Alert archive / Montana / Severe Thunderstorm Watches in 2002

Severe Thunderstorm Watch 451

June 21, 200216 counties in Montana

The Storm Prediction Center issued this severe thunderstorm watch at Jun 21, 2002, 3:15 PM MDT for 16 counties in Montana. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jun 21, 2002, 3:15 PM MDT (21:15 UTC)
Expired: Jun 21, 2002, 9:00 PM MDT
In force: 6 hr
Issued by: the Storm Prediction Center

Counties Carter County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Rosebud County, MT, Sheridan County, MT, Treasure County, MT, Valley County, MT, Wibaux County, MT

The radar

The Glasgow radar (KGGW), 120 km from the middle of the area, began a volume at 21:36 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.

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jun 21, 3:34 PM MDT	Severe Thunderstorm Warning	BYZ	Big Horn, Treasure	56 min
Jun 21, 3:54 PM MDT	Severe Thunderstorm Warning	BYZ	Rosebud	66 min
Jun 21, 5:00 PM MDT	Severe Thunderstorm Warning	BYZ	Rosebud	60 min

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 9.3 hours before the alert went out and 120 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2135 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 78 m²/s²
0-3 km storm-relative helicity: 95 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WWUS20 KWNS 212053
SEL1  
SPC WW 212048
MTZ000-220300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 451
STORM PREDICTION CENTER NORMAN OK
248 PM MDT FRI JUN 21 2002

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

   EASTERN MONTANA                            

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 315 PM UNTIL 900
PM MDT.

HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 80 STATUTE MILES
EAST AND WEST OF A LINE FROM 55 MILES NORTH NORTHEAST OF GLASGOW
MONTANA TO 30 MILES SOUTH SOUTHWEST OF BROADUS MONTANA.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.  SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
TORNADOES.


DISCUSSION...THUNDERSTORMS HAVE RAPIDLY INTENSIFIED OVER ROSEBUD
COUNTY MT ALONG OUTFLOW FROM EARLIER STORMS THAT DEVELOPED OVER THE
BIG HORN MTNS.  SATELLITE SHOWS OTHER HIGH BASED CELLS DEVELOPING
AHEAD OF SHORT WAVE TROUGH MOVING NEWD ACROSS WY INTO CENTRAL/ERN
MT.  LOW LEVEL SELY WINDS HAVE TRANSPORTED MOISTURE INTO ERN MT
WITH DEW POINTS IN THE 60-64F RANGE...CONTRIBUTING TO MODERATE
INSTABILITY.  WIND PROFILES EXHIBIT STRONG DIRECTIONAL SHEAR WITH
HEIGHT INDICATING POTENTIAL FOR SUPERCELLS.


AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 3 INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM
MOTION VECTOR 22030.


...WEISS

450,1071 485,1075 485,1042 450,1040

Nearby

Severe Thunderstorm Watches in Montana, 2002 Every severe thunderstorm watch 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.