Tornadoes · United States · Minnesota · 2006

F0 tornado, Brown County, Minnesota, August 24, 2006

Name: F0 tornado, Brown County, Minnesota, August 24, 2006
Start: 2006-08-24T22:08:00.000Z
Location: Brown County, Minnesota

This F0 tornado ran 0.5 miles across Brown County on August 24, 2006, touching down at 5:08 PM CDT and reaching 30 yards wide. It killed nobody and injured 2, and did $200,000 of property damage.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

F040 to 72 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
F173 to 112 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
F2113 to 157 mph
Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
F3158 to 206 mph
Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.
F4207 to 260 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
F5261 to 318 mph
Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.
Unrated
The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

The record

Rating: F0
Date: August 24, 2006
Touchdown: 5:08 PM CDT (22:08 UTC)
Path length: 0.5 miles (0.8 km)
Path width: 30 yards (27 m)
Deaths: 0
Injuries: 2
Property damage: $200,000
County: Brown County
Touchdown point: 44.270, -94.430
Lift-off point: 44.280, -94.420
Record number: 828

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

The county was under a tornado watch, issued at 20:17 UTC and running to 05:00 UTC.

Issued (UTC)	Expired	Product	Office
13:54 UTC	20:17 UTC	Severe Thunderstorm Watch	MPX
20:17 UTC	05:00 UTC	Tornado Watch	MPX
22:14 UTC	22:30 UTC	Tornado Warning	MPX

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a Moderate Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:58 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

What forecasters said that day

The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Twin Cities, MN wrote its last area forecast discussion before the tornado touched down at Aug 24, 3:48 PM CDT, 1 hour 20 minutes earlier.

Area forecast discussion, Aug 24, 3:48 PM CDT, 1 hour 20 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
348 PM CDT THU AUG 24 2006

.DISCUSSION...TONIGHT THROUGH SUNDAY
DEEP SURFACE IN CENTRAL SOUTH DAKOTA ATTM WITH PRESSURE NEAR 1000
MB. VERY MOIST...UNSTABLE AIR PUSHING INTO THE MPX CWA IN ADVANCE
OF THIS SYSTEM WITH THE LATEST SPC HRLY MESOSCALE ANALYSIS FOR
20Z SHOWING A REMARKABLE 0.40 0-3 KM VGP TO THE SOUTH AND WEST OF
THE MINNESOTA RIVER VALLEY WITH 0.50 NOSING INTO SOUTH-CENTRAL MN.
THE 0-1 KM BULK SHEAR HAS BEEN PICKING UP TO AROUND 15 TO 25 KNOTS
TOO WHILE THE 0-6 KM BULK SHEAR IS ABOVE 50 KNOTS OVER MUCH OF
THE CWA. REMARKABLY STRONG NSE FOR AUGUST

WEVE BEEN WORKING WITH EXTREMELY LARGE HAIL PRODUCERS ALL DAY
WITH INITIAL ACTIVITY QUITE ELEVATED. HOWEVER...LOWERING LCL AND
LFC FIGURES SUGGEST STORMS WILL BECOME MORE SURFACE ROOTED WITH
INCREASING TORNADO POTENTIAL.

PWAT VALUES PICK UP TO FROM 1.5 TO 2 INCHES AS THE LOW MOVES
EASTWARD ACROSS FAR SOUTHERN MN. WHILE MOISTURE TRANSPORT COULD BE
A GOOD DEAL BETTER FOR A FLOOD EVENT...WE DID ISSUE A FLASH FLOOD WATCH
FOR OUR EASTERN MN COUNTIES AND OUR WEST WISCONSIN COUNTIES.
SYSTEM MAKES ITS WAY EAST OF THE AREA ON FRIDAY AND WE DRY OUT.

LONGER TERM...SUNDAY NIGHT THROUGH THURSDAY
DISCUSSION NOT AVAILABLE THIS ISSUANCE.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH FRIDAY
     MORNING FOR ANOKA-BENTON-CARVER-CHISAGO-DAKOTA-GOODHUE-
     HENNEPIN-ISANTI-KANABEC-MILLE LACS-MORRISON-RAMSEY-RICE-
     SCOTT-SHERBURNE-STEARNS-TODD-WASHINGTON-WRIGHT COUNTY(IES).

WI...FLASH FLOOD WATCH FROM 7 PM CDT THIS EVENING THROUGH FRIDAY
     MORNING FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-
     POLK-RUSK-ST. CROIX COUNTY(IES).

&&

Hazardous weather outlook, Aug 24, 5:34 AM CDT, 11 hours 34 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
534 AM CDT THU AUG 24 2006

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
251045-
DOUGLAS-TODD-MORRISON-MILLE LACS-KANABEC-STEVENS-POPE-STEARNS-
BENTON-SHERBURNE-ISANTI-CHISAGO-LAC QUI PARLE-SWIFT-CHIPPEWA-
KANDIYOHI-MEEKER-WRIGHT-HENNEPIN-ANOKA-RAMSEY-WASHINGTON-
YELLOW MEDICINE-RENVILLE-MCLEOD-SIBLEY-CARVER-SCOTT-DAKOTA-
REDWOOD-BROWN-NICOLLET-LE SUEUR-RICE-GOODHUE-WATONWAN-BLUE EARTH-
WASECA-STEELE-MARTIN-FARIBAULT-FREEBORN-POLK-BARRON-RUSK-
ST. CROIX-PIERCE-DUNN-PEPIN-EAU CLAIRE-
534 AM CDT THU AUG 24 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND
SOUTH CENTRAL MINNESOTA...AND WEST CENTRAL WISCONSIN.

.DAY ONE...TODAY AND TONIGHT

THERE IS MODERATE RISK OF SEVERE WEATHER ACROSS WEST CENTRAL AND
SOUTHERN MINNESOTA AND FAR WEST CENTRAL WISCONSIN. THERE IS A
SLIGHT RISK OF SEVERE WEATHER ACROSS THE REST OF THE OUTLOOK AREA.

SEVERAL WEATHER FEATURES WILL BRING POTENTIAL FOR SIGNIFICANT
SEVERE WEATHER DEVELOPMENT TODAY AND TONIGHT. THE FIRST FOCUS FOR
THUNDERSTORMS WILL BE A NEARLY STATIONARY WARM FRONTAL BOUNDARY
POSITIONED ACROSS FAR SOUTHERN MINNESOTA AND WEST CENTRAL
WISCONSIN THROUGH THE AFTERNOON. THE ATMOSPHERE TO THE NORTH OF
THIS BOUNDARY WILL BECOME UNSTABLE AS TEMPERATURES WARM UP AND
MOISTURE INCREASES. THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG
AND NORTH OF THIS BOUNDARY. STRONG VERTICAL WIND SHEAR AND
MODERATE INSTABILITY WILL ALLOW THESE STORMS TO POTENTIALLY BECOME
SEVERE...WITH LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES
POSSIBLE. THE GREATEST RISK FOR TORNADOES WILL BE ALONG AND JUST
NORTH OF THE FRONT...OR SOUTHWEST OF AN ALEXANDRIA TO ST. CLOUD
MINNESOTA TO NEW RICHMOND TO MENOMONIE WISCONSIN LINE. THE FRONT
WILL BEGIN TO MOVE NORTH AND EAST TOWARDS SOUTH CENTRAL MINNESOTA
AND FAR WEST CENTRAL WISCONSIN THIS EVENING. STORMS THAT DEVELOP
ALONG THIS FRONT WILL LIKELY EXPAND INTO A LARGE THUNDERSTORM
COMPLEX LATE THIS EVENING BRINGING HEAVY RAIN WITH IT.

A SECOND AREA OF THUNDERSTORMS WILL BE ASSOCIATED WITH A SURFACE
LOW PRESSURE SYSTEM AND COLD FRONT MOVING EAST OUT OF SOUTH
DAKOTA. THUNDERSTORM ACTIVITY WILL LIKELY BE CONFINED TO THE
IMMEDIATE LOCATION OF THE COLD FRONT WHICH WILL ENTER SOUTHWEST
MINNESOTA THIS EVENING. SOME ISOLATED THUNDERSTORMS MAY DEVELOP
WELL AHEAD OF THE FRONT ACROSS EXTREME SOUTHERN MINNESOTA AND
SOUTH OF THE NEARLY STATIONARY WARM FRONT. ALL OF THESE
THUNDERSTORMS WILL HAVE THE POTENTIAL TO BECOME SEVERE WITH LARGE
HAIL AND DAMAGING WINDS...ALONG WITH ISOLATED TORNADOES. THIS
ACTIVITY WILL MOVE EASTWARD LATE TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

SHOWERS AND THUNDERSTORMS MAY LINGER INTO THE EARLY AFTERNOON HOURS
FRIDAY IN WEST CENTRAL WISCONSIN...BUT THEY ARE EXPECTED TO REMAIN
BELOW SEVERE LEVELS AT THIS TIME. NO HAZARDOUS WEATHER IS EXPECTED
THROUGH WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION WILL LIKELY BE NEEDED THIS AFTERNOON
AND TONIGHT.

MDB

In the hours before

Local storm report, Aug 24, 4:34 PM CDT, 34 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
434 PM CDT THU AUG 24 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0420 PM     HAIL             4 S ELMWOOD             44.72N 92.15W
08/24/2006  E1.75 INCH       PIERCE             WI   TRAINED SPOTTER

            HAIL LASTED 5 MINUTES.

&&

AZ

Local storm report, Aug 24, 4:37 PM CDT, 31 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
437 PM CDT THU AUG 24 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0437 PM     HAIL             NEW MUNICH              45.63N 94.75W
08/24/2006  E0.75 INCH       STEARNS            MN   FIRE DEPT/RESCUE

&&

AZ

Local storm report, Aug 24, 4:49 PM CDT, 19 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
449 PM CDT THU AUG 24 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0444 PM     HAIL             10 S MENOMONIE          44.74N 91.91W
08/24/2006  E0.75 INCH       DUNN               WI   TRAINED SPOTTER

&&

BVS

Local storm report, Aug 24, 4:53 PM CDT, 15 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
453 PM CDT THU AUG 24 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0450 PM     HAIL             12 SSE MENOMONIE        44.73N 91.82W
08/24/2006  E1.00 INCH       DUNN               WI   TRAINED SPOTTER

            1 1/8 INCH HAIL.

&&

BVS

Local storm report, Aug 24, 4:58 PM CDT, 10 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
458 PM CDT THU AUG 24 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0456 PM     HAIL             AVON                    45.61N 94.45W
08/24/2006  E0.75 INCH       STEARNS            MN   FIRE DEPT/RESCUE

&&

AZ

Local storm report, Aug 24, 4:59 PM CDT, 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
459 PM CDT THU AUG 24 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0456 PM     HAIL             RICHMOND                45.45N 94.52W
08/24/2006  E0.75 INCH       STEARNS            MN   FIRE DEPT/RESCUE

&&

AZ

The air that afternoon

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Minneapolis, MN (KMPX), 12:00Z

10.1 hours before the tornado, 91 km from the path. August 24, 2006.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.

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. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.

Mixed-layer CAPE: 1700 J/kg
Mixed-layer CIN: -236 J/kg
Surface CAPE: 5 J/kg
Mixed-layer LCL: 554 m above ground
0-6 km bulk shear: 47 kt
0-1 km bulk shear: 10 kt
0-1 km storm-relative helicity: 90 m²/s²
0-3 km storm-relative helicity: 115 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 6.5
0-3 km lapse rate: 2.9 K/km

Open this sounding in Storm Lab

The surface observations

New Ulm Municipal (ULM), 8 km from the path, in the two hours either side.

Time (UTC)	Temp (°F)	Dew point (°F)	Wind	Gust (kt)	Pressure (mb)
20:15 UTC	78.8	71.6	70° 8 kt		1004.1
20:20 UTC	78.8	71.6	70° 8 kt		1004.1
20:35 UTC	78.8	73.4	80° 9 kt		1003.7
20:40 UTC	78.8	73.4	80° 9 kt		1003.7
20:57 UTC	80.6	73.4	90° 8 kt		1003.4
21:00 UTC	80.6	73.4	90° 8 kt		1003.4
21:15 UTC	80.6	75.2	90° 7 kt		1003
21:20 UTC	80.6	75.2	90° 7 kt		1003
21:35 UTC	80.6	75.2	70° 6 kt		1003
21:40 UTC	80.6	75.2	70° 6 kt		1003
21:55 UTC	80.6	75.2	340° 10 kt		1002.7
22:00 UTC	80.6	75.2	340° 10 kt		1002.7
22:15 UTC	82.4	75.2	40° 8 kt		1002
22:20 UTC	82.4	75.2	40° 8 kt		1002
22:35 UTC	78.8	73.4	20° 7 kt		1001.7
22:40 UTC	78.8	73.4	20° 7 kt		1001.7
22:55 UTC	78.8	71.6	50° 10 kt	16	1002
23:00 UTC	78.8	71.6	50° 10 kt	16	1002
23:15 UTC	75.2	71.6	30° 14 kt	19	1002
23:20 UTC	75.2	71.6	30° 14 kt	19	1002
23:35 UTC	75.2	69.8	30° 14 kt	20	1002.7
23:40 UTC	75.2	69.8	30° 14 kt	20	1002.7
23:55 UTC	71.6	66.2	40° 16 kt	22	1002.4
00:00 UTC	71.6	66.2	40° 16 kt	22	1002.4

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Minneapolis radar (KMPX), 93 km away, was scanning. The volume nearest the touchdown began at 22:06 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)	Report	Where	County	Remark
22:08 UTC	FUNNEL CLOUD	Courtland	Nicollet, MN
22:09 UTC	TORNADO	3 W Courtland	Brown, MN	TORNADO OBSERVED BY NUMEROUS STORM SPOTTERS JUST WEST OF THE MINNESOTA RIVER AND NORTH OF STATE HIGHWAY 68. THE TORNADO CROSSED THE RIVER INTO NICOLLET COUNTY WEST OF COURTLAND SHORTLY THEREAFTER.
22:33 UTC	TORNADO	2 Nw North Mankato	Nicollet, MN
22:33 UTC	TORNADO	2 S Nicollet	Nicollet, MN	NUMEROUS REPORTS FROM SPOTTERS AND CHASERS.
22:39 UTC	TORNADO	1 E Nicollet	Nicollet, MN	NWS VOLUNTEER REPORTED STOVE TYPE TORNADO WITH MULTIPLE VORTICIES.
22:53 UTC	TORNADO	St Peter	Nicollet, MN	TORNADO VERY NEAR ST PETER. MULTIPLE REPORTS.
22:55 UTC	TORNADO	1 S St Peter	Nicollet, MN	TREES AND POWER LINES DOWN JUST SOUTH OF ST PETER. POWER SUBSTATION HIT 1 SE OSHAWA.
23:00 UTC	TORNADO	Kasota	Le Sueur, MN	STRUCTURAL DAMAGE IN TOWN.
23:24 UTC	TSTM WND DMG	3 N Elysian	Le Sueur, MN	FARMHOUSE DETROYED.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the track Every 2006 tornado in Minnesota Every tornado in Minnesota since 1950 Warnings in force in Minnesota now The forecast where you are

The other tornadoes of August 24, 2006

14 more were confirmed in the United States that day.

Date	Time	Rating	Where	Path (mi)	Width (yd)	Deaths	Injuries	Damage
August 24	1:01 PM CDT	F0	Morton, ND	0.8	50			$40,000
August 24	1:55 PM CDT	F2	McLean, ND	2.0	90			$200,000
August 24	4:00 PM EDT	F0	Martin, FL	0.3	30			$20,000
August 24	3:03 PM CDT	F0	Kidder, ND	1.0	40
August 24	4:40 PM CDT	F1	Sully, SD	5.0	600
August 24	5:03 PM CDT	F3	McPherson, SD	14.0	300		1
August 24	5:13 PM CDT	F0	Hyde, SD	0.5	20
August 24	5:30 PM CDT	F3	Nicollet, MN	33.0	880	1	37	$24 million
August 24	5:33 PM CDT	F0	Hyde, SD	0.5	20
August 24	6:07 PM CDT	F2	Hand, SD	5.0	300
August 24	6:28 PM CDT	F3	Hand, SD	24.5	500		2	$15 million
August 24	7:18 PM CDT	F2	Beadle, SD	7.0	300			$2.0 million
August 24	7:23 PM CDT	F0	Beadle, SD	0.1	50
August 24	7:56 PM CDT	F0	Kingsbury, SD	0.1	50

What this means

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.