Alert archive / Illinois / Tornado Watches in 2013
Tornado Watch 122
The Storm Prediction Center issued this tornado watch at Apr 18, 2013, 5:42 AM CDT for 12 counties in Illinois; 10 counties in Missouri. It was in force for 8 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 18, 2013, 5:42 AM CDT (10:42 UTC)
- Expired
- Apr 18, 2013, 2:00 PM CDT
- In force
- 8 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 22 counties
Bond County, IL, Clinton County, IL, Fayette County, IL, Jersey County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Randolph County, IL, Saint Clair County, IL, Washington County, IL, City of Saint Louis, MO, Iron County, MO, Jefferson County, MO, Madison County, MO, Reynolds County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Washington County, MO
The radar
The St Louis radar (KLSX), 56 km from the middle of the area, began a volume at 10:42 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
- 50%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 10%
- 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
- 60%
Warnings issued inside it
3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 18, 6:01 AM CDT | Severe Thunderstorm Warning | LSX | Crawford, Washington | 44 min |
| Apr 18, 11:51 AM CDT | Flash Flood Warning | LSX | Bond, Clinton, Madison, Monroe, Saint Clair | 6 hr |
| Apr 18, 12:46 PM CDT | Severe Thunderstorm Warning | LSX | Clinton, Fayette, Marion, Washington | 44 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, 10.7 hours before the alert went out and 241 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 412 m above ground
- 0-6 km bulk shear
- 68 kt
- 0-1 km storm-relative helicity
- 356 m²/s²
- 0-3 km storm-relative helicity
- 444 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 11.4
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 17, 8:21 PM CDT | Mesoscale Discussion | SPC | Cass, Champaign, Christian, Coles, DeWitt, Douglas and 21 more | 84 min |
| Apr 17, 8:53 PM CDT | Mesoscale Discussion | SPC | Calhoun, Greene, Jersey, Pike, Scott | 97 min |
| Apr 17, 9:57 PM CDT | Tornado Watch | SPC | Adams, Brown, Pike | 7 hr |
| Apr 17, 10:48 PM CDT | Mesoscale Discussion | SPC | Champaign, Christian, Coles, DeWitt, Douglas, Edgar and 12 more | 57 min |
| Apr 17, 11:46 PM CDT | Mesoscale Discussion | SPC | Calhoun, Greene, Morgan, Pike, Scott | 89 min |
| Apr 18, 2:01 AM CDT | Mesoscale Discussion | SPC | Calhoun, Jersey | 89 min |
| Apr 18, 4:02 AM CDT | Mesoscale Discussion | SPC | Calhoun, Greene, Jersey, Monroe | 58 min |
| Apr 18, 5:36 AM CDT | Mesoscale Discussion | SPC | Bond, Clinton, Fayette, Madison, Monroe, Montgomery and 3 more | 54 min |
| Apr 18, 7:25 AM CDT | Mesoscale Discussion | SPC | Champaign, Clark, Clay, Coles, Crawford, Cumberland and 17 more | 95 min |
| Apr 18, 8:31 AM CDT | Tornado Watch | SPC | Clark, Clay, Coles, Crawford, Cumberland, Douglas and 6 more | 7 hr |
| Apr 18, 9:25 AM CDT | Tornado Watch | SPC | Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more | 8 hr |
| Apr 18, 11:14 AM CDT | Mesoscale Discussion | SPC | Clark, Clay, Crawford, Jasper, Lawrence, Marion and 4 more | 2 hr |
| Apr 18, 12:48 PM CDT | Mesoscale Discussion | SPC | Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more | 87 min |
| Apr 18, 2:47 PM CDT | Mesoscale Discussion | SPC | Clark, Crawford, Lawrence | 88 min |
| Apr 18, 7:26 AM CDT | Mesoscale Discussion | SPC | Bollinger, Butler, Cape Girardeau, Carter, Dunklin, Howell and 9 more | 2 hr |
Nearby
Tornado Watches in Illinois, 2013Tornado Watches in Missouri, 2013Every tornado watch in 2013
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.