Alert archive / Missouri / Severe Thunderstorm Watches in 2017
Severe Thunderstorm Watch 434
The Storm Prediction Center issued this severe thunderstorm watch at Jul 23, 2017, 12:38 AM CDT for 19 counties in Illinois; 22 counties in Missouri. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 23, 2017, 12:38 AM CDT (05:38 UTC)
- Expired
- Jul 23, 2017, 5:19 AM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 65 kt
All 41 counties
Adams County, IL, Bond County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Clinton County, IL, Fayette County, IL, Greene County, IL, Jersey County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Pike County, IL, Saint Clair County, IL, Scott County, IL, Washington County, IL, Audrain County, MO, Boone County, MO, Callaway County, MO, City of Saint Louis, MO, Cole County, MO, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Marion County, MO, Moniteau County, MO, Monroe County, MO, Montgomery County, MO, Osage County, MO, Pike County, MO, Ralls County, MO, Saint Charles County, MO, Saint Louis County, MO, Shelby County, MO, Warren County, MO
The radar
The St Louis radar (KLSX), 99 km from the middle of the area, began a volume at 05:38 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
- 5%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
15 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 23, 12:54 AM CDT | Severe Thunderstorm Warning | LSX | Callaway | 51 min |
| Jul 23, 1:08 AM CDT | Severe Thunderstorm Warning | LSX | Audrain, Boone, Callaway, Monroe, Shelby | 52 min |
| Jul 23, 1:37 AM CDT | Severe Thunderstorm Warning | LSX | Callaway, Gasconade, Montgomery, Warren | 38 min |
| Jul 23, 1:46 AM CDT | Severe Thunderstorm Warning | LSX | Franklin, Saint Charles, Warren | 44 min |
| Jul 23, 1:49 AM CDT | Severe Thunderstorm Warning | LSX | Audrain, Callaway, Monroe, Montgomery, Pike, Ralls | 41 min |
| Jul 23, 2:17 AM CDT | Severe Thunderstorm Warning | LSX | Pike | 43 min |
| Jul 23, 2:38 AM CDT | Severe Thunderstorm Warning | LSX | Saint Louis, City of Saint Louis | 52 min |
| Jul 23, 2:48 AM CDT | Severe Thunderstorm Warning | LSX | Calhoun, Greene, Jersey, Madison, Pike | 42 min |
| Jul 23, 3:08 AM CDT | Severe Thunderstorm Warning | ILX | Morgan, Scott | 52 min |
| Jul 23, 3:14 AM CDT | Severe Thunderstorm Warning | LSX | Madison | 46 min |
| Jul 23, 3:19 AM CDT | Severe Thunderstorm Warning | LSX | Saint Clair | 41 min |
| Jul 23, 3:25 AM CDT | Severe Thunderstorm Warning | LSX | Greene, Jersey, Macoupin, Montgomery | 50 min |
| Jul 23, 3:48 AM CDT | Severe Thunderstorm Warning | LSX | Bond, Clinton, Madison, Saint Clair, Washington | 42 min |
| Jul 23, 4:08 AM CDT | Severe Thunderstorm Warning | LSX | Fayette, Macoupin, Montgomery | 67 min |
| Jul 23, 4:24 AM CDT | Severe Thunderstorm Warning | LSX | Bond, Clinton, Fayette, Marion, Washington | 52 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, 5.6 hours before the alert went out and 267 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
- 2392 J/kg
- Mixed-layer CIN
- -34 J/kg
- Mixed-layer LCL
- 1185 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 51 m²/s²
- 0-3 km storm-relative helicity
- 233 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 6.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 22, 7:11 PM CDT | Mesoscale Discussion | SPC | Christian, Clark, Coles, Crawford, Cumberland, Douglas and 10 more | 94 min |
| Jul 22, 11:48 PM CDT | Mesoscale Discussion | SPC | Calhoun, Pike | 87 min |
| Jul 23, 3:12 AM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Christian, Clay, Clinton, Edwards and 23 more | 2 hr |
| Jul 23, 3:32 AM CDT | Severe Thunderstorm Watch | SPC | Christian, Clark, Clay, Coles, Crawford, Cumberland and 14 more | 4 hr |
| Jul 23, 5:23 AM CDT | Mesoscale Discussion | SPC | Clay, Crawford, Edwards, Effingham, Hamilton, Jasper and 5 more | 2 hr |
| Jul 23, 1:03 PM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Champaign, Cook, DeKalb, Douglas and 23 more | 2 hr |
| Jul 22, 9:22 PM CDT | Mesoscale Discussion | SPC | Adair, Andrew, Bates, Boone, Buchanan, Caldwell and 27 more | 113 min |
Nearby
Severe Thunderstorm Watches in Missouri, 2017Severe Thunderstorm Watches in Illinois, 2017Every severe thunderstorm watch in 2017
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.