Alert archive / South Dakota / Mesoscale Discussions in 2011

Mesoscale Discussion 707

May 9, 2011Cherry County, Nebraska; 14 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at May 9, 2011, 10:17 PM MDT for Cherry County, Nebraska; 14 counties in South Dakota. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: May 9, 2011, 10:17 PM MDT (04:17 UTC)
Expired: May 9, 2011, 11:15 PM MDT
In force: 58 min
Issued by: the Storm Prediction Center

Counties Cherry County, NE, Bennett County, SD, Butte County, SD, Corson County, SD, Haakon County, SD, Harding County, SD, Jackson County, SD, Jones County, SD, Meade County, SD, Mellette County, SD, Oglala Lakota County, SD, Pennington County, SD, Perkins County, SD, Todd County, SD, Ziebach County, SD

The radar

The Rapid City radar (KUDX), 60 km from the middle of the area, began a volume at 04:17 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

Rapid City, SD (KUNR), launched 00:00Z, 4.3 hours before the alert went out and 60 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: 231 J/kg
Mixed-layer CIN: -129 J/kg
Mixed-layer LCL: 581 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 114 m²/s²
0-3 km storm-relative helicity: 247 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.

812 
ACUS11 KWNS 100417
SWOMCD
SPC MCD 100417 
SDZ000-NEZ000-100515-

MESOSCALE DISCUSSION 0707
NWS STORM PREDICTION CENTER NORMAN OK
1117 PM CDT MON MAY 09 2011

AREAS AFFECTED...WRN SD...EXTREME NWRN NEB

CONCERNING...SEVERE THUNDERSTORM WATCH 267...

VALID 100417Z - 100515Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 267
CONTINUES.

SFC LOW HAS DRIFTED INTO NRN CHERRY COUNTY ALONG THE NEB/SD BORDER. 
THIS FEATURE WILL LIKELY BE DRAWN A BIT NWD OVER THE NEXT FEW HOURS
AS STRONGEST ZONE OF LOW LEVEL WARM ADVECTION REMAINS FOCUSED ACROSS
SD.  COINCIDENTALLY...MOST CONCENTRATED AREA OF TSTMS IS WITHIN THIS
ZONE OF FOCUSED ASCENT AND ACTIVITY IS LOOSELY ORGANIZING INTO AN
MCS.  THE BACK EDGE OF THE STRONGEST CONVECTION SHOULD SPREAD FROM
SW-NE ACROSS THE WW WITH NEW DEVELOPMENT PRIMARILY EXPECTED OVER THE
NRN HALF OF THE WATCH.

..DARROW.. 05/10/2011

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

ATTN...WFO...ABR...LBF...UNR...CYS...

LAT...LON   42510281 45820390 45830121 42530026 42510281

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 9, 8:16 PM MDT	Mesoscale Discussion	SPC	Box Butte, Dawes, Morrill, Scotts Bluff, Sioux	29 min
May 9, 8:34 PM MDT	Severe Thunderstorm Watch	SPC	Sheridan	5 hr
May 10, 12:56 AM MDT	Mesoscale Discussion	SPC	Butte, Corson, Dewey, Meade, Perkins, Stanley and 1 more	94 min

Nearby

Mesoscale Discussions in South Dakota, 2011 Mesoscale Discussions in Nebraska, 2011 Every mesoscale discussion in 2011

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.