Alert archive / Illinois / Mesoscale Discussions in 2012

Mesoscale Discussion 538

April 14, 201218 counties in Illinois; 7 counties in Iowa; 4 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Apr 14, 2012, 9:54 PM CDT for 18 counties in Illinois; 7 counties in Iowa; 4 counties in Wisconsin. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued
Apr 14, 2012, 9:54 PM CDT (02:54 UTC)
Expired
Apr 14, 2012, 11:30 PM CDT
In force
96 min
Issued by
the Storm Prediction Center
All 29 counties

Cedar County, IA, Clinton County, IA, Jackson County, IA, Jones County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, DeKalb County, IL, DuPage County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Rock Island County, IL, Stephenson County, IL, Whiteside County, IL, Winnebago County, IL, Green County, WI, Kenosha County, WI, Rock County, WI, Walworth County, WI

The radar

The Quad Cities radar (KDVN), 91 km from the middle of the area, began a volume at 02:58 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

Davenport, (KDVN), launched 00:00Z, 2.9 hours before the alert went out and 84 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, Davenport, at 00:00Z on 2012-04-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 300 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, Davenport, at 00:00Z on 2012-04-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 124 square meters per square second.1939587897Sfc1 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
300 J/kg
Mixed-layer CIN
-50 J/kg
Mixed-layer LCL
726 m above ground
0-6 km bulk shear
69 kt
0-1 km storm-relative helicity
124 m²/s²
0-3 km storm-relative helicity
126 m²/s²
Significant tornado parameter
0.2
Supercell composite
1.0

Open this sounding in Storm Lab

The text

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

287 
ACUS11 KWNS 150255
SWOMCD
SPC MCD 150254
ILZ000-WIZ000-IAZ000-150430-

MESOSCALE DISCUSSION 0538
NWS STORM PREDICTION CENTER NORMAN OK
0954 PM CDT SAT APR 14 2012

AREAS AFFECTED...NRN IL AND PARTS OF SRN WI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 150254Z - 150430Z

CONVECTIVE TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF AN
ADDITIONAL WW EAST OF WW 172 WITHIN THE NEXT HOUR OR TWO.

THE ENVIRONMENT ALONG/NORTH OF A DEVELOPING WARM FRONT ACROSS
NORTHERN ILLINOIS DOES NOT APPEAR MUCH MORE THAN WEAKLY UNSTABLE.
HOWEVER...A SIGNIFICANT AND PERSISTENT SURFACE PRESSURE PERTURBATION
REMAINS EVIDENT WITH THE ORGANIZED MESOSCALE CONVECTIVE SYSTEM NOW
IN THE PROCESS OF DEVELOPING EASTWARD ACROSS EASTERN IOWA INTO
NORTHERN ILLINOIS AND EXTREME SOUTHERN WISCONSIN.  ACTIVITY IS BEING
SUPPORTED BY AN AREA OF ENHANCED LOWER/MID TROPOSPHERIC WARM
ADVECTION AND DIVERGENT UPPER FLOW DOWNSTREAM OF THE SIGNIFICANT
UPPER TROUGH CROSSING THE ROCKIES.  AND IT APPEAR THAT CONVECTION
MAY MAINTAIN STRENGTH WITH THE RISK FOR POTENTIALLY DAMAGING WIND
GUSTS...PERHAPS A CONTINUING RISK FOR HAIL...INTO THE
CHICAGO...POSSIBLY MILWAUKEE...METROPOLITAN AREAS BY THE 06-08Z TIME
FRAME.

..KERR.. 04/15/2012

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

ATTN...WFO...LOT...ILX...MKX...DVN...

LAT...LON   42199117 42589015 42768913 42798804 42538779 41788770
            41418816 41208899 41239018 41229086 41179144 42199117

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 14, 8:41 PM CDTSevere Thunderstorm WatchSPCBureau, Carroll, Henderson, Henry, Mercer, Putnam and 3 more4 hr
Apr 15, 4:22 PM CDTMesoscale DiscussionSPCBond, Brown, Calhoun, Cass, Christian, Clinton and 31 more83 min
Apr 15, 4:42 PM CDTTornado WatchSPCAdams, Bond, Brown, Calhoun, Cass, Clinton and 15 more6 hr
Apr 15, 6:12 PM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, Cook, DeKalb, DuPage and 25 more63 min
Apr 14, 7:50 PM CDTMesoscale DiscussionSPCBenton, Buchanan, Cedar, Delaware, Henry, Iowa and 13 more55 min
Apr 14, 7:51 PM CDTMesoscale DiscussionSPCCherokee, Ida, Lyon, Monona, O'Brien, Osceola and 3 more84 min
Apr 14, 10:09 PM CDTSevere Thunderstorm WatchSPCFremont, Harrison, Mills, Monona, Montgomery, Page and 3 more6 hr
Apr 14, 11:28 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Audubon, Boone, Carroll and 28 more92 min
Apr 15, 3:25 AM CDTMesoscale DiscussionSPCAdams, Audubon, Cass, Fremont, Harrison, Mills and 5 more95 min
Apr 15, 1:56 PM CDTMesoscale DiscussionSPCAudubon, Boone, Buena Vista, Butler, Calhoun, Carroll and 28 more94 min
Apr 15, 3:37 PM CDTTornado WatchSPCCerro Gordo, Chickasaw, Clay, Dickinson, Emmet, Floyd and 8 more7 hr
Apr 15, 5:54 PM CDTMesoscale DiscussionSPCDunn, Pierce, Polk, Saint Croix96 min

Nearby

Mesoscale Discussions in Illinois, 2012Mesoscale Discussions in Iowa, 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.