Alert archive / South Dakota / Mesoscale Discussions in 2012

Mesoscale Discussion 905

May 26, 20125 counties in Nebraska; 21 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at May 26, 2012, 1:58 AM CDT for 5 counties in Nebraska; 21 counties in South Dakota. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued: May 26, 2012, 1:58 AM CDT (06:58 UTC)
Expired: May 26, 2012, 3:30 AM CDT
In force: 92 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 26 counties

Boyd County, NE, Holt County, NE, Keya Paha County, NE, Knox County, NE, Rock County, NE, Aurora County, SD, Bennett County, SD, Bon Homme County, SD, Brule County, SD, Buffalo County, SD, Charles Mix County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Hanson County, SD, Hutchinson County, SD, Jackson County, SD, Jerauld County, SD, Jones County, SD, Lyman County, SD, Mellette County, SD, Stanley County, SD, Todd County, SD, Tripp County, SD, Turner County, SD, Yankton County, SD

The radar

The North Platte radar (KLNX), 166 km from the middle of the area, began a volume at 06:58 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

Aberdeen, SD (KABR), launched 00:00Z, 7.0 hours before the alert went out and 206 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1774 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 23 m²/s²
0-3 km storm-relative helicity: 54 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.

447 
ACUS11 KWNS 260659
SWOMCD
SPC MCD 260658
SDZ000-NEZ000-260830-

MESOSCALE DISCUSSION 0905
NWS STORM PREDICTION CENTER NORMAN OK
0158 AM CDT SAT MAY 26 2012

AREAS AFFECTED...PARTS OF NRN NEBRASKA INTO SRN/CNTRL SOUTH DAKOTA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 260658Z - 260830Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...INCREASING STORMS LIKELY ACROSS THE REGION THROUGH
DAYBREAK.  A WW IS NOT NECESSARILY ANTICIPATED...BUT TRENDS WILL BE
MONITORED.

DISCUSSION...LATEST INFRARED SATELLITE IMAGERY IS SUGGESTIVE THAT
UPWARD VERTICAL MOTION IS INCREASING WITHIN A ZONE OF STRENGTHENING
LOWER/MID TROPOSPHERIC WARM ADVECTION ACROSS NORTHERN NEBRASKA INTO
SOUTHERN SOUTH DAKOTA.  THIS IS NEAR THE CREST OF THE AMPLIFYING
LARGE-SCALE UPPER RIDGE...AROUND WHICH THE PROGRESSION OF A HIGH
LEVEL JET MAY CONTRIBUTE TO INCREASINGLY DIVERGENT UPPER FLOW ACROSS
THE NORTH CENTRAL PLAINS BETWEEN NOW AND DAYBREAK.  INCREASING
CONVECTIVE DEVELOPMENT APPEARS LIKELY THROUGH THE 09-11Z TIME
FRAME...PERHAPS BECOMING MOST CONCENTRATED NORTH OF THE
NEBRASKA/SOUTH DAKOTA BORDER INTO PARTS OF CENTRAL SOUTH
DAKOTA...JUST TO THE NORTH OF WARMER AND MORE STRONGLY CAPPING
ELEVATED MIXED LAYER AIR.  SIZABLE CAPE AND CONVECTIVE LAYER SHEAR
PROBABLY WILL CONTRIBUTE TO THE RISK FOR AT LEAST OCCASIONAL SEVERE
HAIL IN STRONGEST STORMS.  DAMAGING WIND POTENTIAL...WELL TO THE
NORTH OF THE SURFACE FRONTAL ZONE...APPEARS LOW.  BUT AT LEAST SOME
POTENTIAL APPEARS TO EXIST FOR STORM CONSOLIDATION AND THE UPSCALE
GROWTH OF AN ORGANIZED STORM CLUSTER.  IF THIS OCCURS...THE
DEVELOPMENT OF A SIGNIFICANT PRESSURE PERTURBATION ACCOMPANIED BY
STRONG SURFACE WIND GUSTS MAY NOT BE OUT OF THE QUESTION.

..KERR/MEAD.. 05/26/2012

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

ATTN...WFO...FSD...OAX...ABR...LBF...UNR...

LAT...LON   43800245 44450078 43949766 43259690 42459744 42319896
            42670161 43800245

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 25, 9:17 PM CDT	Mesoscale Discussion	SPC	Adams, Boone, Buffalo, Burt, Butler, Cass and 43 more	88 min
May 26, 12:46 AM CDT	Mesoscale Discussion	SPC	Burt, Dakota, Thurston	89 min
May 26, 3:48 PM CDT	Mesoscale Discussion	SPC	Adams, Antelope, Boone, Buffalo, Burt, Butler and 50 more	87 min
May 26, 3:55 PM CDT	Mesoscale Discussion	SPC	Arthur, Banner, Box Butte, Cheyenne, Deuel, Garden and 7 more	2 hr
May 26, 4:48 PM CDT	Severe Thunderstorm Watch	SPC	Arthur, Blaine, Boyd, Brown, Cherry, Custer and 15 more	5 hr
May 26, 6:44 PM CDT	Mesoscale Discussion	SPC	Arthur, Blaine, Brown, Cherry, Garden, Garfield and 9 more	91 min
May 26, 5:43 AM CDT	Mesoscale Discussion	SPC	Beadle, Brookings, Brown, Clark, Codington, Day and 17 more	92 min

Nearby

Mesoscale Discussions in South Dakota, 2012 Mesoscale Discussions in Nebraska, 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.