Mesoscale Discussion 406

Issued

Apr 23, 2021, 12:43 PM CDT (17:43 UTC)

Expired

Apr 23, 2021, 3:15 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch likely

Chance of a watch

80%

Counties Baylor County, TX, Childress County, TX, Collingsworth County, TX, Cottle County, TX, Foard County, TX, Hall County, TX, Hardeman County, TX, Knox County, TX

The Altus AFB radar (KFDR), 99 km from the middle of the area, began a volume at 17:47 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.

• Tornado Watch 100Apr 23, 3:15 PM CDT

824 
ACUS11 KWNS 231743
SWOMCD
SPC MCD 231743 
TXZ000-OKZ000-232015-

Mesoscale Discussion 0406
NWS Storm Prediction Center Norman OK
1243 PM CDT Fri Apr 23 2021

Areas affected...southeast TX Panhandle...western north-central
TX...far southwest OK

Concerning...Severe potential...Watch likely 

Valid 231743Z - 232015Z

Probability of Watch Issuance...80 percent

SUMMARY...Convective initiation is expected during the 230-400 pm
period with storms subsequently maturing and becoming severe.  A
large to giant hail risk (1 to 3+ inches in diameter) may accompany
the stronger storms, especially late this afternoon; coincident in
general timing with the peaking of a tornado threat.  Additional
storm development and upscale growth will facilitate the transition
to severe gusts becoming more common during the evening across
south-central and central OK.

DISCUSSION...Visible satellite imagery shows a cumulus field over
the TX Low Rolling Plains east of the Caprock escarpment, where a
dryline is becoming better defined from north to south.  Surface
temperatures as of 1230 pm have warmed into the low 70s in Dickens
County to the east of Lubbock and the northwestern rim of low 60s
dewpoints arcs from 50 mi west of Abilene northeastward to near the
Fredrick, OK WSR-88D location in southwest OK.  

Forecast soundings from 200 pm to 400 pm show the warming of the
boundary layer to the east of the dryline at C11 (Seymour, TX) from
the upper 60s to the mid 70s during the timeframe.  As a result of
the warming, convective inhibition is essentially eroded.  The
strengthening large-scale ascent associated with the approaching
mid-level trough, will likely yield storms developing by mid
afternoon across western north-central TX into far southwest OK. 
Strong effective shear and 2500-3000 J/kg MLCAPE will favor
supercells with the stronger/persistent updrafts.  Large to giant
hail may occur and possibly a tornado despite low-level shear
relatively limited.  The transition to upscale growth in the form of
a cluster and eventual band is expected this evening as the storms
move east across south-central and central OK.

..Smith/Hart.. 04/23/2021

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

ATTN...WFO...OUN...SJT...LUB...AMA...

LAT...LON   34390071 34950054 35010007 33929916 33399917 33139956
            33400007 34390071

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.