Alert archive / South Dakota / Mesoscale Discussions in 2012

Mesoscale Discussion 666

May 2, 20125 counties in Minnesota; 12 counties in North Dakota; 17 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at May 2, 2012, 7:20 PM CDT for 5 counties in Minnesota; 12 counties in North Dakota; 17 counties in South Dakota. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: May 2, 2012, 7:20 PM CDT (00:20 UTC)
Expired: May 2, 2012, 8:15 PM CDT
In force: 55 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 34 counties

Big Stone County, MN, Clay County, MN, Grant County, MN, Traverse County, MN, Wilkin County, MN, Cass County, ND, Dickey County, ND, Emmons County, ND, Grant County, ND, LaMoure County, ND, Logan County, ND, McIntosh County, ND, Morton County, ND, Ransom County, ND, Richland County, ND, Sargent County, ND, Sioux County, ND, Brown County, SD, Campbell County, SD, Corson County, SD, Day County, SD, Dewey County, SD, Edmunds County, SD, Faulk County, SD, Grant County, SD, Marshall County, SD, McPherson County, SD, Potter County, SD, Roberts County, SD, Spink County, SD, Stanley County, SD, Sully County, SD, Walworth County, SD, Ziebach County, SD

The radar

The Aberdeen radar (KABR), 51 km from the middle of the area, began a volume at 00:22 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, 0.3 hours before the alert went out and 89 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: 10 J/kg
Mixed-layer CIN: -51 J/kg
Mixed-layer LCL: 2487 m above ground
0-6 km bulk shear: 67 kt
0-1 km storm-relative helicity: 119 m²/s²
0-3 km storm-relative helicity: 170 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.

876 
ACUS11 KWNS 030020
SWOMCD
SPC MCD 030020 
MNZ000-SDZ000-NDZ000-030115-

MESOSCALE DISCUSSION 0666
NWS STORM PREDICTION CENTER NORMAN OK
0720 PM CDT WED MAY 02 2012

AREAS AFFECTED...SRN ND...NRN SD INTO WEST CENTRAL MN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 030020Z - 030115Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...TSTMS WILL CONTINUE TO DEVELOP ACROSS SOUTH CENTRAL ND AND
FROM CENTRAL/NRN SD INTO NERN SD THIS EVENING...WITH SOME POTENTIAL
FOR ACTIVITY TO GROW UPSCALE INTO A FORWARD PROPAGATING CLUSTER OF
STORMS AFFECTING WEST CENTRAL MN LATER THIS EVENING.  HAIL NEAR OR
LOCALLY EXCEEDING 1 INCH WILL BE POSSIBLE ALONG WITH A THREAT FOR
STRONG WIND GUSTS.  THIS REGION WILL BE MONITORED FOR GREATER
COVERAGE OF STRONGER STORM POTENTIAL AT WHICH TIME A WW WOULD NEED
TO BE CONSIDERED.

DISCUSSION...EARLY EVENING SURFACE ANALYSIS INDICATED A COUPLE AREAS
OF LOW PRESSURE OVER WRN SD...WITH A WARM FRONT EXTENDING GENERALLY
EWD ALONG THE SD/ND BORDER INTO CENTRAL MN TO CENTRAL/NRN WI. WATER
VAPOR IMAGERY SHOWED A LEAD IMPULSE ADVANCING ENEWD THROUGH
WRN/CENTRAL ND AT THIS TIME...WITH FORCING FOR ASCENT ATTENDANT TO
THIS FEATURE LIKELY AIDING THE SMALL ONGOING CLUSTER OVER S CENTRAL
ND.  MEANWHILE...50 KT OF WSWLY MIDLEVEL FLOW ASSOCIATED WITH A MORE
PROMINENT MIDLEVEL TROUGH MOVING THROUGH THE NRN HIGH PLAINS WILL
MAINTAIN AN INCREASE IN EFFECTIVE BULK SHEAR ACROSS THE DAKOTAS AND
EVENTUALLY INTO CENTRAL MN.  ALTHOUGH EFFECTIVE BULK SHEAR OF 40-50
KT IS SUFFICIENT FOR ORGANIZED STORMS...THE LACK OF STRONGER
INSTABILITY ACROSS NRN SD INTO SRN ND AND WEST CENTRAL MN IS
CURRENTLY INHIBITING...AND MAY CONTINUE TO DO SO...THE OVERALL
COVERAGE OF STRONG TO SEVERE STORMS TO SUPPORT A WATCH ISSUANCE.

MODELS DO AGREE THAT A CLUSTER OF STORMS WILL MOVE EWD ACROSS NRN
SD/SRN ND INTO WEST CENTRAL MN THIS EVENING TO EARLY TONIGHT. 
HOWEVER...UNCERTAINTY REMAINS AS DISCUSSED IN THE NEED FOR A WW.

..PETERS/THOMPSON.. 05/03/2012

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

ATTN...WFO...MPX...FGF...ABR...BIS...UNR...

LAT...LON   44200119 44400193 45340208 45930212 46770147 46839988
            46999664 46819584 45919599 45429622 45139670 45029737
            44899811 44200119

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 2, 7:38 PM CDT	Mesoscale Discussion	SPC	Blue Earth, Brown, Cottonwood, Dodge, Faribault, Fillmore and 16 more	37 min
May 2, 7:47 PM CDT	Severe Thunderstorm Watch	SPC	Dodge, Fillmore, Houston, Mower, Olmsted, Wabasha and 1 more	5 hr
May 2, 9:18 PM CDT	Mesoscale Discussion	SPC	Blue Earth, Brown, Cottonwood, Faribault, Freeborn, Goodhue and 10 more	27 min
May 2, 11:06 PM CDT	Mesoscale Discussion	SPC	Anoka, Big Stone, Carver, Chippewa, Dakota, Hennepin and 17 more	24 min
May 3, 8:43 AM CDT	Mesoscale Discussion	SPC	Dakota, Dodge, Goodhue, Olmsted, Rice, Steele and 2 more	92 min
May 2, 10:43 PM CDT	Mesoscale Discussion	SPC	Clay, Union	62 min

Nearby

Mesoscale Discussions in South Dakota, 2012 Mesoscale Discussions in North Dakota, 2012 Mesoscale Discussions in Minnesota, 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.