Alert archive / Minnesota / Mesoscale Discussions in 2012

Mesoscale Discussion 653

May 1, 20126 counties in Minnesota; 5 counties in North Dakota

The Storm Prediction Center issued this mesoscale discussion at May 1, 2012, 6:57 PM CDT for 6 counties in Minnesota; 5 counties in North Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 1, 2012, 6:57 PM CDT (23:57 UTC)
Expired: May 1, 2012, 9:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Kittson County, MN, Lake of the Woods County, MN, Marshall County, MN, Pennington County, MN, Polk County, MN, Roseau County, MN, Grand Forks County, ND, Griggs County, ND, Nelson County, ND, Steele County, ND, Traill County, ND

The radar

The Fargo/Grand Forks radar (KMVX), 121 km from the middle of the area, began a volume at 23:55 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

International Fa, MN (KINL), launched 12:00Z, 12.0 hours before the alert went out and 226 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: 1266 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 82 m²/s²
0-3 km storm-relative helicity: 147 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.

488 
ACUS11 KWNS 012357
SWOMCD
SPC MCD 012357 
MNZ000-NDZ000-020200-

MESOSCALE DISCUSSION 0653
NWS STORM PREDICTION CENTER NORMAN OK
0657 PM CDT TUE MAY 01 2012

AREAS AFFECTED...PORTIONS NWRN MN...NERN AND E-CENTRAL ND.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 012357Z - 020200Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...POTENTIAL WILL CONTINUE THROUGH AROUND 03Z FOR OCNL SVR
HAIL WITH BKN/SW-NE BAND OF MULTICELLULAR TSTMS MOVING EWD OVER
DISCUSSION AREA.

DISCUSSION...23Z SFC MESOANALYSIS SHOWED LOW OVER EXTREME NERN
ND...WITH WAVY/OCCLUDED FRONT SSEWD OVER FAR AREA THEN SEWD TO
TRIPLE-POINT LOW IN W-CENTRAL MN.  THIS LOW SHOULD MOVE EWD ACROSS
NW ANGLE AREA OF MN WITH OCCLUDED FRONT DOING LIKEWISE OVER
NWRN/N-CENTRAL MN.  CORRIDOR OF SFC SELYS AND RELATED LOW-LEVEL
MOISTURE HAS BECOME JUXTAPOSED WITH LATE-AFTERNOON SFC HEATING INVOF
FRONT...LEADING TO WEAKLY CAPPED PLUME OF 500-1000 MLCAPE ASTRIDE
RED RIVER VALLEY.  DEEP-LAYER SHEAR WEAKENS WITH NWWD EXTENT...I.E.
EFFECTIVE SHEAR MAGNITUDES NEAR 50 KT OVER NERN PORTIONS WW 220 BUT
AROUND 30 KT OVER NERN SD AND EXTREME NWRN MN.  UPPER FLOW LIKELY
WILL BACK WITH TIME AHEAD OF MID-UPPER LEVEL PERTURBATION MOVING
ENEWD OUT OF WY AND WRN SD...REDUCING DEEP-LAYER SHEAR SOMEWHAT. 
ALSO...COMBINATION OF DIABATIC SFC COOLING...AND SPREAD OF OUTFLOW
FROM EXISTING CONVECTION...WILL CONTRIBUTE TO
STABILIZATION...ESPECIALLY AFTER ABOUT 01Z.

..EDWARDS/CORFIDI.. 05/01/2012

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

ATTN...WFO...FGF...BIS...

LAT...LON   47609858 48509754 48979724 48989512 49359507 49319482
            49169481 48959468 48779470 48439499 47669656 47069775
            47279860 47609858

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 1, 2:30 PM CDT	Mesoscale Discussion	SPC	Big Stone, Blue Earth, Brown, Chippewa, Cottonwood, Douglas and 24 more	60 min
May 1, 2:59 PM CDT	Tornado Watch	SPC	Benton, Big Stone, Brown, Chippewa, Cottonwood, Douglas and 31 more	6 hr
May 1, 6:10 PM CDT	Tornado Watch	SPC	Anoka, Blue Earth, Brown, Carver, Chisago, Dakota and 16 more	6 hr
May 1, 6:11 PM CDT	Mesoscale Discussion	SPC	Anoka, Benton, Blue Earth, Brown, Carver, Chippewa and 36 more	94 min

Nearby

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