Alert archive / Minnesota / Mesoscale Discussions in 2011

Mesoscale Discussion 839

May 21, 201148 counties in Minnesota; Polk County, Saint Croix County, Wisconsin

The Storm Prediction Center issued this mesoscale discussion at May 21, 2011, 4:55 PM CDT for 48 counties in Minnesota; Polk County, Saint Croix County, Wisconsin. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued: May 21, 2011, 4:55 PM CDT (21:55 UTC)
Expired: May 21, 2011, 6:30 PM CDT
In force: 95 min
Issued by: the Storm Prediction Center

All 50 counties

Anoka County, MN, Benton County, MN, Big Stone County, MN, Blue Earth County, MN, Brown County, MN, Carver County, MN, Chippewa County, MN, Chisago County, MN, Cottonwood County, MN, Crow Wing County, MN, Dakota County, MN, Dodge County, MN, Douglas County, MN, Goodhue County, MN, Grant County, MN, Hennepin County, MN, Isanti County, MN, Kanabec County, MN, Kandiyohi County, MN, Lac qui Parle County, MN, Le Sueur County, MN, Lyon County, MN, McLeod County, MN, Meeker County, MN, Mille Lacs County, MN, Morrison County, MN, Murray County, MN, Nicollet County, MN, Otter Tail County, MN, Pine County, MN, Pope County, MN, Ramsey County, MN, Redwood County, MN, Renville County, MN, Rice County, MN, Scott County, MN, Sherburne County, MN, Sibley County, MN, Stearns County, MN, Steele County, MN, Stevens County, MN, Swift County, MN, Todd County, MN, Waseca County, MN, Washington County, MN, Watonwan County, MN, Wright County, MN, Yellow Medicine County, MN, Polk County, WI, Saint Croix County, WI

The radar

The Minneapolis radar (KMPX), 97 km from the middle of the area, began a volume at 21:55 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

Minneapolis, MN (KMPX), launched 12:00Z, 9.9 hours before the alert went out and 94 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: 2 J/kg
Mixed-layer CIN: -114 J/kg
Mixed-layer LCL: 474 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 206 m²/s²
0-3 km storm-relative helicity: 240 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.

417 
ACUS11 KWNS 212155
SWOMCD
SPC MCD 212155 
WIZ000-MNZ000-SDZ000-212330-

MESOSCALE DISCUSSION 0839
NWS STORM PREDICTION CENTER NORMAN OK
0455 PM CDT SAT MAY 21 2011

AREAS AFFECTED...SRN/CNTRL PORTIONS OF MN...FAR WRN WI

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 212155Z - 212330Z

MARGINAL SVR WEATHER THREAT WILL LIKELY EXIST THROUGH THE REMAINDER
OF THE AFTERNOON OVER PORTIONS OF SRN/CNTRL MN AND FAR WRN
WI...PRIMARY THREATS BEING LARGE HAIL AND DAMAGING WIND GUSTS.
HOWEVER...SVR COVERAGE IS EXPECTED TO BE TOO LIMITED ATTM TO SUPPORT
WW ISSUANCE.

SURFACE OBSERVATIONS AT 21Z INDICATE A WARM FRONT IS LIFTING NWD
ACROSS SRN PORTIONS OF MN. AIRMASS DESTABILIZATION AND ASCENT ALONG
THE FRONT...AS WELL AS UPPER IMPULSE MOVING N ACROSS THE AREA...HAVE
AIDED IN THUNDERSTORM INITIATION...WITH THE STRONGEST STORMS
OCCURRING IMMEDIATELY W OF MSP AT 2145Z. WITH MLCAPE VALUES
INCREASING TO AROUND 1000 J/KG...COMBINED WITH SLY 50 KT MIDLEVEL
SPEED MAX...SVR STORMS/BRIEF SUPERCELLS WILL BE POSSIBLE THROUGH THE
REMAINDER OF THE AFTERNOON...BEFORE BOUNDARY LAYER COOLS/STABILIZES.
THOUGH ISOLATED LARGE HAIL/DAMAGING WIND GUSTS WILL BE THE PRIMARY
THREATS...ENLARGED LOW-LEVEL HODOGRAPH STRUCTURE /PER MPX VWP/
CHARACTERIZED BY 0-1 KM SRH NEAR 150 M2 S-2 SUGGESTS A
BRIEF/ISOLATED TORNADO MAY ALSO BE POSSIBLE.

..GARNER.. 05/21/2011

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

ATTN...WFO...DLH...ARX...MPX...FGF...FSD...ABR...

LAT...LON   45989631 46579556 46619369 46089245 45059232 43909279
            43739441 43899595 45009658 45989631

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 21, 12:51 PM CDT	Mesoscale Discussion	SPC	Jackson, Nobles, Rock	114 min

Nearby

Mesoscale Discussions in Minnesota, 2011 Mesoscale Discussions in Wisconsin, 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.