Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 1595
The Storm Prediction Center issued this mesoscale discussion at Aug 24, 2021, 5:10 PM CDT for 13 counties in Illinois; 13 counties in Iowa. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 24, 2021, 5:10 PM CDT (22:10 UTC)
- Expired
- Aug 24, 2021, 7:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 461...462
All 26 counties
Benton County, IA, Cedar County, IA, Clinton County, IA, Iowa County, IA, Jackson County, IA, Jasper County, IA, Johnson County, IA, Jones County, IA, Linn County, IA, Muscatine County, IA, Poweshiek County, IA, Scott County, IA, Tama County, IA, Boone County, IL, Carroll County, IL, DeKalb County, IL, DuPage County, IL, Jo Daviess County, IL, Kane County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Rock Island County, IL, Stephenson County, IL, Whiteside County, IL, Winnebago County, IL
The radar
The Quad Cities radar (KDVN), 42 km from the middle of the area, began a volume at 22:12 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 12:00Z, 10.2 hours before the alert went out and 43 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.
- Mixed-layer CAPE
- 1809 J/kg
- Mixed-layer CIN
- -127 J/kg
- Mixed-layer LCL
- 1284 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- 35 m²/s²
- 0-3 km storm-relative helicity
- 9 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
154 ACUS11 KWNS 242210 SWOMCD SPC MCD 242210 ILZ000-IAZ000-250015- Mesoscale Discussion 1595 NWS Storm Prediction Center Norman OK 0510 PM CDT Tue Aug 24 2021 Areas affected...IA...northern IL Concerning...Severe Thunderstorm Watch 461...462... Valid 242210Z - 250015Z The severe weather threat for Severe Thunderstorm Watch 461, 462 continues. SUMMARY...Damaging winds, and perhaps some hail, are expected with thunderstorms this evening. DISCUSSION...Early-day thunderstorm clusters that spread over MN/WI have generated substantial convective outflow that has surged south into northern IL. Thunderstorms are gradually increasing just north of this boundary near the WI/IL border which should aid a slow southward movement this evening. Additionally, two strong/severe line segments have evolved over eastern IA and this activity is moving southeast at roughly 35kt. Given the strength of this convection, it appears organized thunderstorm clusters will spread across the remainder of northern IL toward southern Lake MI over the next several hours. Strongest winds will likely be noted with any northeast-southwest oriented bow-type structures along the line. ..Darrow.. 08/24/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...DVN...DMX... LAT...LON 42389237 42448795 41768773 41359022 41639315 42389237
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 24, 6:00 AM CDT | Mesoscale Discussion | SPC | Jo Daviess | 90 min |
| Aug 24, 1:52 PM CDT | Severe Thunderstorm Watch | SPC | Carroll, Jo Daviess, Rock Island, Stephenson, Whiteside | 5 hr |
| Aug 24, 3:09 PM CDT | Mesoscale Discussion | SPC | Boone, McHenry, Ogle, Stephenson, Winnebago | 66 min |
| Aug 24, 3:55 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Cook, DeKalb, DuPage, Kane, Lake and 4 more | 5 hr |
| Aug 24, 12:44 PM CDT | Mesoscale Discussion | SPC | Allamakee, Bremer, Butler, Chickasaw, Clayton, Fayette and 4 more | 91 min |
Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Iowa, 2021Every mesoscale discussion in 2021
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.