Alert archive / Oklahoma / Mesoscale Discussions in 2013

Mesoscale Discussion 688

May 18, 201320 counties in Oklahoma

The Storm Prediction Center issued this mesoscale discussion at May 18, 2013, 10:44 PM CDT for 20 counties in Oklahoma. It was in force for 31 min.

The area

The outline as issued.

The facts

Issued: May 18, 2013, 10:44 PM CDT (03:44 UTC)
Expired: May 18, 2013, 11:15 PM CDT
In force: 31 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Cleveland County, OK, Creek County, OK, Garvin County, OK, Grady County, OK, Hughes County, OK, Lincoln County, OK, McClain County, OK, Nowata County, OK, Okfuskee County, OK, Oklahoma County, OK, Okmulgee County, OK, Osage County, OK, Pawnee County, OK, Payne County, OK, Pontotoc County, OK, Pottawatomie County, OK, Rogers County, OK, Seminole County, OK, Tulsa County, OK, Washington County, OK

The radar

The Norman radar (KTLX), 45 km from the middle of the area, began a volume at 03:47 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.

The watches that followed

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

Severe Thunderstorm Watch 177May 18, 11:00 PM CDT

The nearest sounding before it

Norman, OK (KOUN), launched 00:00Z, 3.7 hours before the alert went out and 62 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: 3824 J/kg
Mixed-layer CIN: -124 J/kg
Mixed-layer LCL: 1277 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 109 m²/s²
0-3 km storm-relative helicity: 170 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 6.8

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
May 18, 9:03 PM CDT	Mesoscale Discussion	SPC	Alfalfa, Beaver, Beckham, Blaine, Caddo, Canadian and 33 more	57 min
May 18, 11:00 PM CDT	Severe Thunderstorm Watch	SPC	Carter, Cleveland, Coal, Comanche, Cotton, Craig and 24 more	4 hr
May 19, 5:25 AM CDT	Mesoscale Discussion	SPC	Craig, Nowata, Washington	2 hr
May 19, 12:51 PM CDT	Mesoscale Discussion	SPC	Alfalfa, Grant, Kay, Nowata, Washington	114 min
May 19, 1:45 PM CDT	Mesoscale Discussion	SPC	Alfalfa, Blaine, Caddo, Canadian, Carter, Cleveland and 26 more	60 min
May 19, 2:14 PM CDT	Tornado Watch	SPC	Adair, Atoka, Bryan, Caddo, Canadian, Carter and 50 more	9 hr
May 19, 3:27 PM CDT	Mesoscale Discussion	SPC	Alfalfa, Beaver, Ellis, Harper, Woods, Woodward	63 min
May 19, 4:37 PM CDT	Mesoscale Discussion	SPC	Cleveland, Lincoln, Oklahoma, Pottawatomie	53 min
May 19, 5:08 PM CDT	Mesoscale Discussion	SPC	Cleveland, Creek, Lincoln, Oklahoma, Pottawatomie	37 min
May 19, 6:27 PM CDT	Mesoscale Discussion	SPC	Creek, Kay, Lincoln, Noble, Okfuskee, Oklahoma and 5 more	63 min

Nearby

Mesoscale Discussions in Oklahoma, 2013 Every mesoscale discussion in 2013

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.