Alert archive / Illinois / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 282
The Storm Prediction Center issued this severe thunderstorm watch at Jun 18, 2021, 9:20 PM CDT for 39 counties in Illinois. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 18, 2021, 9:20 PM CDT (02:20 UTC)
- Expired
- Jun 19, 2021, 4:00 AM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 39 counties
Cass County, IL, Champaign County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Effingham County, IL, Fayette County, IL, Fulton County, IL, Greene County, IL, Jasper County, IL, Knox County, IL, Lawrence County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Marshall County, IL, Mason County, IL, McLean County, IL, Menard County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Peoria County, IL, Piatt County, IL, Richland County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Shelby County, IL, Stark County, IL, Tazewell County, IL, Vermilion County, IL, Woodford County, IL
The radar
The Lincoln radar (KILX), 13 km from the middle of the area, began a volume at 02:22 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
- 10%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 60%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 70%
- One or more hailstones of 2 inches or more
- 50%
- Six or more combined severe hail and wind reports
- 90%
Warnings issued inside it
17 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 18, 9:44 PM CDT | Severe Thunderstorm Warning | ILX | Clark, Cumberland | 46 min |
| Jun 18, 10:24 PM CDT | Severe Thunderstorm Warning | ILX | Knox, Peoria | 36 min |
| Jun 18, 10:32 PM CDT | Severe Thunderstorm Warning | ILX | Clark, Crawford | 25 min |
| Jun 18, 11:06 PM CDT | Severe Thunderstorm Warning | ILX | Knox | 39 min |
| Jun 18, 11:29 PM CDT | Severe Thunderstorm Warning | ILX | Clark | 46 min |
| Jun 18, 11:47 PM CDT | Severe Thunderstorm Warning | ILX | Fulton, Knox, Peoria | 43 min |
| Jun 18, 11:57 PM CDT | Tornado Warning | ILX | Fulton, Knox | 33 min |
| Jun 19, 12:13 AM CDT | Severe Thunderstorm Warning | ILX | Fulton, Mason, Peoria, Tazewell | 47 min |
| Jun 19, 12:26 AM CDT | Flash Flood Warning | ILX | Clark | 6 hr |
| Jun 19, 12:28 AM CDT | Flash Flood Warning | ILX | Fulton, Knox | 5 hr |
| Jun 19, 12:52 AM CDT | Severe Thunderstorm Warning | ILX | Logan, McLean, Mason, Tazewell | 38 min |
| Jun 19, 1:19 AM CDT | Severe Thunderstorm Warning | ILX | Logan, McLean, Tazewell | 41 min |
| Jun 19, 1:23 AM CDT | Severe Thunderstorm Warning | ILX | McLean | 52 min |
| Jun 19, 1:53 AM CDT | Flash Flood Warning | ILX | Coles, Douglas, Edgar | 5 hr |
| Jun 19, 1:59 AM CDT | Severe Thunderstorm Warning | ILX | Edgar | 46 min |
| Jun 19, 2:19 AM CDT | Severe Thunderstorm Warning | ILX | McLean | 41 min |
| Jun 19, 3:29 AM CDT | Flash Flood Warning | ILX | Champaign, Douglas, Edgar, Vermilion | 3 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
Lincoln, IL (KILX), launched 00:00Z, 2.3 hours before the alert went out and 64 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
- 2124 J/kg
- Mixed-layer CIN
- -145 J/kg
- Mixed-layer LCL
- 1616 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 165 m²/s²
- 0-3 km storm-relative helicity
- 200 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 4.0
The text
As transmitted.
769
WWUS20 KWNS 190217
SEL2
SPC WW 190217
ILZ000-190900-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 282
NWS Storm Prediction Center Norman OK
920 PM CDT Fri Jun 18 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Central and Eastern Illinois
* Effective this Friday night and Saturday morning from 920 PM
until 400 AM CDT.
* Primary threats include...
Scattered large hail likely with isolated very large hail events
to 2 inches in diameter possible
Scattered damaging wind gusts to 70 mph likely
SUMMARY...Strong to severe thunderstorms are expected to develop
this evening across central to east-central/southeast Illinois, with
additional storms also potentially moving into the region late
tonight from the west. Large hail and damaging winds can be expected
with the strongest storms given the degree of instability and
moderately strong belt of west-northwesterly winds aloft.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 50 miles west northwest
of Springfield IL to 40 miles east of Mattoon IL. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU2).
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 279...WW 280...WW 281...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
29025.
...GuyerSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 18, 8:53 PM CDT | Mesoscale Discussion | SPC | Bond, Brown, Cass, Christian, Clark, Clay and 26 more | 97 min |
| Jun 18, 9:27 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Hancock, Henderson, McDonough, Mercer and 2 more | 2 hr |
| Jun 18, 10:08 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Brown, Bureau, Hancock, Henderson, Henry and 6 more | 8 hr |
| Jun 19, 2:10 AM CDT | Mesoscale Discussion | SPC | Adams, Brown, Cass, Champaign, Christian, Clark and 27 more | 2 hr |
| Jun 19, 11:15 AM CDT | Mesoscale Discussion | SPC | Effingham, Fayette, Greene, Macoupin, Montgomery, Morgan and 1 more | 2 hr |
| Jun 19, 2:12 PM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Clinton, Greene, Jersey, Macoupin and 7 more | 93 min |
| Jun 19, 2:43 PM CDT | Severe Thunderstorm Watch | SPC | Bond, Calhoun, Clinton, Fayette, Greene, Jersey and 9 more | 7 hr |
| Jun 19, 5:11 PM CDT | Mesoscale Discussion | SPC | Calhoun, Clinton, Greene, Jersey, Macoupin, Madison and 6 more | 64 min |
Nearby
Severe Thunderstorm Watches in Illinois, 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.