Alert archive / Wisconsin / Mesoscale Discussions in 2012

Mesoscale Discussion 1587

July 25, 20124 counties in Michigan; 23 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Jul 25, 2012, 3:57 PM EDT for 4 counties in Michigan; 23 counties in Wisconsin. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 25, 2012, 3:57 PM EDT (19:57 UTC)
Expired: Jul 25, 2012, 6:00 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 27 counties

Manistee County, MI, Mason County, MI, Muskegon County, MI, Oceana County, MI, Brown County, WI, Calumet County, WI, Clark County, WI, Eau Claire County, WI, Fond du Lac County, WI, Jackson County, WI, Kewaunee County, WI, Langlade County, WI, Lincoln County, WI, Manitowoc County, WI, Marathon County, WI, Menominee County, WI, Oconto County, WI, Outagamie County, WI, Ozaukee County, WI, Portage County, WI, Shawano County, WI, Sheboygan County, WI, Taylor County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI, Wood County, WI

The radar

The Green Bay radar (KGRB), 27 km from the middle of the area, began a volume at 20:01 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 520Jul 25, 7:40 PM EDT

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 12:00Z, 8.0 hours before the alert went out and 25 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: 1621 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 124 m²/s²
0-3 km storm-relative helicity: 230 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.

324 
ACUS11 KWNS 251957
SWOMCD
SPC MCD 251957 
MIZ000-WIZ000-252200-

MESOSCALE DISCUSSION 1587
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT WED JUL 25 2012

AREAS AFFECTED...MUCH OF CENTRAL AND NRN WI...FAR WRN MI

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 251957Z - 252200Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...RAPID CONVECTIVE DEVELOPMENT MAY OCCUR IN THE NEXT FEW
HOURS...WITH A DAMAGING WIND THREAT DEVELOPING. THIS THREAT COULD
BECOME ORGANIZED AND MOVE EWD INTO LOWER MI LATER THIS EVENING.

DISCUSSION...SURFACE ANALYSIS SHOWS LOW PRESSURE CENTERED NEAR
LSE...WITH TROUGH EXTENDING NWWD NEAR THE MS RIVER. A COLD FRONT WAS
MOVING SEWD ACROSS THE MSP AREA...EXTENDING SWWD TOWARD FSD.
MEANWHILE...A WARM FRONT CONTINUED TO LIFT NWD ACROSS WI...EXTENDING
FROM NEAR MSP TO GRB AT 20Z.

STRONG HEATING HAS BEEN OCCURRING ALL DAY ACROSS THE WARM
SECTOR...WITH TEMPERATURES OVER 100F INTO SWRN WI. AIRCRAFT
SOUNDINGS NEAR MSP INDICATE CAPPING BUT STRONG TCU DEVELOPMENT NE OF
LSE SUGGEST CIN IS ERODING THERE. THE CORRIDOR FROM CNTRL WI SWWD
ALIGNS WITH THE LOW LEVEL JET AS WELL...WHICH WILL CONTINUE TO PUSH
WARM AIR NEWD OVER THE WARM FRONT WITH PRESSURE FALLS NOTED OVER WI.
TO THE W...THE COLD FRONT WILL ALSO CONTINUE SEWD...WITH PRESSURE
RISES. FORCING OVER THE REGION SHOULD INCREASE AS THE FRONT
PROGRESSES SEWD. THE ATMOSPHERE HAS BECOME VERY UNSTABLE AND STORMS
ARE EXPECTED TO FORM ACROSS CNTRL WI. WLY DEEP LAYER SHEAR OF 40-45
KT ALONG WITH MODEST LOW LEVEL VEERING WINDS MAY SUPPORT SUPERCELLS
INITIALLY...BUT LIKELY TRANSITIONING QUICKLY INTO AN MCS WITH
DAMAGING WINDS LIKELY. ONCE FORMED...THIS SYSTEM WOULD LIKELY
PERSIST FOR SOME TIME INTO LOWER MI LATER THIS EVENING.

..JEWELL/HART.. 07/25/2012

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

ATTN...WFO...APX...GRR...MQT...GRB...MKX...DLH...ARX...MPX...

LAT...LON   43368751 43888903 44209089 44409129 44729136 45109121
            45639015 45548923 45288784 44928695 44608615 44288598
            43798612 43528624 43408639 43348654 43318664 43368751

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 25, 6:24 AM EDT	Mesoscale Discussion	SPC	Gogebic	66 min
Jul 25, 7:25 PM EDT	Mesoscale Discussion	SPC	Arenac, Bay, Benzie, Clare, Clinton, Genesee and 22 more	95 min
Jul 25, 7:38 PM EDT	Severe Thunderstorm Watch	SPC	Alcona, Arenac, Benzie, Clare, Clinton, Crawford and 23 more	7 hr
Jul 25, 3:05 AM EDT	Mesoscale Discussion	SPC	Ashland, Bayfield, Burnett, Douglas, Iron, Price and 3 more	55 min
Jul 25, 3:24 AM EDT	Severe Thunderstorm Watch	SPC	Ashland, Barron, Bayfield, Burnett, Douglas, Iron and 5 more	5 hr
Jul 25, 6:16 PM EDT	Severe Thunderstorm Watch	SPC	Adams, Buffalo, Crawford, Grant, Jackson, Juneau and 5 more	8 hr

Nearby

Mesoscale Discussions in Wisconsin, 2012 Mesoscale Discussions in Michigan, 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.