Alert archive / Oklahoma / Mesoscale Discussions in 2012

Mesoscale Discussion 617

April 28, 201210 counties in Oklahoma

The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2012, 10:54 PM CDT for 10 counties in Oklahoma. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 28, 2012, 10:54 PM CDT (03:54 UTC)
Expired: Apr 29, 2012, 1:00 AM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 200

Counties Caddo County, OK, Canadian County, OK, Cleveland County, OK, Comanche County, OK, Cotton County, OK, Grady County, OK, McClain County, OK, Oklahoma County, OK, Stephens County, OK, Tillman County, OK

The radar

The Norman radar (KTLX), 66 km from the middle of the area, began a volume at 03:56 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 00:00Z, 3.9 hours before the alert went out and 51 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: 1947 J/kg
Mixed-layer CIN: -49 J/kg
Mixed-layer LCL: 989 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 144 m²/s²
0-3 km storm-relative helicity: 232 m²/s²
Significant tornado parameter: 2.1
Supercell composite: 7.6

Open this sounding in Storm Lab

The text

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

097 
ACUS11 KWNS 290354
SWOMCD
SPC MCD 290354 
OKZ000-TXZ000-290600-

MESOSCALE DISCUSSION 0617
NWS STORM PREDICTION CENTER NORMAN OK
1054 PM CDT SAT APR 28 2012

AREAS AFFECTED...CNTRL AND WRN OKS INTO NWRN TX

CONCERNING...SEVERE THUNDERSTORM WATCH 200...

VALID 290354Z - 290600Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 200
CONTINUES.

SCATTERED SUPERCELLS EXIST FROM NWRN TX INTO CNTRL OK. TWO CELLS
WERE N OF THE SURFACE BOUNDARY OVER CNTRL OK...BUT WERE MOVING
MOSTLY IN AN EWD DIRECTION. ALTHOUGH CELLS ARE FIGHTING SOME CAPPING
AND CIN...FAVORABLE WIND PROFILES ARE LIKELY TO KEEP THESE CELLS
GOING FOR A WHILE. AS THEY APPROACH THE SURFACE FRONT...THEY WILL
ENCOUNTER SLIGHTER WARMER AND MOISTER LOW LEVEL AIR MASS...WHICH
COULD HELP IN VERTICAL ACCELERATIONS DOWN LOW. THIS...ALONG WITH
MORE THAN ADEQUATE LOW LEVEL SHEAR...COULD RESULT IN A BRIEF
TORNADO.

TO THE S...LARGE HAIL WAS THE MAIN THREAT OVER NWRN TX WHERE LOW
LEVEL T/TD SPREADS WERE LARGER. SOME OF THESE CELLS WERE LEFT
MOVING...AND WILL EXIT THE WATCH INTO PORTIONS OF THE ERN TX
PANHANDLE...BUT AN ADDITIONAL WATCH IS NOT EXPECTED AT THIS TIME.

..JEWELL.. 04/29/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...OUN...

LAT...LON   35599794 35759755 35719703 35529686 35369697 34959722
            34029826 34029875 34249912 34599904 35379845 35599794

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 28, 10:36 PM CDT	Tornado Watch	SPC	Caddo, Canadian, Cleveland, Comanche, Cotton, Garvin and 11 more	3 hr
Apr 28, 11:52 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Cherokee, Craig, Creek, Delaware, McIntosh and 13 more	5 hr
Apr 29, 1:37 AM CDT	Mesoscale Discussion	SPC	Alfalfa, Beckham, Blaine, Custer, Dewey, Garfield and 8 more	23 min
Apr 29, 1:53 AM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Craig, Creek, Delaware, Kay and 12 more	2 hr
Apr 29, 3:13 AM CDT	Mesoscale Discussion	SPC	Beckham, Custer, Dewey, Roger Mills	92 min
Apr 29, 2:22 PM CDT	Mesoscale Discussion	SPC	Cimarron	113 min
Apr 29, 5:10 PM CDT	Severe Thunderstorm Watch	SPC	Beaver, Cimarron, Harper, Texas	8 hr
Apr 29, 5:51 PM CDT	Mesoscale Discussion	SPC	Alfalfa, Canadian, Craig, Creek, Garfield, Grant and 17 more	2 hr

Nearby

Mesoscale Discussions in Oklahoma, 2012 Every mesoscale discussion in 2012

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.