Alert archive / Minnesota / Severe Thunderstorm Watches in 2007

Severe Thunderstorm Watch 533

July 18, 200720 counties in Minnesota; 16 counties in Wisconsin

The Storm Prediction Center issued this severe thunderstorm watch at Jul 18, 2007, 3:59 PM CDT for 20 counties in Minnesota; 16 counties in Wisconsin. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Jul 18, 2007, 3:59 PM CDT (20:59 UTC)
Expired
Jul 18, 2007, 8:45 PM CDT
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 36 counties

Anoka County, MN, Carver County, MN, Dakota County, MN, Dodge County, MN, Fillmore County, MN, Goodhue County, MN, Hennepin County, MN, Houston County, MN, Le Sueur County, MN, Olmsted County, MN, Ramsey County, MN, Rice County, MN, Scott County, MN, Sherburne County, MN, Steele County, MN, Wabasha County, MN, Waseca County, MN, Washington County, MN, Winona County, MN, Wright County, MN, Adams County, WI, Buffalo County, WI, Chippewa County, WI, Clark County, WI, Dunn County, WI, Eau Claire County, WI, Jackson County, WI, Juneau County, WI, La Crosse County, WI, Monroe County, WI, Pepin County, WI, Pierce County, WI, Saint Croix County, WI, Taylor County, WI, Trempealeau County, WI, Vernon County, WI

The radar

The La Crosse radar (KARX), 108 km from the middle of the area, began a volume at 20:59 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
40%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
40%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 18, 4:53 PM CDTSevere Thunderstorm WarningMPXHennepin37 min
Jul 18, 7:08 PM CDTSevere Thunderstorm WarningMPXEau Claire37 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

Minneapolis, MN (KMPX), launched 12:00Z, 9.0 hours before the alert went out and 145 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-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 2007-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1891 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 12:00Z on 2007-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -61 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
1891 J/kg
Mixed-layer CIN
-18 J/kg
Mixed-layer LCL
641 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
-61 m²/s²
0-3 km storm-relative helicity
36 m²/s²
Significant tornado parameter
-0.2
Supercell composite
-1.6

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 17, 9:31 PM CDTSevere Thunderstorm WatchSPCDodge, Fillmore, Houston, Mower, Olmsted, Wabasha and 1 more6 hr
Jul 17, 11:24 PM CDTMesoscale DiscussionSPCFaribault, Freeborn, Jackson, Martin, Mower, Nobles and 1 more96 min
Jul 18, 3:35 AM CDTMesoscale DiscussionSPCDodge, Fillmore, Houston, Mower, Olmsted, Steele and 1 more85 min
Jul 18, 12:17 PM CDTMesoscale DiscussionSPCAnoka, Chisago, Isanti, Ramsey, Washington118 min
Jul 18, 12:47 PM CDTMesoscale DiscussionSPCBlue Earth, Cottonwood, Faribault, Fillmore, Freeborn, Houston and 10 more2 hr
Jul 18, 2:09 PM CDTSevere Thunderstorm WatchSPCFaribault, Freeborn, Jackson, Martin, Mower, Nobles and 1 more4 hr
Jul 18, 3:42 PM CDTMesoscale DiscussionSPCAnoka, Dakota, Goodhue, Hennepin, Olmsted, Ramsey and 4 more63 min
Jul 18, 4:59 PM CDTMesoscale DiscussionSPCFillmore, Houston91 min
Jul 18, 6:44 PM CDTMesoscale DiscussionSPCHouston, Winona2 hr
Jul 18, 1:37 PM CDTSevere Thunderstorm WatchSPCBrown, Calumet, Dodge, Door, Fond du Lac, Green Lake and 18 more7 hr
Jul 18, 5:35 PM CDTSevere Thunderstorm WatchSPCGrant, Green, Lafayette, Rock6 hr
Jul 18, 5:46 PM CDTMesoscale DiscussionSPCBrown, Calumet, Dodge, Fond du Lac, Green Lake, Manitowoc and 11 more119 min
Jul 18, 6:38 PM CDTMesoscale DiscussionSPCKenosha97 min
Jul 18, 6:50 PM CDTMesoscale DiscussionSPCGrant, Green, Lafayette85 min

Nearby

Severe Thunderstorm Watches in Minnesota, 2007Severe Thunderstorm Watches in Wisconsin, 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.