Alert archive / Wisconsin / Mesoscale Discussions in 2011

Mesoscale Discussion 758

May 12, 201134 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at May 12, 2011, 1:08 PM CDT for 34 counties in Wisconsin. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued: May 12, 2011, 1:08 PM CDT (18:08 UTC)
Expired: May 12, 2011, 2:15 PM CDT
In force: 67 min
Issued by: the Storm Prediction Center

All 34 counties

Adams County, WI, Calumet County, WI, Chippewa County, WI, Clark County, WI, Columbia County, WI, Dane County, WI, Dodge County, WI, Eau Claire County, WI, Fond du Lac County, WI, Green Lake County, WI, Iowa County, WI, Jackson County, WI, Jefferson County, WI, Juneau County, WI, La Crosse County, WI, Langlade County, WI, Lincoln County, WI, Marathon County, WI, Marquette County, WI, Menominee County, WI, Monroe County, WI, Outagamie County, WI, Portage County, WI, Richland County, WI, Sauk County, WI, Shawano County, WI, Taylor County, WI, Trempealeau County, WI, Vernon County, WI, Washington County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI, Wood County, WI

The radar

The La Crosse radar (KARX), 111 km from the middle of the area, began a volume at 18:08 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 291May 12, 1:40 PM CDT

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 12:00Z, 6.1 hours before the alert went out and 147 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: 122 J/kg
Mixed-layer CIN: -257 J/kg
Mixed-layer LCL: 929 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 79 m²/s²
0-3 km storm-relative helicity: 130 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.

747 
ACUS11 KWNS 121809
SWOMCD
SPC MCD 121808
WIZ000-121915-

MESOSCALE DISCUSSION 0758
NWS STORM PREDICTION CENTER NORMAN OK
0108 PM CDT THU MAY 12 2011

AREAS AFFECTED...WI

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 121808Z - 121915Z

AREAS OF CENTRAL AND SRN WI ARE BEING MONITORED FOR THUNDERSTORM
DEVELOPMENT THIS AFTERNOON. STRONG INSTABILITY AND SOME POTENTIAL
FOR STORM PERSISTENCE/ORGANIZATION SUGGEST THAT A WATCH WILL LIKELY
BE NEEDED SHORTLY.

STRONG SURFACE HEATING AND MOIST AIR MASS ARE CONTRIBUTING TO THE
DEVELOPMENT OF MODEST MLCAPE NEARING 1500 J PER KG ACROSS SRN WI AND
500-1000 J PER KG FARTHER NORTH INTO CENTRAL WI EARLY THIS
AFTERNOON. A QUICK LOOK AT FCST SOUNDINGS INDICATED LITTLE
CONVECTIVE INHIBITION REMAINS AND EXPECT STORM DEVELOPMENT TO OCCUR
OVER THE NEXT HOUR OR SO. STORM PERSISTENCE/ORGANIZATION MAY BE
LIMITED BY LACK OF GREATER FLOW/SHEAR ACROSS THE REGION.
HOWEVER...WEAK MCV AND ASSOCIATED FRONTAL LOW/WAVE MOVING ALONG WELL
DEFINED QUASI-STATIONARY FRONTAL BOUNDARY FROM NERN IA TO NCNTRL
WI...IN ADDITION TO LAKE-BREEZE REINFORCED BOUNDARY ACROSS ERN
WI...MAY LEND SOME LOCALLY ENHANCED SUPPORT FOR BOTH STORM
INITIATION AND PERSISTENCE. A SCATTERING OF SEVERE HAIL/WIND EVENTS
APPEARS POSSIBLE FROM PRIMARILY MULTICELL STORMS DEVELOPING IN AN
INCREASINGLY WARM AND UNSTABLE AIR MASS.

..CARBIN.. 05/12/2011

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

ATTN...WFO...GRB...MKX...DLH...ARX...MPX...

LAT...LON   43298807 44458817 44978817 45388880 45549000 45379096
            45129150 44499175 44199154 43709111 43039080 42889063
            42698980 42848850 43298807

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 12, 1:41 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Brown, Calumet, Chippewa, Clark, Columbia and 50 more	5 hr
May 12, 6:16 PM CDT	Mesoscale Discussion	SPC	Brown, Calumet, Clark, Forest, Langlade, Lincoln and 12 more	29 min

Nearby

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.