Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 436

April 27, 2021Foard County, Knox County, Wilbarger County, Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2021, 3:30 PM CDT for Foard County, Knox County, Wilbarger County, Texas. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: Apr 27, 2021, 3:30 PM CDT (20:30 UTC)
Expired: Apr 27, 2021, 5:00 PM CDT
In force: 90 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 113

Counties Foard County, TX, Knox County, TX, Wilbarger County, TX

The radar

The Altus AFB radar (KFDR), 93 km from the middle of the area, began a volume at 20:32 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Amarillo Airport, TX (KAMA), launched 12:00Z, 8.5 hours before the alert went out and 228 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 4126 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 96 m²/s²
0-3 km storm-relative helicity: 143 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

931 
ACUS11 KWNS 272030
SWOMCD
SPC MCD 272030 
TXZ000-272200-

Mesoscale Discussion 0436
NWS Storm Prediction Center Norman OK
0330 PM CDT Tue Apr 27 2021

Areas affected...Portions of northwest into western north TX

Concerning...Severe Thunderstorm Watch 113...

Valid 272030Z - 272200Z

The severe weather threat for Severe Thunderstorm Watch 113
continues.

SUMMARY...The greatest near-term severe threat, including the
potential for 2-2.5 inch diameter large hail, should be focused with
a supercell moving eastward.

DISCUSSION...A robust supercell has developed over part of northwest
TX in the past hour or so. This storm has recently turned right, and
is moving generally eastward into western north TX. Mid to upper 60s
surface dewpoints are in place ahead of this activity per recent
surface observations from the West TX Mesonet. The presence of steep
mid-level lapse rates, rich low-level moisture, and surface
temperatures warming into the 80s are all supporting 2000-3000 J/kg
of MUCAPE per latest mesoanalysis estimates. This strong instability
coupled with 50-60 kt of effective bulk shear will likely foster
continued storm intensity and organization with this ongoing
supercell in the short term. Large hail appears likely, and very
large hail upwards of 2-2.5+ inches in diameter may also occur given
the very favorable thermodynamic environment and the presence of a
pronounced TBSS from the KLBB radar. The kinematic environment
appears somewhat favorable for a tornado with this supercell, as the
near-surface flow is backed to southeasterly. However, the low-level
wind profile from KDYX/KFDR is not overly strong, and 0-1 km SRH
around 100 m2/s2 will probably support just a brief/isolated tornado
threat in the short term. Depending on the continued eastward
movement of this supercell, a small eastward extension of Severe
Thunderstorm Watch 113 may be needed for a part of western north TX
in the next hour or two.

..Gleason.. 04/27/2021

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

ATTN...WFO...OUN...LUB...

LAT...LON   33830039 34050029 34249996 34179892 33809888 33599937
            33630033 33830039

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 27, 1:17 PM CDT	Mesoscale Discussion	SPC	Childress, Collingsworth, Cottle, Crosby, Dickens, Foard and 9 more	118 min
Apr 27, 1:57 PM CDT	Severe Thunderstorm Watch	SPC	Archer, Baylor, Childress, Clay, Collingsworth, Cottle and 14 more	7 hr
Apr 27, 5:52 PM CDT	Mesoscale Discussion	SPC	Baylor, Dickens, Foard, Hardeman, Kent, King and 5 more	113 min

Nearby

Mesoscale Discussions in Texas, 2021 Every mesoscale discussion in 2021

Sources

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.