Alert archive / Illinois / Mesoscale Discussions in 2003

Mesoscale Discussion 638

April 30, 200316 counties in Illinois; 6 counties in Iowa; 8 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Apr 30, 2003, 11:04 AM CDT for 16 counties in Illinois; 6 counties in Iowa; 8 counties in Wisconsin. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: Apr 30, 2003, 11:04 AM CDT (16:04 UTC)
Expired: Apr 30, 2003, 1:00 PM CDT
In force: 116 min
Issued by: the Storm Prediction Center

All 30 counties

Cedar County, IA, Clinton County, IA, Dubuque County, IA, Jackson County, IA, Jones County, IA, Scott County, IA, Boone County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, Lake 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, Lafayette County, WI, Milwaukee County, WI, Racine County, WI, Rock County, WI, Walworth County, WI, Waukesha County, WI

The radar

The Quad Cities radar (KDVN), 86 km from the middle of the area, began a volume at 16:05 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 187Apr 30, 1:00 PM CDT

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 4.1 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 849 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 478 m²/s²
0-3 km storm-relative helicity: 567 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 30, 12:22 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Cass, Champaign, Christian, Coles and 37 more	113 min
Apr 30, 1:00 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Brown, Bureau, Cass, Champaign, DeWitt and 30 more	5 hr
Apr 30, 3:24 PM CDT	Mesoscale Discussion	SPC	Adams, Brown, Bureau, Cass, Champaign, DeWitt and 32 more	2 hr
Apr 30, 5:15 PM CDT	Tornado Watch	SPC	Adams, Hancock, Henderson, McDonough, Mercer, Rock Island and 2 more	6 hr
Apr 30, 5:50 PM CDT	Severe Thunderstorm Watch	SPC	Bureau, Cook, DeKalb, DuPage, Grundy, Henry and 15 more	5 hr
Apr 29, 7:00 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Boone, Carroll, Cass and 13 more	3 hr
Apr 29, 7:30 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Audubon, Boone, Carroll, Cass and 17 more	7 hr
Apr 29, 10:40 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Boone, Carroll, Cass and 17 more	2 hr
Apr 30, 2:49 PM CDT	Mesoscale Discussion	SPC	Appanoose, Clarke, Decatur, Lucas, Monroe, Page and 3 more	116 min

Nearby

Mesoscale Discussions in Illinois, 2003 Mesoscale Discussions in Wisconsin, 2003 Mesoscale Discussions in Iowa, 2003 Every mesoscale discussion in 2003

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.