Alert archive / Illinois / Mesoscale Discussions in 2004

Mesoscale Discussion 2024

August 17, 200444 counties in Illinois; 9 counties in Iowa; 16 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Aug 17, 2004, 12:57 PM CDT for 44 counties in Illinois; 9 counties in Iowa; 16 counties in Missouri. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued
Aug 17, 2004, 12:57 PM CDT (17:57 UTC)
Expired
Aug 17, 2004, 2:00 PM CDT
In force
63 min
Issued by
the Storm Prediction Center
All 69 counties

Clinton County, IA, Davis County, IA, Des Moines County, IA, Henry County, IA, Lee County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Adams County, IL, Brown County, IL, Bureau County, IL, Calhoun County, IL, Carroll County, IL, Cass County, IL, Christian County, IL, DeKalb County, IL, DeWitt County, IL, Fulton County, IL, Greene County, IL, Grundy County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Jersey County, IL, Kane County, IL, Kendall County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Mercer County, IL, Morgan County, IL, Peoria County, IL, Pike County, IL, Putnam County, IL, Rock Island County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL, Whiteside County, IL, Woodford County, IL, Adair County, MO, Audrain County, MO, Clark County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Macon County, MO, Marion County, MO, Monroe County, MO, Montgomery County, MO, Pike County, MO, Ralls County, MO, Randolph County, MO, Schuyler County, MO, Scotland County, MO, Shelby County, MO

The radar

The Lincoln radar (KILX), 119 km from the middle of the area, began a volume at 18:01 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 12:00Z, 6.0 hours before the alert went out and 138 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 12:00Z on 2004-08-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 604 joules per kilogram.LCLLFCEL10008507005003002001001 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 12:00Z on 2004-08-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 111 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
604 J/kg
Mixed-layer CIN
-78 J/kg
Mixed-layer LCL
823 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
111 m²/s²
0-3 km storm-relative helicity
158 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.

IssuedProductOfficeCountiesLasted
Aug 17, 1:20 PM CDTSevere Thunderstorm WatchSPCAdams, Brown, Bureau, Calhoun, Cass, Champaign and 41 more6 hr
Aug 17, 3:59 PM CDTMesoscale DiscussionSPCAdams, Brown, Bureau, Calhoun, Cass, Champaign and 41 more61 min
Aug 17, 5:57 PM CDTMesoscale DiscussionSPCCalhoun, Cass, Champaign, Christian, DeWitt, Douglas and 19 more93 min
Aug 16, 8:54 PM CDTMesoscale DiscussionSPCAudubon, Boone, Calhoun, Carroll, Crawford, Dallas and 30 more2 hr
Aug 17, 5:04 PM CDTMesoscale DiscussionSPCBates, Cass, Henry, Jackson, Johnson, Lafayette and 1 more116 min

Nearby

Mesoscale Discussions in Illinois, 2004Mesoscale Discussions in Missouri, 2004Mesoscale Discussions in Iowa, 2004Every mesoscale discussion in 2004

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.