Alert archive / Minnesota / Mesoscale Discussions in 2012

Mesoscale Discussion 940

May 28, 201223 counties in Minnesota; 14 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at May 28, 2012, 1:48 PM CDT for 23 counties in Minnesota; 14 counties in Wisconsin. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued: May 28, 2012, 1:48 PM CDT (18:48 UTC)
Expired: May 28, 2012, 2:45 PM CDT
In force: 57 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 37 counties

Anoka County, MN, Benton County, MN, Carlton County, MN, Carver County, MN, Chisago County, MN, Dakota County, MN, Hennepin County, MN, Isanti County, MN, Kanabec County, MN, Kandiyohi County, MN, McLeod County, MN, Meeker County, MN, Mille Lacs County, MN, Morrison County, MN, Pine County, MN, Ramsey County, MN, Renville County, MN, Scott County, MN, Sherburne County, MN, Sibley County, MN, Stearns County, MN, Washington County, MN, Wright County, MN, Ashland County, WI, Barron County, WI, Bayfield County, WI, Burnett County, WI, Chippewa County, WI, Douglas County, WI, Dunn County, WI, Pepin County, WI, Pierce County, WI, Polk County, WI, Rusk County, WI, Saint Croix County, WI, Sawyer County, WI, Washburn County, WI

The radar

The Minneapolis radar (KMPX), 114 km from the middle of the area, began a volume at 18:48 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 309May 28, 2:10 PM CDT

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 6.8 hours before the alert went out and 115 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: 60 J/kg
Mixed-layer CIN: -27 J/kg
Mixed-layer LCL: 553 m above ground
0-6 km bulk shear: 69 kt
0-1 km storm-relative helicity: 92 m²/s²
0-3 km storm-relative helicity: 144 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

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

662 
ACUS11 KWNS 281848
SWOMCD
SPC MCD 281848 
WIZ000-MNZ000-281945-

MESOSCALE DISCUSSION 0940
NWS STORM PREDICTION CENTER NORMAN OK
0148 PM CDT MON MAY 28 2012

AREAS AFFECTED...MN...WI

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 281848Z - 281945Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...ANOTHER ROUND OF SEVERE WEATHER APPEARS INCREASINGLY
LIKELY ACROSS PORTIONS OF ERN/NRN MN INTO WRN WI THIS AFTERNOON AS A
STRONG UPPER LEVEL STORM SYSTEM SPINS OVER THE NRN PLAINS. A WATCH
IS LIKELY OVER SOME OF ERN MN AND WRN WI SHORTLY.

DISCUSSION...NEW TSTM DEVELOPMENT APPEARS LIKELY ALONG A FRONTAL
SURGE MOVING INTO CNTRL AND ERN MN THIS AFTERNOON. THIS DEVELOPMENT
WILL BE IN ADDITION TO THE ISOLATED ONGOING STORMS WEST OF DLH ATTM.
STRONG SURFACE HEATING HAS CONTRIBUTED TO MLCAPE AROUND 1000 J/KG
AHEAD OF THE FRONT/WIND SHIFT. EFFECTIVE SHEAR ACROSS THIS AREA IS
STRONG BENEATH A BAND OF 40-50KT MID LEVEL FLOW ALOFT. ASCENT ACROSS
THE BOUNDARY SHOULD BE AIDED BY STRONG DCVA ON THE POLEWARD SIDE OF
THE STRONGER JET MAX CROSSING WI ATTM. GIVEN THESE
CONDITIONS...EXPECT AN INCREASE IN STORMS AND STORM ORGANIZATION.
UPDRAFT PERSISTENCE AND FORCING ALONG THE ADVANCING WIND SHIFT WILL
LIKELY RESULT IN LINE SEGMENTS AND PERHAPS SUPERCELLS WITH A THREAT
FOR LARGE HAIL AND STRONG WINDS. AN ISOLATED TORNADO CANNOT BE
COMPLETELY RULED OUT...ESPECIALLY IF STORMS CAN INITIATION NEAR THE
WEAK SURFACE CIRCULATION WEST OF THE TWIN CITIES. HOWEVER...LIMITED
LOW LEVEL SHEAR ACROSS MOST OF THE AREA SHOULD PRECLUDE THE NEED FOR
A TORNADO WATCH AT THIS TIME.

..CARBIN.. 05/28/2012

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

ATTN...WFO...DLH...ARX...MPX...

LAT...LON   46579057 45299094 44799126 44599159 44489237 44489460
            44649504 45079506 45519478 45829463 46069425 46409318
            46939258 47199195 47129141 46579057

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 27, 7:47 PM CDT	Mesoscale Discussion	SPC	Aitkin, Anoka, Benton, Carlton, Carver, Chippewa and 33 more	88 min
May 27, 9:51 PM CDT	Mesoscale Discussion	SPC	Blue Earth, Jackson, Martin, Nicollet, Watonwan	84 min
May 27, 10:11 PM CDT	Mesoscale Discussion	SPC	Aitkin, Anoka, Benton, Blue Earth, Brown, Carlton and 45 more	94 min
May 28, 2:07 PM CDT	Severe Thunderstorm Watch	SPC	Anoka, Benton, Carlton, Carver, Chisago, Dakota and 14 more	6 hr
May 28, 3:58 PM CDT	Mesoscale Discussion	SPC	Anoka, Benton, Carlton, Carver, Chisago, Dakota and 16 more	92 min
May 28, 12:00 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Calumet, Clark, Columbia, Crawford and 34 more	60 min
May 28, 12:54 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Brown, Calumet, Clark, Columbia, Crawford and 47 more	7 hr
May 28, 6:28 PM CDT	Mesoscale Discussion	SPC	Barron, Chippewa, Dunn, Rusk, Sawyer, Washburn	62 min

Nearby

Mesoscale Discussions in Minnesota, 2012 Mesoscale Discussions in Wisconsin, 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.