Alert archive / Oklahoma / Mesoscale Discussions in 2021

Mesoscale Discussion 448

April 28, 20214 counties in Arkansas; 10 counties in Oklahoma; 5 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2021, 9:25 AM CDT for 4 counties in Arkansas; 10 counties in Oklahoma; 5 counties in Texas. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued
Apr 28, 2021, 9:25 AM CDT (14:25 UTC)
Expired
Apr 28, 2021, 10:30 AM CDT
In force
65 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 116

Counties Carroll County, AR, Crawford County, AR, Madison County, AR, Washington County, AR, Atoka County, OK, Bryan County, OK, Coal County, OK, Haskell County, OK, Johnston County, OK, Latimer County, OK, Love County, OK, Marshall County, OK, Pittsburg County, OK, Sequoyah County, OK, Cooke County, TX, Denton County, TX, Grayson County, TX, Parker County, TX, Wise County, TX

The radar

The Norman radar (KTLX), 151 km from the middle of the area, began a volume at 14:26 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

Fort Worth, TX (KFWD), launched 12:00Z, 2.4 hours before the alert went out and 210 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-pSkew-T log-p diagram, Fort Worth, TX at 12:00Z on 2021-04-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 678 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Fort Worth, TX at 12:00Z on 2021-04-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 290 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
678 J/kg
Mixed-layer CIN
-63 J/kg
Mixed-layer LCL
635 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
290 m²/s²
0-3 km storm-relative helicity
394 m²/s²
Significant tornado parameter
1.7
Supercell composite
12.5

Open this sounding in Storm Lab

The text

As transmitted.

818 
ACUS11 KWNS 281426
SWOMCD
SPC MCD 281425 
ARZ000-OKZ000-TXZ000-281530-

Mesoscale Discussion 0448
NWS Storm Prediction Center Norman OK
0925 AM CDT Wed Apr 28 2021

Areas affected...Portions of north-central TX...southern/eastern
OK...and northwestern AR

Concerning...Tornado Watch 116...

Valid 281425Z - 281530Z

The severe weather threat for Tornado Watch 116 continues.

SUMMARY...An isolated severe threat continues this morning, but the
need for additional watch issuance remains unclear.

DISCUSSION...Within a broad precipitation shield, embedded
thunderstorms have shown signs of occasional organization/rotation
this morning from parts of north-central TX into southern/eastern OK
and northwestern AR. Instability remains fairly weak across this
region, with MLCAPE around 500-1000 J/kg downstream of ongoing
convection. Even with this limited instability, the presence of rich
low-level moisture and a 35-45 kt southerly low-level jet may
support continued storm organization with the strongest updrafts.
The overall severe threat has remained rather isolated so far this
morning, and this trend should continue for the next few hours
before potentially increasing again later this afternoon. At this
point, it remains unclear whether another watch issuance will be
needed to replace Tornado Watch 116, which is scheduled to expire at
15Z (10 AM CDT). Regardless, radar trends will continue to be
closely monitored.

..Gleason/Hart.. 04/28/2021

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

ATTN...WFO...TSA...FWD...OUN...

LAT...LON   32719797 33549778 35079617 36349384 36399347 35779374
            32809752 32719797

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 28, 3:01 AM CDTTornado WatchSPCBenton, Carroll, Crawford, Madison, Washington7 hr
Apr 28, 6:35 AM CDTMesoscale DiscussionSPCWashington3 hr
Apr 28, 8:52 AM CDTMesoscale DiscussionSPCBaxter, Boone, Clay, Cleburne, Conway, Craighead and 17 more113 min
Apr 28, 10:56 AM CDTMesoscale DiscussionSPCFulton64 min
Apr 28, 6:01 PM CDTMesoscale DiscussionSPCCrawford, Franklin, Howard, Logan, Montgomery, Polk and 3 more119 min
Apr 27, 8:01 PM CDTMesoscale DiscussionSPCComanche, Cotton, Jefferson, Stephens, Tillman89 min
Apr 27, 8:23 PM CDTSevere Thunderstorm WatchSPCCarter, Cleveland, Comanche, Cotton, Garvin, Jefferson and 10 more7 hr
Apr 27, 10:39 PM CDTMesoscale DiscussionSPCAndrews, Borden, Crane, Dawson, Ector, Howard and 5 more2 hr
Apr 28, 1:38 AM CDTMesoscale DiscussionSPCCallahan, Coke, Coleman, Eastland, Glasscock, Jones and 10 more2 hr
Apr 28, 1:14 PM CDTMesoscale DiscussionSPCBrown, Callahan, Coleman, Comanche, Cooke, Denton and 14 more2 hr
Apr 28, 1:57 PM CDTTornado WatchSPCBrown, Callahan, Coke, Coleman, Comanche, Concho and 16 more9 hr
Apr 28, 2:42 PM CDTMesoscale DiscussionSPCBandera, Blanco, Edwards, Gillespie, Kendall, Kerr and 9 more2 hr
Apr 28, 3:10 PM CDTTornado WatchSPCAtascosa, Bandera, Bexar, Blanco, Comal, Dimmit and 23 more8 hr
Apr 28, 3:40 PM CDTMesoscale DiscussionSPCBrown, Callahan, Coleman, Comanche, Eastland, Runnels and 2 more95 min
Apr 28, 5:41 PM CDTMesoscale DiscussionSPCBandera, Bexar, Frio, Kendall, Kinney, Maverick and 4 more2 hr

Nearby

Mesoscale Discussions in Oklahoma, 2021Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Arkansas, 2021Every 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.