Alert archive / Illinois / Tornado Watches in 2020
Tornado Watch 207
The Storm Prediction Center issued this tornado watch at May 23, 2020, 12:33 PM CDT for 4 states. It was in force for 8 hr.
The area
The outline as issued.
The facts
- Issued
- May 23, 2020, 12:33 PM CDT (17:33 UTC)
- Expired
- May 23, 2020, 9:00 PM CDT
- In force
- 8 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 76 counties
Allamakee County, IA, Buchanan County, IA, Cedar County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Fayette County, IA, Jackson County, IA, Johnson County, IA, Jones County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DeWitt County, IL, DuPage County, IL, Ford County, IL, Fulton County, IL, Grundy County, IL, Henderson County, IL, Henry County, IL, Iroquois County, IL, Jo Daviess County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McHenry County, IL, McLean County, IL, Mercer County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Warren County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Woodford County, IL, Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN, Crawford County, WI, Dane County, WI, Grant County, WI, Green County, WI, Iowa County, WI, Jefferson County, WI, Kenosha County, WI, Lafayette County, WI, Milwaukee County, WI, Racine County, WI, Richland County, WI, Rock County, WI, Walworth County, WI, Waukesha County, WI
The radar
The Chicago radar (KLOT), 106 km from the middle of the area, began a volume at 17:33 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
- 80%
- One or more EF2 to EF5 tornadoes
- 30%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
55 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 23, 12:39 PM CDT | Tornado Warning | DVN | Cedar, Clinton | 51 min |
| May 23, 12:50 PM CDT | Tornado Warning | DVN | Cedar, Jones | 40 min |
| May 23, 12:53 PM CDT | Severe Thunderstorm Warning | ILX | Tazewell, Woodford | 52 min |
| May 23, 12:59 PM CDT | Tornado Warning | DVN | Henry, Rock Island, Whiteside | 46 min |
| May 23, 1:17 PM CDT | Tornado Warning | DVN | Clinton, Jackson | 43 min |
| May 23, 1:18 PM CDT | Severe Thunderstorm Warning | DVN | Bureau, Putnam | 27 min |
| May 23, 1:18 PM CDT | Tornado Warning | DVN | Cedar, Jones | 18 min |
| May 23, 1:29 PM CDT | Severe Thunderstorm Warning | ILX | McLean, Tazewell, Woodford | 46 min |
| May 23, 1:29 PM CDT | Tornado Warning | DVN | Jones | 16 min |
| May 23, 1:33 PM CDT | Severe Thunderstorm Warning | LOT | Ogle | 42 min |
| May 23, 1:40 PM CDT | Tornado Warning | DVN | Carroll, Whiteside | 5 min |
| May 23, 1:50 PM CDT | Severe Thunderstorm Warning | DVN | Carroll, Whiteside | 55 min |
| May 23, 1:54 PM CDT | Tornado Warning | DVN | Jackson | 38 min |
| May 23, 1:57 PM CDT | Tornado Warning | ILX | Woodford | 20 min |
| May 23, 2:02 PM CDT | Tornado Warning | LOT | Livingston | 43 min |
| May 23, 2:07 PM CDT | Severe Thunderstorm Warning | LOT | Ogle | 23 min |
| May 23, 2:08 PM CDT | Severe Thunderstorm Warning | LOT | Grundy, Kendall, LaSalle | 67 min |
| May 23, 2:17 PM CDT | Tornado Warning | DVN | Bureau, Henry, Whiteside | 23 min |
| May 23, 2:26 PM CDT | Severe Thunderstorm Warning | LOT | Ogle, Winnebago | 64 min |
| May 23, 2:27 PM CDT | Tornado Warning | DVN | Carroll, Whiteside | 36 min |
| May 23, 2:27 PM CDT | Tornado Warning | DVN | Jo Daviess | 34 min |
| May 23, 2:37 PM CDT | Tornado Warning | LOT | Livingston | 53 min |
| May 23, 2:39 PM CDT | Severe Thunderstorm Warning | LOT | Grundy, Kendall, Will | 51 min |
| May 23, 2:44 PM CDT | Severe Thunderstorm Warning | LOT | Ogle | 46 min |
| May 23, 3:02 PM CDT | Tornado Warning | LOT | Cook, Will | 43 min |
| May 23, 3:05 PM CDT | Tornado Warning | DVN | Jo Daviess | 27 min |
| May 23, 3:09 PM CDT | Severe Thunderstorm Warning | LOT | Boone, Winnebago | 66 min |
| May 23, 3:14 PM CDT | Tornado Warning | LOT | Winnebago | 61 min |
| May 23, 3:16 PM CDT | Tornado Warning | ARX | Grant | 44 min |
| May 23, 3:23 PM CDT | Severe Thunderstorm Warning | MKX | Rock | 52 min |
| May 23, 3:27 PM CDT | Severe Thunderstorm Warning | LOT | Ford, Iroquois, Kankakee, Livingston | 48 min |
| May 23, 3:48 PM CDT | Severe Thunderstorm Warning | LOT | Will | 42 min |
| May 23, 3:50 PM CDT | Tornado Warning | LOT | Ford, Iroquois | 17 min |
| May 23, 3:55 PM CDT | Severe Thunderstorm Warning | LOT | Cook | 50 min |
| May 23, 3:56 PM CDT | Tornado Warning | ARX | Grant | 35 min |
| May 23, 4:02 PM CDT | Severe Thunderstorm Warning | DVN | Carroll, Jo Daviess, Stephenson | 58 min |
| May 23, 4:04 PM CDT | Tornado Warning | MKX | Rock | 25 min |
| May 23, 4:09 PM CDT | Severe Thunderstorm Warning | LOT | Ford, Iroquois, Kankakee | 36 min |
| May 23, 4:13 PM CDT | Severe Thunderstorm Warning | LOT | Ford, Iroquois | 62 min |
| May 23, 4:16 PM CDT | Severe Thunderstorm Warning | LOT | Kankakee | 44 min |
| May 23, 4:19 PM CDT | Tornado Warning | DVN | Jo Daviess | 11 min |
| May 23, 4:23 PM CDT | Severe Thunderstorm Warning | LOT | Lake, Porter | 56 min |
| May 23, 4:23 PM CDT | Tornado Warning | MKX | Lafayette | 35 min |
| May 23, 4:28 PM CDT | Severe Thunderstorm Warning | MKX | Rock | 47 min |
| May 23, 4:50 PM CDT | Tornado Warning | MKX | Rock | 40 min |
| May 23, 4:53 PM CDT | Flash Flood Warning | LOT | Cook | 6 hr |
| May 23, 5:15 PM CDT | Tornado Warning | MKX | Rock | 31 min |
| May 23, 5:29 PM CDT | Severe Thunderstorm Warning | LOT | Porter | 31 min |
| May 23, 5:39 PM CDT | Flash Flood Warning | MKX | Rock | 3 hr |
| May 23, 6:04 PM CDT | Severe Thunderstorm Warning | LOT | Boone, DeKalb, Kane, McHenry | 56 min |
| May 23, 6:13 PM CDT | Tornado Warning | LOT | DeKalb, Kane, McHenry | 47 min |
| May 23, 6:42 PM CDT | Severe Thunderstorm Warning | LOT | Will | 48 min |
| May 23, 6:57 PM CDT | Severe Thunderstorm Warning | LOT | Cook, Kane, Lake, McHenry | 79 min |
| May 23, 7:33 PM CDT | Severe Thunderstorm Warning | LOT | Lake, Porter | 72 min |
| May 23, 8:06 PM CDT | Flash Flood Warning | LOT | Porter | 4 hr |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Davenport, (KDVN), launched 12:00Z, 5.6 hours before the alert went out and 116 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
- 145 J/kg
- Mixed-layer CIN
- -133 J/kg
- Mixed-layer LCL
- 859 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 148 m²/s²
- 0-3 km storm-relative helicity
- 198 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
As transmitted.
728
WWUS20 KWNS 231730
SEL7
SPC WW 231730
IAZ000-ILZ000-INZ000-WIZ000-LMZ000-240100-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 207
NWS Storm Prediction Center Norman OK
1235 PM CDT Sat May 23 2020
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Eastern Iowa
Northern Illinois
Northwest Indiana
Southern Wisconsin
Lake Michigan
* Effective this Saturday afternoon and evening from 1235 PM
until 800 PM CDT.
* Primary threats include...
Several tornadoes likely with a couple intense tornadoes
possible
Scattered damaging wind gusts to 70 mph possible
Scattered large hail events to 1.5 inches in diameter possible
SUMMARY...Scattered thunderstorms are beginning to form across
eastern Iowa and northwest Illinois. These storms will persist
through the afternoon and track northeastward across the watch area.
The strongest cells will pose a risk of tornadoes, damaging winds,
and hail.
The tornado watch area is approximately along and 115 statute miles
east and west of a line from 60 miles north northeast of Dubuque IA
to 10 miles southeast of Bloomington IL. For a complete depiction of
the watch see the associated watch outline update (WOUS64 KWNS
WOU7).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and 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.
&&
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 24035.
...HartSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 23, 11:29 AM CDT | Mesoscale Discussion | SPC | Bureau, Carroll, Cass, DeWitt, Fulton, Henderson and 24 more | 2 hr |
| May 23, 2:51 PM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Carroll, Champaign, Cook, DeKalb and 32 more | 84 min |
| May 23, 3:14 PM CDT | Mesoscale Discussion | SPC | Bartholomew, Brown, Dearborn, Decatur, Fayette, Franklin and 11 more | 61 min |
| May 23, 4:57 PM CDT | Tornado Watch | SPC | Cass, Fulton, LaPorte, Marshall, Miami, Pulaski and 3 more | 4 hr |
Nearby
Tornado Watches in Illinois, 2020Tornado Watches in Iowa, 2020Tornado Watches in Wisconsin, 2020Every tornado watch in 2020
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.