Alert archive / Oklahoma / Mesoscale Discussions in 2017

Mesoscale Discussion 533

April 21, 201732 counties in Oklahoma; 14 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2017, 3:44 AM CDT for 32 counties in Oklahoma; 14 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 21, 2017, 3:44 AM CDT (08:44 UTC)
Expired
Apr 21, 2017, 5:45 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 46 counties

Beckham County, OK, Blaine County, OK, Caddo County, OK, Canadian County, OK, Carter County, OK, Cleveland County, OK, Comanche County, OK, Cotton County, OK, Custer County, OK, Dewey County, OK, Ellis County, OK, Garvin County, OK, Grady County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Jefferson County, OK, Kingfisher County, OK, Kiowa County, OK, Lincoln County, OK, Logan County, OK, Major County, OK, McClain County, OK, Murray County, OK, Oklahoma County, OK, Payne County, OK, Pontotoc County, OK, Pottawatomie County, OK, Roger Mills County, OK, Stephens County, OK, Tillman County, OK, Washita County, OK, Armstrong County, TX, Carson County, TX, Collingsworth County, TX, Donley County, TX, Gray County, TX, Hansford County, TX, Hemphill County, TX, Hutchinson County, TX, Lipscomb County, TX, Moore County, TX, Ochiltree County, TX, Potter County, TX, Roberts County, TX, Wheeler County, TX

The radar

The Altus AFB radar (KFDR), 100 km from the middle of the area, began a volume at 08:48 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Norman, OK (KOUN), launched 00:00Z, 8.7 hours before the alert went out and 185 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, Norman, OK at 00:00Z on 2017-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Norman, OK at 00:00Z on 2017-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 121 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
909 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
121 m²/s²
0-3 km storm-relative helicity
350 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.6

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 20, 9:33 PM CDTSevere Thunderstorm WatchSPCBeckham, Blaine, Caddo, Canadian, Carter, Cleveland and 20 more7 hr
Apr 20, 11:30 PM CDTMesoscale DiscussionSPCBeckham, Blaine, Caddo, Canadian, Carter, Cleveland and 19 more60 min
Apr 21, 4:20 AM CDTSevere Thunderstorm WatchSPCAlfalfa, Atoka, Beaver, Beckham, Blaine, Bryan and 42 more8 hr
Apr 21, 7:54 AM CDTMesoscale DiscussionSPCAlfalfa, Beckham, Blaine, Caddo, Canadian, Carter and 27 more2 hr
Apr 21, 9:45 AM CDTMesoscale DiscussionSPCAdair, Atoka, Cherokee, Cleveland, Coal, Creek and 23 more2 hr
Apr 21, 10:04 AM CDTSevere Thunderstorm WatchSPCAdair, Cherokee, Choctaw, Creek, Haskell, Latimer and 11 more5 hr
Apr 21, 1:12 PM CDTMesoscale DiscussionSPCLeFlore93 min
Apr 21, 3:09 PM CDTMesoscale DiscussionSPCAtoka, Bryan, Carter, Choctaw, Coal, Jefferson and 5 more2 hr
Apr 21, 3:54 PM CDTMesoscale DiscussionSPCAdair, Cherokee, Coal, Creek, Delaware, Haskell and 17 more66 min
Apr 21, 4:40 PM CDTTornado WatchSPCAtoka, Bryan, Carter, Choctaw, Coal, Haskell and 11 more8 hr
Apr 21, 1:07 AM CDTMesoscale DiscussionSPCCooke, Denton, Grayson, Montague, Wise113 min

Nearby

Mesoscale Discussions in Oklahoma, 2017Mesoscale Discussions in Texas, 2017Every mesoscale discussion in 2017

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.