Alert archive / Illinois / Mesoscale Discussions in 2012

Mesoscale Discussion 404

April 1, 201227 counties in Illinois; Clinton County, Jackson County, Scott County, Iowa; 4 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Apr 1, 2012, 1:33 AM CDT for 27 counties in Illinois; Clinton County, Jackson County, Scott County, Iowa; 4 counties in Wisconsin. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued
Apr 1, 2012, 1:33 AM CDT (06:33 UTC)
Expired
Apr 1, 2012, 3:30 AM CDT
In force
117 min
Issued by
the Storm Prediction Center
All 34 counties

Clinton County, IA, Jackson County, IA, Scott County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, DeKalb County, IL, Fulton County, IL, Grundy County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Marshall County, IL, McHenry County, IL, McLean County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Whiteside County, IL, Winnebago County, IL, Woodford County, IL, Grant County, WI, Green County, WI, Lafayette County, WI, Rock County, WI

The radar

The Quad Cities radar (KDVN), 88 km from the middle of the area, began a volume at 06:36 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, 6.6 hours before the alert went out and 81 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 2012-04-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2012-04-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 196 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1520 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
196 m²/s²
0-3 km storm-relative helicity
306 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

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

897 
ACUS11 KWNS 010633
SWOMCD
SPC MCD 010633 
ILZ000-WIZ000-IAZ000-010830-

MESOSCALE DISCUSSION 0404
NWS STORM PREDICTION CENTER NORMAN OK
0133 AM CDT SUN APR 01 2012

AREAS AFFECTED...PORTIONS EXTREME ERN IA...CENTRAL/NRN IL...EXTREME
SRN WI.

CONCERNING...SEVERE THUNDERSTORM WATCH 124...

VALID 010633Z - 010830Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 124
CONTINUES.

CONTINUE WW ALONG AND E OF WRN FRINGES OF ELEVATED MCS.  WHILE
OVERALL THREAT WILL DIMINISH GRADUALLY THROUGH REMAINDER WW VALID
PERIOD...OCNL/SPORADIC SVR HAIL POTENTIAL WILL CONTINUE...MAINLY
WITH CELLS ON SWRN/WRN FRINGES OF PERSISTENT MCS WHERE CONVECTION
HAS RELATIVELY UNIMPEDED ACCESS TO FAVORABLE THETAE.

VWP/PROFILER DATA INDICATE TWO PRIMARY LLJ BRANCHES...STRONGEST ONE
MERIDIONALLY ORIENTED OVER CENTRAL HIGH PLAINS...SECONDARY BRANCH
WITH 30-35 KT AXIAL FLOW FROM OZARKS NEWD ACROSS CENTRAL IL. 
MEANWHILE...SFC ANALYSIS SHOWS LOW OVER NEB/IA BORDER...WARM FRONT
ESEWD OVER DSM AREA THEN SEWD ACROSS ERN FRINGES STL AREA IN IL. 
ISENTROPIC ASCENT TO LFC WILL CONTINUE NE OF SFC WARM FRONT OVER
IL/SRN WI IN SUPPORT OF CONVECTION...WHILE ISENTROPES AT LFC LEVEL
SHIFT EWD WITH TIME.  GREATEST BUOYANCY -- I.E. ELEVATED MUCAPE
AROUND 1500 J/KG -- SHOULD REMAIN ON SWRN SIDE OF COMPLEX WHERE
AVAILABLE LOW-LEVEL MOISTURE AND MIDLEVEL LAPSE RATES EACH ARE
RELATIVELY MAXIMIZED.  CAPE WILL DIMINISH NWD AND NEWD FROM
W-CENTRAL IL.  EFFECTIVE SHEAR ALSO WILL CONTINUE TO WEAKEN WITH EWD
EXTENT...PARTLY AS FUNCTION OF SHALLOWER CONVECTION-BEARING LAYERS
WITH RESPECT TO STRONGER DEEP-LAYER SHEAR.

..EDWARDS.. 04/01/2012

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

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

LAT...LON   40529059 42409073 42969073 42878899 42448835 41518813
            40568837 40178925 40529059

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 31, 8:52 PM CDTMesoscale DiscussionSPCBureau, Carroll, DeKalb, Henderson, Henry, Jo Daviess and 14 more53 min
Mar 31, 9:24 PM CDTSevere Thunderstorm WatchSPCBoone, Bureau, Carroll, DeKalb, Henry, Jo Daviess and 16 more9 hr
Apr 1, 7:56 AM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, DeKalb, Fulton, Grundy and 21 more2 hr

Nearby

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