Alert archive / Indiana / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 400
The Storm Prediction Center issued this severe thunderstorm watch at Jul 29, 2021, 1:00 AM CDT for 24 counties in Illinois; 26 counties in Indiana; 7 counties in Michigan. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 29, 2021, 1:00 AM CDT (06:00 UTC)
- Expired
- Jul 29, 2021, 6:12 AM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 65 kt
All 57 counties
Boone County, IL, Bureau County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Jo Daviess County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, McHenry County, IL, Ogle County, IL, Putnam County, IL, Stephenson County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Adams County, IN, Allen County, IN, Benton County, IN, Cass County, IN, DeKalb County, IN, Elkhart County, IN, Fulton County, IN, Huntington County, IN, Jasper County, IN, Kosciusko County, IN, LaGrange County, IN, Lake County, IN, LaPorte County, IN, Marshall County, IN, Miami County, IN, Newton County, IN, Noble County, IN, Porter County, IN, Pulaski County, IN, Saint Joseph County, IN, Starke County, IN, Steuben County, IN, Wabash County, IN, Wells County, IN, White County, IN, Whitley County, IN, Allegan County, MI, Berrien County, MI, Branch County, MI, Cass County, MI, Kalamazoo County, MI, Saint Joseph County, MI, Van Buren County, MI
The radar
The Chicago radar (KLOT), 73 km from the middle of the area, began a volume at 05:59 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 20%
- One or more EF2 to EF5 tornadoes
- 10%
- Ten or more severe wind reports
- 70%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
13 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 29, 1:23 AM CDT | Severe Thunderstorm Warning | LOT | Boone, McHenry, Winnebago | 82 min |
| Jul 29, 1:30 AM CDT | Severe Thunderstorm Warning | DVN | Jo Daviess, Stephenson | 60 min |
| Jul 29, 1:49 AM CDT | Severe Thunderstorm Warning | LOT | Lake, McHenry | 71 min |
| Jul 29, 2:14 AM CDT | Severe Thunderstorm Warning | LOT | Cook, DeKalb, DuPage, Kane | 76 min |
| Jul 29, 2:58 AM CDT | Severe Thunderstorm Warning | LOT | Cook, Grundy, Kendall, Will | 77 min |
| Jul 29, 3:05 AM CDT | Severe Thunderstorm Warning | GRR | Allegan, Ottawa, Van Buren | 55 min |
| Jul 29, 3:09 AM CDT | Severe Thunderstorm Warning | IWX | Berrien, Cass | 36 min |
| Jul 29, 3:23 AM CDT | Severe Thunderstorm Warning | IWX | Elkhart, Kosciusko, LaPorte, Marshall, Saint Joseph | 52 min |
| Jul 29, 3:45 AM CDT | Severe Thunderstorm Warning | LOT | Kankakee | 60 min |
| Jul 29, 3:47 AM CDT | Severe Thunderstorm Warning | GRR | Allegan, Barry, Calhoun, Kalamazoo, Van Buren | 58 min |
| Jul 29, 3:59 AM CDT | Severe Thunderstorm Warning | IWX | Elkhart, Kosciusko, Marshall, Noble, Saint Joseph | 46 min |
| Jul 29, 4:25 AM CDT | Severe Thunderstorm Warning | IWX | Allen, DeKalb, Kosciusko, Noble, Whitley | 50 min |
| Jul 29, 5:07 AM CDT | Severe Thunderstorm Warning | IWX | Allen, DeKalb | 38 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Lincoln, IL (KILX), launched 00:00Z, 6.0 hours before the alert went out and 205 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
- 332 J/kg
- Mixed-layer CIN
- -288 J/kg
- Mixed-layer LCL
- 1661 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 57 m²/s²
- 0-3 km storm-relative helicity
- 101 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
965
WWUS20 KWNS 290558
SEL0
SPC WW 290558
ILZ000-INZ000-MIZ000-LMZ000-291300-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 400
NWS Storm Prediction Center Norman OK
100 AM CDT Thu Jul 29 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Northern Illinois
Northern Indiana
Southwestern Lower Michigan
Lake Michigan
* Effective this Thursday morning from 100 AM until 800 AM CDT.
* Primary threats include...
Scattered damaging winds likely with isolated significant gusts
to 75 mph possible
Isolated large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...A quasi-linear convective system, with embedded severe
thunderstorms (including a supercell or two) will proceed
southeastward from Wisconsin across the watch area. Some eastward
pivot or growth of this activity toward southwestern MI also is
possible. Severe gusts will be the main concern, though the threat
exists for an embedded tornado or two, as well as isolated hail.
The severe thunderstorm watch area is approximately along and 110
statute miles east and west of a line from 40 miles east northeast
of Rockford IL to 65 miles south southeast of Valparaiso IN. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU0).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 399...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
32035.
...EdwardsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 29, 12:32 AM CDT | Mesoscale Discussion | SPC | Boone, Carroll, Cook, DeKalb, DuPage, Grundy and 11 more | 88 min |
| Jul 29, 1:34 AM CDT | Mesoscale Discussion | SPC | Boone, Cook, DeKalb, DuPage, Kane, Kendall and 3 more | 86 min |
| Jul 29, 3:18 AM CDT | Mesoscale Discussion | SPC | Cook, DeKalb, DuPage, Grundy, Iroquois, Kankakee and 4 more | 87 min |
| Jul 29, 2:19 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Cass, Champaign, Christian, Clark and 34 more | 116 min |
| Jul 29, 4:55 AM CDT | Mesoscale Discussion | SPC | Adams, Allen, Blackford, DeKalb, Grant, Huntington and 6 more | 95 min |
| Jul 29, 2:13 PM CDT | Severe Thunderstorm Watch | SPC | Dearborn, Fayette, Franklin, Ohio, Ripley, Switzerland and 2 more | 7 hr |
| Jul 29, 5:34 PM CDT | Mesoscale Discussion | SPC | Dearborn, Fayette, Franklin, Henry, Rush, Union and 1 more | 116 min |
Nearby
Severe Thunderstorm Watches in Indiana, 2021Severe Thunderstorm Watches in Illinois, 2021Severe Thunderstorm Watches in Michigan, 2021Every severe thunderstorm watch 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.