Alert archive / Iowa / Mesoscale Discussions in 2012

Mesoscale Discussion 1591

July 25, 201231 counties in Iowa; 5 counties in Minnesota; La Crosse County, Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Jul 25, 2012, 7:20 PM CDT for 31 counties in Iowa; 5 counties in Minnesota; La Crosse County, Wisconsin. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued
Jul 25, 2012, 7:20 PM CDT (00:20 UTC)
Expired
Jul 25, 2012, 8:45 PM CDT
In force
85 min
Issued by
the Storm Prediction Center
All 37 counties

Black Hawk County, IA, Boone County, IA, Bremer County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Dallas County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Marshall County, IA, Mitchell County, IA, Pocahontas County, IA, Polk County, IA, Sac County, IA, Story County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Fillmore County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Winona County, MN, La Crosse County, WI

The radar

The Des Moines radar (KDMX), 130 km from the middle of the area, began a volume at 00:23 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

Minneapolis, MN (KMPX), launched 00:00Z, 0.3 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-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 2012-07-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 837 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 00:00Z on 2012-07-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -72 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
837 J/kg
Mixed-layer CIN
-60 J/kg
Mixed-layer LCL
1266 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
-72 m²/s²
0-3 km storm-relative helicity
59 m²/s²
Significant tornado parameter
-0.2
Supercell composite
-3.3

Open this sounding in Storm Lab

The text

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

844 
ACUS11 KWNS 260020
SWOMCD
SPC MCD 260020 
WIZ000-IAZ000-MNZ000-260145-

MESOSCALE DISCUSSION 1591
NWS STORM PREDICTION CENTER NORMAN OK
0720 PM CDT WED JUL 25 2012

AREAS AFFECTED...WEST-CENTRAL/NORTHERN IA AND SOUTHERN MN/WESTERN WI

CONCERNING...SEVERE THUNDERSTORM WATCH 519...

VALID 260020Z - 260145Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 519
CONTINUES.

SUMMARY...SEVERE TSTM WATCH 519 CONTINUES UNTIL 06Z. POTENTIAL
CONTINUES FOR DAMAGING WINDS/SEVERE HAIL...ESPECIALLY ACROSS
PORTIONS OF WEST-CENTRAL/NORTHERN IA IN THE SHORT-TERM...IN ADDITION
TO FAR SOUTHERN MN/WESTERN WI. ADDITION PORTIONS OF CENTRAL IA MAY
NEED TO BE INCLUDED INTO WW 519 PENDING SHORT-TERM CONVECTION
TRENDS.

DISCUSSION...PRIMARY SHORT-TERM SEVERE THREAT EXISTS ACROSS
WEST-CENTRAL/NORTH-CENTRAL IA EARLY THIS EVENING...AS SEVERAL
ORGANIZING/FORWARD PROPAGATING CLUSTERS HAVE EVOLVED. A 51 WIND GUST
WAS RECENTLY /AROUND 2355Z/ MEASURED IN DENISON IA. THESE CLUSTERS
APPEAR TO BE FAVORING THE IMMEDIATE WAKE OF A PRE-FRONTAL OUTFLOW
BOUNDARY...AND SOME ADDITIONAL FORWARD PROPAGATION/
EAST-SOUTHEASTWARD ACCELERATION SEEMS PROBABLE INTO WHAT REMAINS A
HOT /UPPER 90S TO LOWER 100S F/ AND MODERATELY UNSTABLE /2500 J PER
KG MLCAPE/ ENVIRONMENT ACROSS A LARGE PART OF CENTRAL/NORTHERN IA.
AS SUCH...DAMAGING WINDS/BOUTS OF SEVERE HAIL WILL REMAIN A CONCERN
THROUGH AT LEAST THE 01Z-03Z TIME FRAME ACROSS PORTIONS OF IA. OTHER
STRONG/SEVERE TSTMS MAY EXPAND ALONG THE FRONTAL ZONE INTO SOUTHEAST
MN/WESTERN WI THIS EVENING.

..GUYER.. 07/26/2012

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

ATTN...WFO...DVN...ARX...MPX...DMX...FSD...OAX...

LAT...LON   41799514 42629539 43059432 43979281 44159135 43839052
            43269158 42369205 41539364 41799514

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 25, 7:21 PM CDTMesoscale DiscussionSPCCass, Fremont, Mills, Montgomery, Page, Pottawattamie and 1 more54 min
Jul 25, 8:40 PM CDTMesoscale DiscussionSPCBenton, Buchanan, Cedar, Clayton, Clinton, Delaware and 17 more65 min
Jul 25, 8:57 PM CDTSevere Thunderstorm WatchSPCBenton, Buchanan, Cedar, Clinton, Delaware, Dubuque and 10 more6 hr
Jul 25, 11:34 PM CDTMesoscale DiscussionSPCCedar, Clinton, Dubuque, Jackson, Jones, Scott86 min
Jul 25, 8:28 PM CDTMesoscale DiscussionSPCBrown, Calumet, Kewaunee, Manitowoc, Sheboygan92 min
Jul 25, 11:09 PM CDTMesoscale DiscussionSPCOzaukee, Sheboygan96 min
Jul 26, 1:40 AM CDTMesoscale DiscussionSPCCalumet, Dodge, Fond du Lac, Green Lake, Jefferson, Kenosha and 8 more65 min
Jul 26, 12:09 PM CDTMesoscale DiscussionSPCAdams, Brown, Calumet, Columbia, Dane, Dodge and 27 more2 hr

Nearby

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