Mesoscale Discussion 672

Issued

May 18, 2021, 1:57 PM CDT (18:57 UTC)

Expired

May 18, 2021, 4:30 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

Counties Bailey County, TX, Castro County, TX, Deaf Smith County, TX, Parmer County, TX, Randall County, TX, Swisher County, TX

The Cannon AFB radar (KFDX), 87 km from the middle of the area, began a volume at 19:02 UTC, the scan nearest the moment this went out.

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254 
ACUS11 KWNS 181857
SWOMCD
SPC MCD 181857 
TXZ000-NMZ000-182130-

Mesoscale Discussion 0672
NWS Storm Prediction Center Norman OK
0157 PM CDT Tue May 18 2021

Areas affected...Parts of east central New Mexico into the Texas
Panhandle

Concerning...Severe potential...Watch unlikely 

Valid 181857Z - 182130Z

Probability of Watch Issuance...20 percent

SUMMARY...Slowly intensifying storms are possible near and southwest
through south of the Amarillo, TX vicinity through 3-5 PM CDT.  Some
of these may be accompanied by severe hail, and perhaps potential
for a relatively short-lived and weak tornado or two.

DISCUSSION...Thunderstorms have initiated along a low-level
confluence zone, south-southwest through northwest of Clovis, NM. 
This appears where mixed-layer CAPE has become maximized (1000+
J/kg) in response to daytime heating, beneath the leading edge of an
elongated cold core (500 mb temps -16 to -18C) associated with the
remnants of a mid-level low emerging from the Southwest.  This also
appears south-southwest of a convective outflow boundary associated
with a small cluster of thunderstorms now spreading across and north
of the Interstate 40 corridor of the western Texas Panhandle
vicinity.

With continuing insolation, and strengthening differential surface
heating across it, the outflow boundary may become a focus for
enhanced low-level shear and forcing for ascent, providing a
possible focus for stronger thunderstorm development by late
afternoon.  Lower/mid tropospheric wind fields and shear are
otherwise generally modest to weak, but it is possible that
southwesterly flow up to 30 kt, near/above the 500 mb level, could
contribute to sufficient vertical shear for supercell structures
along the boundary.

As a zone of enhanced mid-level forcing for ascent continues
gradually pivoting around the eastern periphery of the mid-level low
through 20-22Z, storms over eastern New Mexico may continue to
increase and intensify while spreading into the Texas Panhandle,
with additional storms also initiating along the outflow boundary. 
A few of these storms may eventually pose a risk for severe hail,
with perhaps some developing potential for generally
weak/short-lived tornadoes.

..Kerr/Guyer.. 05/18/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LUB...AMA...MAF...ABQ...

LAT...LON   33950270 33460314 33730353 34560328 35100292 35130253
            35320191 34420172 33950270

Mesoscale Discussions in Texas, 2021Every mesoscale discussion in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.