Alert archive / Minnesota / Tornado Watches in 2009

Tornado Watch 678

August 8, 200930 counties in Minnesota; 18 counties in Wisconsin

The Storm Prediction Center issued this tornado watch at Aug 8, 2009, 3:46 PM CDT for 30 counties in Minnesota; 18 counties in Wisconsin. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued
Aug 8, 2009, 3:46 PM CDT (20:46 UTC)
Expired
Aug 9, 2009, 12:00 AM CDT
In force
8 hr
Issued by
the Storm Prediction Center
Largest hail expected
3 in
Strongest gust expected
60 kt
All 48 counties

Anoka County, MN, Benton County, MN, Blue Earth County, MN, Carver County, MN, Chisago County, MN, Dakota County, MN, Dodge County, MN, Faribault County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Hennepin County, MN, Isanti County, MN, Kanabec County, MN, Le Sueur County, MN, Mille Lacs County, MN, Morrison County, MN, Mower County, MN, Olmsted County, MN, Pine 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, Barron County, WI, Buffalo County, WI, Burnett County, WI, Chippewa County, WI, Clark County, WI, Dunn County, WI, Eau Claire County, WI, Jackson County, WI, Pepin County, WI, Pierce County, WI, Polk County, WI, Price County, WI, Rusk County, WI, Saint Croix County, WI, Sawyer County, WI, Taylor County, WI, Trempealeau County, WI, Washburn County, WI

The radar

The Minneapolis radar (KMPX), 76 km from the middle of the area, began a volume at 20:45 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
50%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
40%
Ten or more severe hail reports
70%
One or more hailstones of 2 inches or more
70%
Six or more combined severe hail and wind reports
95%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Aug 8, 8:31 PM CDTTornado WarningMPXHennepin29 min
Aug 8, 8:49 PM CDTTornado WarningMPXAnoka, Hennepin, Ramsey26 min
Aug 8, 9:13 PM CDTTornado WarningMPXAnoka, Ramsey, Washington32 min
Aug 8, 9:43 PM CDTTornado WarningMPXWashington32 min
Aug 8, 10:01 PM CDTTornado WarningMPXWashington29 min
Aug 8, 10:14 PM CDTTornado WarningMPXWashington31 min
Aug 8, 10:29 PM CDTTornado WarningMPXSaint Croix46 min
Aug 8, 11:14 PM CDTTornado WarningMPXDunn, Saint Croix46 min
Aug 9, 12:00 AM CDTTornado WarningMPXDunn30 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, 8.8 hours before the alert went out and 79 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 2009-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 368 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 2009-08-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 237 square meters per square second.19395878Sfc1 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
368 J/kg
Mixed-layer CIN
-296 J/kg
Mixed-layer LCL
896 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
237 m²/s²
0-3 km storm-relative helicity
260 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.2

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 7, 8:58 PM CDTMesoscale DiscussionSPCBlue Earth, Brown, Cottonwood, Dodge, Faribault, Fillmore and 15 more92 min
Aug 7, 10:14 PM CDTSevere Thunderstorm WatchSPCBlue Earth, Brown, Carver, Chippewa, Cottonwood, Dodge and 20 more6 hr
Aug 8, 1:29 AM CDTMesoscale DiscussionSPCBlue Earth, Brown, Carver, Chippewa, Cottonwood, Dakota and 31 more2 hr
Aug 8, 9:29 AM CDTMesoscale DiscussionSPCAnoka, Brown, Carver, Dakota, Goodhue, Hennepin and 12 more91 min
Aug 8, 12:16 PM CDTMesoscale DiscussionSPCAnoka, Blue Earth, Brown, Carver, Chippewa, Chisago and 36 more29 min
Aug 8, 12:47 PM CDTTornado WatchSPCBig Stone, Brown, Chippewa, Cottonwood, Douglas, Jackson and 23 more5 hr
Aug 8, 2:17 PM CDTMesoscale DiscussionSPCWilkin58 min
Aug 8, 3:27 PM CDTMesoscale DiscussionSPCAnoka, Benton, Blue Earth, Brown, Carver, Chippewa and 47 more33 min
Aug 8, 5:36 PM CDTMesoscale DiscussionSPCAnoka, Benton, Blue Earth, Brown, Carver, Chisago and 26 more84 min

Nearby

Tornado Watches in Minnesota, 2009Tornado Watches in Wisconsin, 2009Every tornado watch in 2009

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.