Alert archive / Oklahoma / Mesoscale Discussions in 2009

Mesoscale Discussion 649

April 30, 200921 counties in Oklahoma

The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2009, 11:41 PM CDT for 21 counties in Oklahoma. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: Apr 30, 2009, 11:41 PM CDT (04:41 UTC)
Expired: May 1, 2009, 12:45 AM CDT
In force: 64 min
Issued by: the Storm Prediction Center

All 21 counties

Beckham County, OK, Blaine County, OK, Caddo County, OK, Canadian County, OK, Cleveland County, OK, Custer County, OK, Dewey County, OK, Ellis County, OK, Grady County, OK, Kingfisher County, OK, Lincoln County, OK, Logan County, OK, Major County, OK, McClain County, OK, Oklahoma County, OK, Payne County, OK, Pottawatomie County, OK, Roger Mills County, OK, Seminole County, OK, Washita County, OK, Woodward County, OK

The radar

The Norman radar (KTLX), 69 km from the middle of the area, began a volume at 04:41 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.

Severe Thunderstorm Watch 219May 1, 12:45 AM CDT

The nearest sounding before it

Norman, OK (KOUN), launched 00:00Z, 4.7 hours before the alert went out and 67 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: 1831 J/kg
Mixed-layer CIN: -60 J/kg
Mixed-layer LCL: 1271 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 66 m²/s²
0-3 km storm-relative helicity: 197 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 6.5

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 30, 7:54 PM CDT	Severe Thunderstorm Watch	SPC	Beckham, Blaine, Caddo, Canadian, Cleveland, Custer and 15 more	5 hr
May 1, 12:45 AM CDT	Severe Thunderstorm Watch	SPC	Adair, Canadian, Cherokee, Cleveland, Craig, Creek and 29 more	6 hr
May 1, 3:00 AM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Craig, Creek, Delaware, Garfield and 16 more	2 hr
May 1, 6:08 AM CDT	Mesoscale Discussion	SPC	Adair, Alfalfa, Cherokee, Craig, Creek, Delaware and 18 more	67 min
May 1, 7:26 AM CDT	Severe Thunderstorm Watch	SPC	Adair, Cherokee, Cleveland, Creek, Garfield, Grant and 27 more	7 hr
May 1, 10:32 AM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Mayes, Noble, Osage, Pawnee and 5 more	58 min
May 1, 1:22 PM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Cleveland, Creek, Garfield, Grant and 20 more	53 min
May 1, 2:48 PM CDT	Mesoscale Discussion	SPC	Carter, Cotton, Jefferson, Love, Murray	87 min
May 1, 3:09 PM CDT	Tornado Watch	SPC	Atoka, Bryan, Carter, Cleveland, Coal, Comanche and 16 more	7 hr

Nearby

Mesoscale Discussions in Oklahoma, 2009 Every mesoscale discussion in 2009

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.