Alert archive / Iowa / Mesoscale Discussions in 2011

Mesoscale Discussion 1775

July 28, 201115 counties in Illinois; 20 counties in Iowa; 10 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2011, 5:40 PM CDT for 15 counties in Illinois; 20 counties in Iowa; 10 counties in Missouri. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued: Jul 28, 2011, 5:40 PM CDT (22:40 UTC)
Expired: Jul 28, 2011, 7:15 PM CDT
In force: 95 min
Issued by: the Storm Prediction Center

All 45 counties

Appanoose County, IA, Cedar County, IA, Clinton County, IA, Davis County, IA, Decatur County, IA, Des Moines County, IA, Henry County, IA, Jefferson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Lucas County, IA, Mahaska County, IA, Monroe County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Wapello County, IA, Washington County, IA, Wayne County, IA, Bureau County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Knox County, IL, Lee County, IL, Marshall County, IL, McDonough County, IL, Mercer County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Warren County, IL, Whiteside County, IL, Adair County, MO, Clark County, MO, Grundy County, MO, Harrison County, MO, Knox County, MO, Mercer County, MO, Putnam County, MO, Schuyler County, MO, Scotland County, MO, Sullivan County, MO

The radar

The Quad Cities radar (KDVN), 146 km from the middle of the area, began a volume at 22:40 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

Omaha, NE (KOAX), launched 12:00Z, 10.7 hours before the alert went out and 372 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: 2616 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 622 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: -127 m²/s²
0-3 km storm-relative helicity: -81 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -6.0

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
Jul 27, 7:43 PM CDT	Tornado Watch	SPC	Boone, Carroll, Cook, DeKalb, DuPage, Jo Daviess and 10 more	5 hr
Jul 27, 9:43 PM CDT	Mesoscale Discussion	SPC	Boone, Carroll, Cook, DeKalb, DuPage, Jo Daviess and 9 more	62 min
Jul 28, 12:36 AM CDT	Mesoscale Discussion	SPC	Boone, Carroll, Cook, DeKalb, DuPage, Jo Daviess and 10 more	84 min
Jul 28, 2:47 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Calhoun, Carroll, Cerro Gordo, Cherokee, Crawford and 18 more	118 min

Nearby

Mesoscale Discussions in Iowa, 2011 Mesoscale Discussions in Illinois, 2011 Mesoscale Discussions in Missouri, 2011 Every mesoscale discussion in 2011

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.