Alert archive / Illinois / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 68

March 6, 201731 counties in Illinois; 13 counties in Wisconsin

The Storm Prediction Center issued this severe thunderstorm watch at Mar 6, 2017, 10:35 PM CST for 31 counties in Illinois; 13 counties in Wisconsin. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Mar 6, 2017, 10:35 PM CST (04:35 UTC)
Expired: Mar 7, 2017, 3:03 AM CST
In force: 4 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 60 kt

All 44 counties

Boone County, IL, Champaign County, IL, Christian County, IL, Coles County, IL, Cook County, IL, DeKalb County, IL, DeWitt County, IL, Douglas County, IL, DuPage County, IL, Edgar County, IL, Ford County, IL, Grundy County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, McHenry County, IL, McLean County, IL, Moultrie County, IL, Ogle County, IL, Piatt County, IL, Shelby County, IL, Vermilion County, IL, Will County, IL, Winnebago County, IL, Dodge County, WI, Fond du Lac County, WI, Green Lake County, WI, Jefferson County, WI, Kenosha County, WI, Milwaukee County, WI, Ozaukee County, WI, Racine County, WI, Rock County, WI, Sheboygan County, WI, Walworth County, WI, Washington County, WI, Waukesha County, WI

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: 40%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 10%
One or more hailstones of 2 inches or more: 10%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

20 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Mar 6, 10:59 PM CST	Severe Thunderstorm Warning	LOT	Lee, Ogle, Winnebago	61 min
Mar 6, 11:08 PM CST	Severe Thunderstorm Warning	MKX	Columbia, Green Lake, Marquette, Sauk	28 min
Mar 6, 11:13 PM CST	Severe Thunderstorm Warning	MKX	Dane, Green, Lafayette, Rock	47 min
Mar 6, 11:30 PM CST	Severe Thunderstorm Warning	MKX	Rock	30 min
Mar 6, 11:48 PM CST	Severe Thunderstorm Warning	MKX	Jefferson, Rock, Walworth	27 min
Mar 6, 11:49 PM CST	Severe Thunderstorm Warning	ILX	Cass, Fulton, Logan, Mason, Menard, Peoria and 2 more	56 min
Mar 7, 12:03 AM CST	Tornado Warning	ILX	McLean, Tazewell	27 min
Mar 7, 12:05 AM CST	Severe Thunderstorm Warning	ILX	Logan, Menard, Morgan, Sangamon	25 min
Mar 7, 12:06 AM CST	Severe Thunderstorm Warning	LOT	DeKalb, LaSalle, Lee, Livingston	54 min
Mar 7, 12:21 AM CST	Severe Thunderstorm Warning	ILX	DeWitt, Logan, McLean, Marshall, Woodford	54 min
Mar 7, 12:28 AM CST	Severe Thunderstorm Warning	MKX	Kenosha, Milwaukee, Racine, Walworth, Waukesha	47 min
Mar 7, 12:30 AM CST	Severe Thunderstorm Warning	ILX	Christian, DeWitt, Logan, Macon, Morgan, Sangamon	60 min
Mar 7, 12:30 AM CST	Severe Thunderstorm Warning	MKX	Fond du Lac, Ozaukee, Sheboygan, Washington	45 min
Mar 7, 12:43 AM CST	Severe Thunderstorm Warning	LOT	Cook, DuPage, Grundy, Kane, Kankakee, Kendall and 2 more	62 min
Mar 7, 1:08 AM CST	Severe Thunderstorm Warning	LOT	Ford, Iroquois, Kankakee, Livingston	52 min
Mar 7, 1:16 AM CST	Severe Thunderstorm Warning	ILX	Christian, Macon, Moultrie, Piatt, Shelby	44 min
Mar 7, 1:46 AM CST	Severe Thunderstorm Warning	ILX	Champaign, Vermilion	29 min
Mar 7, 1:57 AM CST	Severe Thunderstorm Warning	ILX	Coles, Cumberland, Douglas, Shelby	48 min
Mar 7, 2:17 AM CST	Severe Thunderstorm Warning	ILX	Champaign, Vermilion	28 min
Mar 7, 2:25 AM CST	Severe Thunderstorm Warning	ILX	Clark, Coles, Edgar	35 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, 4.6 hours before the alert went out and 158 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 39 J/kg
Mixed-layer CIN: -343 J/kg
Mixed-layer LCL: 1016 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 407 m²/s²
0-3 km storm-relative helicity: 489 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 6, 7:42 PM CST	Mesoscale Discussion	SPC	Bureau, Carroll, Henderson, Henry, Jo Daviess, Knox and 12 more	63 min
Mar 6, 8:10 PM CST	Mesoscale Discussion	SPC	Alexander	3 hr
Mar 6, 8:22 PM CST	Mesoscale Discussion	SPC	Adams, Bond, Brown, Calhoun, Cass, Christian and 24 more	2 hr
Mar 6, 8:52 PM CST	Tornado Watch	SPC	Adams, Bond, Brown, Bureau, Calhoun, Carroll and 38 more	6 hr
Mar 6, 10:15 PM CST	Mesoscale Discussion	SPC	Boone, DeKalb, DeWitt, Ford, Grundy, Kane and 11 more	60 min
Mar 6, 11:13 PM CST	Mesoscale Discussion	SPC	Alexander, Bond, Calhoun, Clay, Clinton, Cumberland and 31 more	2 hr
Mar 7, 1:53 AM CST	Mesoscale Discussion	SPC	Champaign, Coles, Cumberland, Douglas, Edgar, Iroquois and 3 more	97 min
Mar 7, 2:58 AM CST	Mesoscale Discussion	SPC	Alexander, Franklin, Gallatin, Hamilton, Hardin, Jackson and 8 more	92 min
Mar 6, 6:11 PM CST	Mesoscale Discussion	SPC	Buffalo, Burnett, Dunn, Pepin, Pierce, Polk and 1 more	2 hr
Mar 6, 7:00 PM CST	Mesoscale Discussion	SPC	Adams, Barron, Burnett, Chippewa, Clark, Eau Claire and 11 more	2 hr
Mar 6, 7:42 PM CST	Severe Thunderstorm Watch	SPC	Adams, Columbia, Crawford, Dane, Grant, Green and 11 more	5 hr

Nearby

Severe Thunderstorm Watches in Illinois, 2017 Severe Thunderstorm Watches in Wisconsin, 2017 Every 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.