Alert archive / Iowa / Severe Thunderstorm Watches in 2007
Severe Thunderstorm Watch 541
The Storm Prediction Center issued this severe thunderstorm watch at Jul 18, 2007, 11:07 PM CDT for 10 counties in Illinois; 14 counties in Iowa. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 18, 2007, 11:07 PM CDT (04:07 UTC)
- Expired
- Jul 19, 2007, 2:58 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 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, 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, Hancock County, IL, Henderson County, IL, Henry County, IL, McDonough 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), 53 km from the middle of the area, began a volume at 04:08 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
- 2%
- Ten or more severe wind reports
- 40%
- 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
- 80%
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, 4.1 hours before the alert went out and 60 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
- 3404 J/kg
- Mixed-layer CIN
- -4 J/kg
- Mixed-layer LCL
- 988 m above ground
- 0-6 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 69 m²/s²
- 0-3 km storm-relative helicity
- 135 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 7.1
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 18, 7:29 PM CDT | Severe Thunderstorm Watch | SPC | Cook, DuPage, Ford, Grundy, Iroquois, Kane and 5 more | 7 hr |
| Jul 18, 9:06 PM CDT | Mesoscale Discussion | SPC | Bureau, Carroll, Champaign, Coles, Cook, DeKalb and 38 more | 84 min |
| Jul 18, 10:23 PM CDT | Mesoscale Discussion | SPC | Mercer, Rock Island | 97 min |
| Jul 19, 1:27 PM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Clark, Clay, Clinton, Coles and 26 more | 93 min |
| Jul 19, 1:42 PM CDT | Severe Thunderstorm Watch | SPC | Bond, Calhoun, Clay, Clinton, Crawford, Edwards and 30 more | 6 hr |
| Jul 19, 5:38 PM CDT | Mesoscale Discussion | SPC | Clinton, Edwards, Franklin, Gallatin, Hamilton, Hardin and 17 more | 97 min |
| Jul 18, 8:39 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Ida, Monona, Plymouth, Woodbury | 7 hr |
| Jul 18, 10:39 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Audubon, Black Hawk, Boone, Calhoun, Carroll and 23 more | 5 hr |
| Jul 19, 1:41 AM CDT | Mesoscale Discussion | SPC | Adair, Audubon, Black Hawk, Boone, Calhoun, Carroll and 23 more | 94 min |
Nearby
Severe Thunderstorm Watches in Iowa, 2007Severe Thunderstorm Watches in Illinois, 2007Every severe thunderstorm watch in 2007
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.