Alert archive / Wisconsin / Mesoscale Discussions in 2021
Mesoscale Discussion 1290
The Storm Prediction Center issued this mesoscale discussion at Jul 14, 2021, 9:15 PM CDT for 5 counties in Illinois; 8 counties in Iowa; 10 counties in Wisconsin. It was in force for 90 min.
The area
The outline as issued.
The facts
- Issued
- Jul 14, 2021, 9:15 PM CDT (02:15 UTC)
- Expired
- Jul 14, 2021, 10:45 PM CDT
- In force
- 90 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 379
All 23 counties
Allamakee County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Jackson County, IA, Jones County, IA, Linn County, IA, Carroll County, IL, Jo Daviess County, IL, Ogle County, IL, Stephenson County, IL, Winnebago County, IL, Columbia County, WI, Crawford County, WI, Dane County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Lafayette County, WI, Richland County, WI, Rock County, WI, Sauk County, WI
The radar
The Quad Cities radar (KDVN), 98 km from the middle of the area, began a volume at 02:17 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, 2.3 hours before the alert went out and 98 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
- 2569 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 832 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 253 m²/s²
- 0-3 km storm-relative helicity
- 346 m²/s²
- Significant tornado parameter
- 3.2
- Supercell composite
- 23.4
The text
As transmitted.
900 ACUS11 KWNS 150215 SWOMCD SPC MCD 150215 WIZ000-ILZ000-IAZ000-MNZ000-150345- Mesoscale Discussion 1290 NWS Storm Prediction Center Norman OK 0915 PM CDT Wed Jul 14 2021 Areas affected...Eastern IA...Southern WI...Northwest IL Concerning...Tornado Watch 379... Valid 150215Z - 150345Z The severe weather threat for Tornado Watch 379 continues. SUMMARY...Severe threat will gradually shift southeast across ww379 this evening. DISCUSSION...LLJ has strengthened considerably across eastern IA into southeastern WI this evening, where 40kt is currently observed at 1km AGL. This has aided the northward advancement of the surface front which is now draped from Lake County IL-north of RYV-north of MSN. Overall, convective trends have become more multi-clustered with an expanding corridor of thunderstorms extending southwest-northeast along the LLJ axis. A few supercells remain along the southwestern flank of this activity, especially just north of Cedar Rapids. This southern activity remains concentrated in the greater buoyancy air mass, and latest diagnostic data suggests the immediate downstream environment remains favorable for surface-based supercells (temperatures holding near 80F at DVN). Latest trends suggest the SW/NE-oriented band of storms will gradually sag southeast across the remainder of ww379 later this evening, eventually spreading across the remainder of northern IL later tonight as LLJ translates downstream. Greatest short-term severe threat appears to be in the CID-DBQ corridor where surface-based supercells continue. ..Darrow.. 07/15/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...MKX...DVN...ARX... LAT...LON 41749171 43469172 43628902 41908901 41749171
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 14, 11:17 PM CDT | Mesoscale Discussion | SPC | Boone, Carroll, DeKalb, Henry, Lee, McHenry and 6 more | 58 min |
| Jul 14, 11:57 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Bureau, DeKalb, Grundy, Henry, Kane and 7 more | 3 hr |
| Jul 15, 2:14 AM CDT | Mesoscale Discussion | SPC | Boone, Bureau, DeKalb, DuPage, Grundy, Kane and 12 more | 61 min |
| Jul 15, 1:39 PM CDT | Mesoscale Discussion | SPC | Brown, Cass, Champaign, Christian, Coles, DeWitt and 24 more | 2 hr |
| Jul 14, 8:35 PM CDT | Mesoscale Discussion | SPC | Benton, Black Hawk, Buchanan, Fayette, Grundy, Jasper and 5 more | 25 min |
Nearby
Mesoscale Discussions in Wisconsin, 2021Mesoscale Discussions in Iowa, 2021Mesoscale Discussions in Illinois, 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.