Alert archive / Oklahoma / Mesoscale Discussions in 2008

Mesoscale Discussion 679

April 21, 200815 counties in Oklahoma

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2008, 7:34 PM CDT for 15 counties in Oklahoma. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Apr 21, 2008, 7:34 PM CDT (00:34 UTC)
Expired: Apr 21, 2008, 9:00 PM CDT
In force: 86 min
Issued by: the Storm Prediction Center

Counties Carter County, OK, Cleveland County, OK, Creek County, OK, Garfield County, OK, Garvin County, OK, Kingfisher County, OK, Lincoln County, OK, Logan County, OK, McClain County, OK, Murray County, OK, Oklahoma County, OK, Payne County, OK, Pontotoc County, OK, Pottawatomie County, OK, Seminole County, OK

The radar

The Norman radar (KTLX), 32 km from the middle of the area, began a volume at 00:35 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.

Tornado Watch 212Apr 21, 9:00 PM CDT

The nearest sounding before it

Lamont, OK (KLMN), launched 00:00Z, 0.6 hours before the alert went out and 165 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: 1716 J/kg
Mixed-layer CIN: -20 J/kg
Mixed-layer LCL: 1734 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 18 m²/s²
0-3 km storm-relative helicity: 169 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 6.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 21, 7:03 PM CDT	Severe Thunderstorm Watch	SPC	Garfield, Grant, Kay, Noble, Osage, Pawnee and 1 more	7 hr
Apr 21, 8:56 PM CDT	Tornado Watch	SPC	Carter, Cleveland, Coal, Creek, Garvin, Hughes and 11 more	5 hr
Apr 21, 10:29 PM CDT	Mesoscale Discussion	SPC	Carter, Cleveland, Coal, Creek, Garvin, Hughes and 11 more	91 min
Apr 21, 10:38 PM CDT	Mesoscale Discussion	SPC	Garfield, Grant, Kay, Noble, Osage, Pawnee and 1 more	2 hr
Apr 22, 7:42 AM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Delaware	63 min
Apr 22, 7:49 AM CDT	Severe Thunderstorm Watch	SPC	Adair, Cherokee, Craig, Delaware, Mayes, Ottawa and 1 more	6 hr
Apr 22, 10:12 AM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Delaware, Haskell, Latimer, LeFlore and 5 more	93 min
Apr 22, 12:16 PM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Delaware, Haskell, LeFlore, Sequoyah	89 min
Apr 22, 2:06 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Atoka, Bryan, Carter, Cherokee, Choctaw and 31 more	7 hr
Apr 22, 2:33 PM CDT	Severe Thunderstorm Watch	SPC	McCurtain	6 hr
Apr 22, 3:30 PM CDT	Mesoscale Discussion	SPC	Adair, Atoka, Carter, Cherokee, Cleveland, Coal and 24 more	90 min
Apr 22, 6:51 PM CDT	Mesoscale Discussion	SPC	Adair, Carter, Cherokee, Coal, Delaware, Garvin and 17 more	114 min

Nearby

Mesoscale Discussions in Oklahoma, 2008 Every mesoscale discussion in 2008

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.