Alert archive / Iowa / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 172
The Storm Prediction Center issued this severe thunderstorm watch at Apr 14, 2012, 8:41 PM CDT for 9 counties in Illinois; 15 counties in Iowa. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 14, 2012, 8:41 PM CDT (01:41 UTC)
- Expired
- Apr 15, 2012, 1:00 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 24 counties
Cedar County, IA, Clinton County, IA, Des Moines County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Washington County, IA, Bureau County, IL, Carroll County, IL, Henderson County, IL, Henry County, IL, Mercer County, IL, Putnam County, IL, Rock Island County, IL, Warren County, IL, Whiteside County, IL
The radar
The Quad Cities radar (KDVN), 66 km from the middle of the area, began a volume at 01:43 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
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 14, 9:03 PM CDT | Severe Thunderstorm Warning | DVN | Mercer, Rock Island | 43 min |
| Apr 14, 9:14 PM CDT | Severe Thunderstorm Warning | DVN | Benton, Iowa, Johnson, Keokuk, Linn, Washington | 61 min |
| Apr 14, 9:26 PM CDT | Severe Thunderstorm Warning | DVN | Henry, Jefferson, Keokuk, Washington | 64 min |
| Apr 14, 9:38 PM CDT | Severe Thunderstorm Warning | DVN | Benton, Cedar, Iowa, Johnson, Jones, Keokuk and 4 more | 55 min |
| Apr 14, 9:55 PM CDT | Severe Thunderstorm Warning | DVN | Des Moines, Henry, Jefferson, Keokuk, Louisa, Washington | 65 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
Davenport, (KDVN), launched 00:00Z, 1.7 hours before the alert went out and 72 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
- 300 J/kg
- Mixed-layer CIN
- -50 J/kg
- Mixed-layer LCL
- 726 m above ground
- 0-6 km bulk shear
- 69 kt
- 0-1 km storm-relative helicity
- 124 m²/s²
- 0-3 km storm-relative helicity
- 126 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 14, 9:54 PM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Carroll, DeKalb, DuPage, Henry and 12 more | 96 min |
| Apr 15, 4:22 PM CDT | Mesoscale Discussion | SPC | Bond, Brown, Calhoun, Cass, Christian, Clinton and 31 more | 83 min |
| Apr 15, 4:42 PM CDT | Tornado Watch | SPC | Adams, Bond, Brown, Calhoun, Cass, Clinton and 15 more | 6 hr |
| Apr 15, 6:12 PM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 25 more | 63 min |
| Apr 14, 7:50 PM CDT | Mesoscale Discussion | SPC | Benton, Buchanan, Cedar, Delaware, Henry, Iowa and 13 more | 55 min |
| Apr 14, 7:51 PM CDT | Mesoscale Discussion | SPC | Cherokee, Ida, Lyon, Monona, O'Brien, Osceola and 3 more | 84 min |
| Apr 14, 10:09 PM CDT | Severe Thunderstorm Watch | SPC | Fremont, Harrison, Mills, Monona, Montgomery, Page and 3 more | 6 hr |
| Apr 14, 11:28 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Appanoose, Audubon, Boone, Carroll and 28 more | 92 min |
| Apr 15, 3:25 AM CDT | Mesoscale Discussion | SPC | Adams, Audubon, Cass, Fremont, Harrison, Mills and 5 more | 95 min |
| Apr 15, 1:56 PM CDT | Mesoscale Discussion | SPC | Audubon, Boone, Buena Vista, Butler, Calhoun, Carroll and 28 more | 94 min |
| Apr 15, 3:37 PM CDT | Tornado Watch | SPC | Cerro Gordo, Chickasaw, Clay, Dickinson, Emmet, Floyd and 8 more | 7 hr |
Nearby
Severe Thunderstorm Watches in Iowa, 2012Severe Thunderstorm Watches in Illinois, 2012Every severe thunderstorm watch in 2012
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.