Alert archive / Iowa / Mesoscale Discussions in 2025

Mesoscale Discussion 1639

July 11, 2025Mercer County, Rock Island County, Illinois; 23 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Jul 11, 2025, 12:44 AM CDT for Mercer County, Rock Island County, Illinois; 23 counties in Iowa. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued
Jul 11, 2025, 12:44 AM CDT (05:44 UTC)
Expired
Jul 11, 2025, 2:15 AM CDT
In force
91 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 503
All 25 counties

Cedar County, IA, Clarke County, IA, Dallas County, IA, Des Moines County, IA, Henry County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Louisa County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Monroe County, IA, Muscatine County, IA, Polk County, IA, Poweshiek County, IA, Scott County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Mercer County, IL, Rock Island County, IL

The radar

The Des Moines radar (KDMX), 130 km from the middle of the area, began a volume at 05:45 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.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 5.7 hours before the alert went out and 147 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 2025-07-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2407 joules per kilogram.LCLEL10008507005003002001001 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 2025-07-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 91 square meters per square second.193958Sfc1 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
2407 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
1108 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
91 m²/s²
0-3 km storm-relative helicity
194 m²/s²
Significant tornado parameter
1.8
Supercell composite
12.9

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 10, 10:36 PM CDTMesoscale DiscussionSPCBureau, Ford, Grundy, Henry, Kankakee, LaSalle and 6 more114 min
Jul 11, 1:17 AM CDTSevere Thunderstorm WatchSPCHenderson, Mercer, Rock Island, Warren3 hr
Jul 11, 2:43 AM CDTMesoscale DiscussionSPCMercer, Rock Island92 min
Jul 11, 12:18 PM CDTMesoscale DiscussionSPCAdams, Bureau, Carroll, Fulton, Hancock, Henderson and 14 more87 min
Jul 11, 12:54 PM CDTTornado WatchSPCBureau, Carroll, Hancock, Henderson, Henry, Jo Daviess and 7 more7 hr
Jul 11, 2:01 PM CDTMesoscale DiscussionSPCAdams, Brown, Cass, Greene, Morgan, Pike and 1 more89 min
Jul 11, 2:19 PM CDTSevere Thunderstorm WatchSPCAdams, Brown, Pike8 hr
Jul 11, 3:53 PM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, Henderson, Henry, Jo Daviess and 8 more97 min
Jul 11, 4:51 PM CDTTornado WatchSPCBoone, Cook, DeKalb, DuPage, Grundy, Kane and 8 more5 hr
Jul 11, 5:57 PM CDTMesoscale DiscussionSPCBoone, DeKalb, DuPage, Kane, Lake, Lee and 3 more2 hr
Jul 10, 7:46 PM CDTSevere Thunderstorm WatchSPCAdair, Adams, Appanoose, Audubon, Boone, Carroll and 33 more8 hr
Jul 10, 10:51 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Boone, Carroll, Cass and 18 more114 min
Jul 11, 1:13 PM CDTSevere Thunderstorm WatchSPCBlack Hawk, Boone, Bremer, Buchanan, Butler, Clayton and 11 more7 hr

Nearby

Mesoscale Discussions in Iowa, 2025Mesoscale Discussions in Illinois, 2025Every mesoscale discussion in 2025

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.