Alert archive / Oklahoma / Mesoscale Discussions in 2015

Mesoscale Discussion 1815

September 18, 2015Harper County, Sumner County, Kansas; 20 counties in Oklahoma; 5 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Sep 18, 2015, 3:07 PM CDT for Harper County, Sumner County, Kansas; 20 counties in Oklahoma; 5 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Sep 18, 2015, 3:07 PM CDT (20:07 UTC)
Expired: Sep 18, 2015, 5:30 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 27 counties

Harper County, KS, Sumner County, KS, Alfalfa County, OK, Beckham County, OK, Blaine County, OK, Caddo County, OK, Canadian County, OK, Custer County, OK, Dewey County, OK, Garfield County, OK, Grant County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Kingfisher County, OK, Kiowa County, OK, Logan County, OK, Major County, OK, Noble County, OK, Roger Mills County, OK, Washita County, OK, Woods County, OK, Childress County, TX, Collingsworth County, TX, Donley County, TX, Hall County, TX, Wheeler County, TX

The radar

The Altus AFB radar (KFDR), 134 km from the middle of the area, began a volume at 20:10 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

Norman, OK (KOUN), launched 12:00Z, 8.1 hours before the alert went out and 167 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: 310 J/kg
Mixed-layer CIN: -371 J/kg
Mixed-layer LCL: 1468 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 56 m²/s²
0-3 km storm-relative helicity: 58 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Sep 17, 10:12 PM CDT	Mesoscale Discussion	SPC	Atchison, Doniphan	63 min

Nearby

Mesoscale Discussions in Oklahoma, 2015 Mesoscale Discussions in Texas, 2015 Mesoscale Discussions in Kansas, 2015 Every mesoscale discussion in 2015

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.