Alert archive / Wisconsin / Severe Thunderstorm Watches in 2017
Severe Thunderstorm Watch 217
The Storm Prediction Center issued this severe thunderstorm watch at May 15, 2017, 7:52 PM CDT for 8 counties in Illinois; 9 counties in Wisconsin. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- May 15, 2017, 7:52 PM CDT (00:52 UTC)
- Expired
- May 15, 2017, 11:20 PM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
Counties Boone County, IL, DeKalb County, IL, Jo Daviess County, IL, Kane County, IL, McHenry County, IL, Ogle County, IL, Stephenson County, IL, Winnebago County, IL, Dane County, WI, Green County, WI, Iowa County, WI, Jefferson County, WI, Kenosha County, WI, Lafayette County, WI, Racine County, WI, Rock County, WI, Walworth County, WI
The radar
The Milwaukee radar (KMKX), 86 km from the middle of the area, began a volume at 00:56 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
- 2%
- Ten or more severe wind reports
- 30%
- 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
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
10 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 15, 7:52 PM CDT | Severe Thunderstorm Warning | DVN | Jo Daviess | 38 min |
| May 15, 7:57 PM CDT | Severe Thunderstorm Warning | MKX | Iowa, Lafayette | 63 min |
| May 15, 8:29 PM CDT | Severe Thunderstorm Warning | DVN | Carroll, Jo Daviess, Stephenson | 76 min |
| May 15, 8:44 PM CDT | Severe Thunderstorm Warning | MKX | Dane, Green, Iowa, Lafayette | 61 min |
| May 15, 8:47 PM CDT | Severe Thunderstorm Warning | MKX | Green, Lafayette | 58 min |
| May 15, 9:26 PM CDT | Severe Thunderstorm Warning | MKX | Columbia, Dane, Sauk | 49 min |
| May 15, 9:27 PM CDT | Severe Thunderstorm Warning | MKX | Rock | 48 min |
| May 15, 9:40 PM CDT | Severe Thunderstorm Warning | LOT | Winnebago | 35 min |
| May 15, 10:07 PM CDT | Severe Thunderstorm Warning | MKX | Jefferson, Walworth, Waukesha | 38 min |
| May 15, 10:24 PM CDT | Severe Thunderstorm Warning | MKX | Kenosha, Milwaukee, Racine, Waukesha | 51 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, 0.9 hours before the alert went out and 136 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
- 865 J/kg
- Mixed-layer CIN
- -169 J/kg
- Mixed-layer LCL
- 1965 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 71 m²/s²
- 0-3 km storm-relative helicity
- 148 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.2
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 15, 7:19 PM CDT | Mesoscale Discussion | SPC | Boone, Carroll, DeKalb, Jo Daviess, Kane, Lee and 5 more | 56 min |
| May 15, 10:14 PM CDT | Mesoscale Discussion | SPC | Boone, DeKalb, DuPage, Kane, Kendall, Lake and 2 more | 61 min |
| May 15, 9:48 PM CDT | Severe Thunderstorm Watch | SPC | Buffalo, Crawford, Jackson, La Crosse, Monroe, Pepin and 4 more | 5 hr |
| May 16, 2:13 AM CDT | Mesoscale Discussion | SPC | Buffalo, La Crosse, Trempealeau | 92 min |
| May 16, 12:57 PM CDT | Mesoscale Discussion | SPC | Buffalo, Clark, Eau Claire, Jackson, Marathon, Menominee and 7 more | 2 hr |
| May 16, 3:32 PM CDT | Mesoscale Discussion | SPC | Adams, Barron, Buffalo, Burnett, Calumet, Chippewa and 33 more | 88 min |
| May 16, 4:02 PM CDT | Tornado Watch | SPC | Ashland, Barron, Bayfield, Buffalo, Burnett, Chippewa and 24 more | 6 hr |
| May 16, 6:25 PM CDT | Mesoscale Discussion | SPC | Ashland, Barron, Bayfield, Brown, Buffalo, Burnett and 32 more | 65 min |
Nearby
Severe Thunderstorm Watches in Wisconsin, 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.