Alert archive / Illinois / Severe Thunderstorm Watches in 2018
Severe Thunderstorm Watch 67
The Storm Prediction Center issued this severe thunderstorm watch at May 2, 2018, 10:51 PM CDT for 29 counties in Illinois; 5 counties in Indiana. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- May 2, 2018, 10:51 PM CDT (03:51 UTC)
- Expired
- May 3, 2018, 3:07 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 34 counties
Cass County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Ford County, IL, Fulton County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Marshall County, IL, Mason County, IL, McLean County, IL, Menard County, IL, Morgan County, IL, Peoria County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Tazewell County, IL, Will County, IL, Woodford County, IL, Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN
The radar
The Chicago radar (KLOT), 87 km from the middle of the area, began a volume at 03:51 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
- 5%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 20%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 50%
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, 3.9 hours before the alert went out and 121 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
- 1056 J/kg
- Mixed-layer CIN
- -2 J/kg
- Mixed-layer LCL
- 1699 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 109 m²/s²
- 0-3 km storm-relative helicity
- 134 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 3.7
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 2, 7:21 PM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 24 more | 84 min |
| May 2, 10:01 PM CDT | Mesoscale Discussion | SPC | Bureau, DeKalb, DuPage, Grundy, Henderson, Henry and 18 more | 89 min |
| May 2, 10:20 PM CDT | Mesoscale Discussion | SPC | Adams, Calhoun, Pike | 115 min |
| May 2, 11:09 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Brown, Calhoun, Greene, Jersey, Macoupin and 5 more | 7 hr |
| May 3, 1:57 AM CDT | Mesoscale Discussion | SPC | Bureau, Cook, DeKalb, DeWitt, DuPage, Ford and 22 more | 93 min |
| May 3, 2:32 AM CDT | Mesoscale Discussion | SPC | Calhoun, Greene, Jersey, Macoupin, Madison, Monroe and 3 more | 88 min |
Nearby
Severe Thunderstorm Watches in Illinois, 2018Severe Thunderstorm Watches in Indiana, 2018Every severe thunderstorm watch in 2018
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.