Severe Thunderstorm Warning 209, NWS Shreveport, LA

Area Forecast Discussion
National Weather Service Shreveport LA
647 PM CDT Tue May 26 2020

.AVIATION...
Early evening convection to gradually diminish by 27/02Z with the
loss of daytime heating. Surface high pressure across the region
to allow for light and variable winds overnight. Could see tempo
MVFR ceilings across area terminals around daybreak, clearing by
27/14Z. Otherwise west winds to increase to near 10 knots on
Wednesday afternoon. /05/

&&

.PREV DISCUSSION... /issued 313 PM CDT Tue May 26 2020/

SHORT TERM.../Tonight through Wednesday Night/

As expected, the drier and stable air has won out this afternoon
across much of the region, with the afternoon water vapor imagery
indicating additional drier air entraining ENE into the Wrn half
of the area ahead of the now closed upper low centered over NW
TX/SW OK. However, diurnal heating has contributed to some
instability this afternoon across portions of SE TX, where
isolated convection has developed along a weak shortwave spoke
around the center of the closed low. The instability axis has
begun to work N into E TX/Wrn LA this afternoon, with the
afternoon visible satellite imagery indicating a bit of an
agitated cu field across E TX/SE OK/SW AR, with the 12Z CAMS
suggesting some isolated to scattered convection developing by
late afternoon/early evening as it drifts E into SW AR/N LA. Have
lowered pops to low to mid chance over these areas, although bndry
lyr stabilization should allow for any convection to mostly
diminish by mid to late evening. Did maintain low chance pops late
tonight across the Nrn and Ern zones to account for the potential
for any isolated redevelopment over these areas.

Given the dry air entrainment and lack of concentrated forcing E
of the closed low, have cancelled the Flash Flood Watch for NE
TX/SE OK/SW AR with the afternoon forecast package. Some diurnal
redevelopment will be possible near the center of the low as it
drifts E into Ern OK/far NE TX/Wrn AR Wednesday, but any heavy
rainfall threat should be brief and localized. Slightly below
normal temps should continue Wednesday over much of the area given
the cloud shield, with sct convection possible especially over the
Nrn half of the area with afternoon heating. Have mentioned mid
and high chance pops N of I-20, although the short term progs and
CAMS are hinted at one or more clusters of convection developing
over Wcntrl TX into the Hill Country, as another shortwave
rounding the upper low helps to initiate convection along an area
of focused low level convergence. This potential MCS is progged to
shift ESE into SE TX Wednesday night, with some of this convection
(albeit in a much weaker state) possibly spreading E into the
region late. Thus, have concentrated mid and high chance pops over
the region, as the center of the low begins to drift E into SW AR
Thursday morning.

15

LONG TERM.../Thursday through Monday Night/

Starting 12z Thursday...As we begin the long term period the pattern
will feature a broad closed upper-level low centered over eastern
Oklahoma and western Arkansas with our region on the southern
peripheral of the low. Meanwhile, upper-level ridging will continue
to build over the southwest CONUS. The closed off low will slowly
meander to the east through the day Thursday and into Friday. In
addition, a few disturbances are expected to move through the region
on Thursday, so will need to leave some PoPs in through the day
Thursday and Thursday night. Models are in some disagreement on how
quickly the precipitation exits the area, with the ECMWF keeping
some lingering showers and thunderstorms into Friday morning.
Overall consensus has storms exiting the area by 06z Friday.

The aforementioned closed low will continue to push east and out of
the area through the day Friday. Earlier model runs have shown some
lingering precipitation through the day Friday, but have taken those
chances out with this forecast package. The upper-level ridge will
continue to build into the Four Corners Region through the day
Friday. This ridge will slowly build east and into our area early
Sunday morning. Heading into next week, models are showing hints of
an "Omega Blocking" pattern setting up. With our area being under
the upper-level high, our area should see warming temperatures and a
"lack" of precipitation for the most part. /33/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  63  81  63  81 /  30  30  50  40
MLU  65  83  64  82 /  40  40  50  40
DEQ  60  77  58  79 /  30  50  40  40
TXK  62  78  61  78 /  30  50  50  40
ELD  62  81  61  80 /  40  50  50  50
TYR  60  81  62  81 /  10  30  50  30
GGG  61  81  61  81 /  20  30  50  40
LFK  62  86  63  84 /  20  20  50  40

&&

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

05/15

Hazardous Weather Outlook
National Weather Service Shreveport LA
158 PM CDT Tue May 26 2020

ARZ050-051-059>061-070-071-OKZ077-TXZ096-097-109-111-112-271900-
Sevier-Howard-Little River-Hempstead-Nevada-Miller-Lafayette-
McCurtain-Red River-Bowie-Titus-Morris-Cass-
158 PM CDT Tue May 26 2020

This Hazardous Weather Outlook is for portions of southwest
Arkansas, southeast Oklahoma and northeast Texas.

.DAY ONE...This Afternoon and Tonight...

A Flash Flood Watch is in effect through tonight.

Thunderstorms will increase in coverage this afternoon as another
upper level disturbance moves into the region. A couple of
isolated strong thunderstorms could produce gusty winds and
moderate to heavy rainfall. Any additional heavy rainfall could
lead to flash flooding.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday...

A Flash Flood Watch is in effect until 7 PM CDT Wednesday
evening.

Thunderstorms will remain in the forecast through end of the work
week as a closed low meanders near the region. An isolated strong
to severe thunderstorm cannot be ruled out, but widespread severe
weather is not anticipated. However, more rainfall could lead to
a renewed threat for flash flooding.

.SPOTTER INFORMATION STATEMENT...

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

ARZ072-073-LAZ001>006-010>014-017>022-TXZ108-110-124>126-136>138-
149>153-165>167-271900-
Columbia-Union-Caddo-Bossier-Webster-Claiborne-Lincoln-De Soto-
Red River-Bienville-Jackson-Ouachita-Sabine-Natchitoches-Winn-
Grant-Caldwell-La Salle-Franklin-Camp-Wood-Upshur-Marion-Smith-
Gregg-Harrison-Cherokee-Rusk-Panola-Nacogdoches-Shelby-Angelina-
San Augustine-
158 PM CDT Tue May 26 2020

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

.DAY ONE...This Afternoon and Tonight...

Thunderstorms will increase in coverage this afternoon as another
upper level disturbance moves into the region. A couple of
isolated strong thunderstorms could produce gusty winds and
moderate to heavy rainfall, which could lead to some localized
flooding.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday...

Thunderstorms will remain in the forecast through end of the work
week as a closed low meanders near the region. An isolated strong
to severe thunderstorm cannot be ruled out, but widespread severe
weather is not anticipated. However, more rainfall could lead to
localized flooding.

.SPOTTER INFORMATION STATEMENT...

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

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