Alert archive / Minnesota / Mesoscale Discussions in 2012

Mesoscale Discussion 926

May 27, 201225 counties in Minnesota; 7 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at May 27, 2012, 3:49 PM CDT for 25 counties in Minnesota; 7 counties in Wisconsin. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: May 27, 2012, 3:49 PM CDT (20:49 UTC)
Expired: May 27, 2012, 4:45 PM CDT
In force: 56 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 32 counties

Anoka County, MN, Benton County, MN, Chisago County, MN, Crow Wing County, MN, Douglas County, MN, Grant County, MN, Hennepin County, MN, Isanti County, MN, Kanabec County, MN, Kandiyohi County, MN, Meeker County, MN, Mille Lacs County, MN, Morrison County, MN, Otter Tail County, MN, Pine County, MN, Pope County, MN, Ramsey County, MN, Sherburne County, MN, Stearns County, MN, Stevens County, MN, Todd County, MN, Traverse County, MN, Washington County, MN, Wilkin County, MN, Wright County, MN, Barron County, WI, Burnett County, WI, Polk County, WI, Rusk County, WI, Saint Croix County, WI, Sawyer County, WI, Washburn County, WI

The radar

The Minneapolis radar (KMPX), 96 km from the middle of the area, began a volume at 20:52 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 307May 27, 6:10 PM CDT

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 8.8 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: 845 J/kg
Mixed-layer CIN: -438 J/kg
Mixed-layer LCL: 662 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 380 m²/s²
0-3 km storm-relative helicity: 375 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.

641 
ACUS11 KWNS 272049
SWOMCD
SPC MCD 272049 
WIZ000-MNZ000-SDZ000-NDZ000-272145-

MESOSCALE DISCUSSION 0926
NWS STORM PREDICTION CENTER NORMAN OK
0349 PM CDT SUN MAY 27 2012

AREAS AFFECTED...CNTRL MN INTO NWRN WI

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 272049Z - 272145Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...WARM SECTOR ACROSS CNTRL MN INTO NWRN WI IS BEING
MONITORED FOR A TORNADO WW. CONVECTIVE INITIATION IS POSSIBLE OVER
THE NEXT HOUR OR TWO.

DISCUSSION...ALTHOUGH THE AREA HAS REMAINED CAPPED BENEATH A STRONG
EML...INCREASING FORCING FOR ASCENT WITH AN APPROACHING LARGER SCALE
UPPER TROUGH...AND AMPLE SURFACE HEATING /TEMPERATURES IN THE MID
80S F/ ARE CONTRIBUTING TO AN EROSION OF THE REMAINING CONVECTIVE
INHIBITION. THE WARM FRONT /PER 20Z SURFACE OBSERVATIONS/ HAS
PROGRESSED NWD TO CNTRL MN AND NWRN WI...WHILE A NE-SW ORIENTED COLD
FRONT HAS REACHED WRN MN. THE POTENTIAL EXISTS FOR DISCRETE AND
ROBUST UPDRAFTS WITHIN THE WARM SECTOR. INITIAL DEVELOPMENT WILL
LIKELY BE SUPERCELLULAR...ESPECIALLY INVOF OF THE WARM FRONT WHERE
DEEP-LAYER SHEAR VECTORS ARE LARGELY ORTHOGONAL TO THE FRONTAL
BOUNDARY. WITH INCREASINGLY FOCUSED SURFACE CONVERGENCE ALONG THE
COLD FRONT...A FORCED LINE OF CONVECTION AND SUBSEQUENT WIND THREAT
WILL BECOME LIKELY THIS EVENING.

..HURLBUT/CARBIN.. 05/27/2012

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

ATTN...WFO...DLH...MPX...FGF...ABR...

LAT...LON   44969470 45489628 46079677 46529661 46419573 46529404
            46369150 45669098 45189129 44839258 44799313 44969470

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 26, 7:56 PM CDT	Mesoscale Discussion	SPC	Aitkin, Carlton, Crow Wing, Itasca, Pine	2 hr
May 26, 11:57 PM CDT	Mesoscale Discussion	SPC	Becker, Benton, Clay, Crow Wing, Douglas, Grant and 12 more	93 min
May 27, 2:58 PM CDT	Mesoscale Discussion	SPC	Cottonwood, Jackson, Martin, Murray, Nobles, Rock	62 min
May 27, 3:42 PM CDT	Severe Thunderstorm Watch	SPC	Brown, Cottonwood, Jackson, Lincoln, Lyon, Martin and 6 more	8 hr
May 27, 6:08 PM CDT	Severe Thunderstorm Watch	SPC	Aitkin, Anoka, Benton, Blue Earth, Brown, Carver and 40 more	7 hr
May 27, 6:55 PM CDT	Mesoscale Discussion	SPC	Blue Earth, Cottonwood, Jackson, Martin, Murray, Nobles and 3 more	2 hr

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.