Alert archive / Illinois / Mesoscale Discussions in 2005

Mesoscale Discussion 615

April 20, 200518 counties in Illinois; 6 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2005, 7:03 PM CDT for 18 counties in Illinois; 6 counties in Iowa. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: Apr 20, 2005, 7:03 PM CDT (00:03 UTC)
Expired: Apr 20, 2005, 8:30 PM CDT
In force: 87 min
Issued by: the Storm Prediction Center

All 24 counties

Des Moines County, IA, Henry County, IA, Lee County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Brown County, IL, Cass County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Knox County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, Menard County, IL, Mercer County, IL, Peoria County, IL, Rock Island County, IL, Schuyler County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL

The radar

The Quad Cities radar (KDVN), 80 km from the middle of the area, began a volume at 00:05 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, 0.1 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-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: 5 J/kg
Mixed-layer CIN: -210 J/kg
Mixed-layer LCL: 656 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 122 m²/s²
0-3 km storm-relative helicity: 233 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.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 21, 1:10 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Brown, Calhoun, Cass, Clinton, Greene and 13 more	6 hr
Apr 21, 3:28 PM CDT	Mesoscale Discussion	SPC	Adams, Monroe, Pike	92 min
Apr 21, 5:22 PM CDT	Mesoscale Discussion	SPC	Alexander, Gallatin, Hardin, Johnson, Massac, Pope and 4 more	53 min
Apr 21, 5:35 PM CDT	Severe Thunderstorm Watch	SPC	Alexander, Gallatin, Hardin, Jackson, Johnson, Massac and 5 more	7 hr
Apr 21, 5:52 PM CDT	Mesoscale Discussion	SPC	Calhoun, Jersey, Madison, Monroe, Saint Clair	53 min
Apr 21, 6:45 PM CDT	Severe Thunderstorm Watch	SPC	Bond, Calhoun, Clinton, Franklin, Greene, Hamilton and 10 more	6 hr
Apr 21, 3:34 AM CDT	Mesoscale Discussion	SPC	Adams, Fremont, Mills, Montgomery, Page, Pottawattamie and 2 more	116 min
Apr 21, 3:05 PM CDT	Mesoscale Discussion	SPC	Fremont, Mills	85 min
Apr 21, 3:35 PM CDT	Tornado Watch	SPC	Adams, Cass, Fremont, Mills, Montgomery, Page and 2 more	7 hr
Apr 21, 6:51 PM CDT	Mesoscale Discussion	SPC	Fremont, Mills, Montgomery, Page, Pottawattamie	84 min

Nearby

Mesoscale Discussions in Illinois, 2005 Mesoscale Discussions in Iowa, 2005 Every mesoscale discussion in 2005

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.