly Springs, Aycock,
Spring Lake, Lake Clairborne and Ada.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

A Severe Thunderstorm Watch remains in effect until 900 PM CDT for
southwestern Arkansas...and north central and northwestern Louisiana.

LAT...LON 3246 9315 3287 9345 3289 9348 3290 9348
      3290 9347 3292 9347 3302 9336 3302 9325
      3269 9286 3267 9287 3263 9286
TIME...MOT...LOC 0115Z 308DEG 30KT 3293 9336

33