Alert archive / Minnesota / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 34, NWS Duluth, MN

June 24, 2002Cass County, Minnesota

NWS Duluth, MN issued this severe thunderstorm warning at Jun 24, 2002, 10:42 PM CDT for Cass County, Minnesota. It was in force for 48 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jun 24, 2002, 10:42 PM CDT (03:42 UTC)
Expired: Jun 24, 2002, 11:30 PM CDT
In force: 48 min
Issued by: NWS Duluth, MN
Area: Counties, with a storm outline in the text

County Cass County, MN

The radar

The Duluth radar (KDLH), 161 km from the middle of the area, began a volume at 03:44 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 was reported inside it

Time	Report	Where	Remark
Jun 24, 11:00 PM CDT	Thunderstorm Wind 50 E	Walker, MN	Numerous trees were blown down.

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 3.7 hours before the alert went out and 240 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: 2853 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 1414 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 52 m²/s²
0-3 km storm-relative helicity: 173 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 9.8

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Duluth, MN wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 24, 4:00 PM CDT, 6 hours 42 minutes earlier.

Area forecast discussion, Jun 24, 4:00 PM CDT, 6 hours 42 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
400 PM CDT MON JUN 24 2002

MAIN PROBLEM IS CONVECTION THIS EVENING.

.ATTM...VERY UNSTABLE ATMOSPHERE WITH STABILITIES TO -12C.  MOISTURE
IS WAY UP THERE...WITH 850 MB DEW POINTS TO 14C AT MSP THIS MORNING
AND SURFACE DEW POINTS OF 24C AT SEVERAL STATIONS.  THICKNESSES AND
HEIGHTS FALL...AND WE REMAIN IN THE RIGHT-REAR QUADRANT OF A 250 MB
JET.  ABUNDANT SUNSHINE IS DESTABLIIZING THE ATMOSHPERE FURTHER.
HOWEVER...A CAP WILL PERSIST UNTIL ABOUT 00Z THIS EVENING. SATELLITE
IMAGERY SHOWS THIS CAP AS WAVE CLOUDS OVER EASTERN SD AND SOUTHEAST
ND...THAT IS GRAVITY WAVES AT THE INTERFACE OF TWO FLUIDS OF
DIFFERING DENSITIES.  OVER NORTHEAST ND AND SOUTHERN MAN...CUMULUS
HAS YET TO BREAK THIS CAP.  SO...WE WILL SIT AND WAIT TIL 00-01Z.

.TONIGHT...IF CONVECTION STARTS...IT WILL FEED ON ABUNDANT MOISTURE
AND CONTINUE.  THE WOODS AND WEEDS HAVE BEEN ALMOST COMPLETELY
DEFOLIATED BY CATERPILLERS ACROSS MOST OF OUR AREA...SO EVAPO-
TRANSPIRATION BY LEAVES HAS NOT ALLOWED TREES TO PASS MOISTURE UPWARD
THROUGH THEIR TISSUES AND OUT THROUGH THE LEAVES.  THUS THE GROUND
REMAINS SATURATED.  NOR ARE THE WEEDS AND WOODS ABLE TO ADD THE USUAL
MOISTURE FROM THEIR LEAVES TO THE LOWER LEVELS OF THE ATMOSPHERE...TO
FEED CONVECTION. ADDING ALL THIS UP LEADS US TO GO BELOW GUIDANCE
WITH 40 PERCENT POPS.  THE CONSENSUS ON TEMPERATURES IS REASONABLE.

.TUESDAY...WE USE THE THE SAME CATERPILLER ARGUMENTS AS A WEAK
TROUGH CROSSES THE AREA.  WITH CONTINUED FALLING THICKNESSES AND
HEIGHTS...WE EXPECT INSTABILITY AND LESS OF A TENDENCY FOR A CAP.
WE WENT CLOSE TO GUIDANCE WITH 40 PCT POPS.  WE FELT GUIDANCE HIGHS
WERE ABOUT 1C TO 2C LOW.

.TUESDAY NIGHT...WITH DRYING REACHING LOW LEVELS BEHIHD THE LAKE
SUPERIOR LOW...CONVECTION WILL END FROM NORTHWEST TO SOUTHEAST
DURING TUESDAY AFTERNOON AND EVENING...FOLLOWED BY CLEARING AND
RADIATIONAL COOLING.  USING THE CATERPILLER ARGUMENT AGAIN...WE
FEEL THAT GUIDANCE LINGERS SHOWERS A LITTLE TOO LONG.  TEMPERATURES
ARE REASONABLE.

.DLH...NONE.

EOM

The office that day

Everything else NWS Duluth, MN issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 25, 5:49 PM CDT	Severe Thunderstorm Warning	DLH	Pine	56 min
Jun 25, 6:49 PM CDT	Severe Thunderstorm Warning	DLH	Pine	26 min
Jun 25, 6:15 PM CDT	Severe Thunderstorm Warning	DLH	Burnett	45 min
Jun 25, 6:46 PM CDT	Severe Thunderstorm Warning	DLH	Douglas	59 min

Nearby

Severe Thunderstorm Warnings in Minnesota, 2002 Every severe thunderstorm warning in 2002

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.