Alert archive / Montana / Tornado Watches in 2001

Tornado Watch 605

July 21, 200114 counties in Montana

The Storm Prediction Center issued this tornado watch at Jul 21, 2001, 6:30 PM MDT for 14 counties in Montana. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jul 21, 2001, 6:30 PM MDT (00:30 UTC)
Expired: Jul 22, 2001, 12:00 AM MDT
In force: 6 hr
Issued by: the Storm Prediction Center

Counties Big Horn County, MT, Carbon County, MT, Carter County, MT, Custer County, MT, Fallon County, MT, Golden Valley County, MT, Musselshell County, MT, Powder River County, MT, Rosebud County, MT, Stillwater County, MT, Sweet Grass County, MT, Treasure County, MT, Wheatland County, MT, Yellowstone County, MT

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jul 21, 6:31 PM MDT	Severe Thunderstorm Warning	BYZ	Wheatland	59 min
Jul 21, 6:48 PM MDT	Severe Thunderstorm Warning	BYZ	Powder River	57 min
Jul 21, 7:31 PM MDT	Severe Thunderstorm Warning	BYZ	Wheatland	59 min
Jul 21, 7:50 PM MDT	Severe Thunderstorm Warning	BYZ	Golden Valley	25 min
Jul 21, 7:56 PM MDT	Severe Thunderstorm Warning	BYZ	Carter	64 min
Jul 21, 8:18 PM MDT	Severe Thunderstorm Warning	BYZ	Musselshell	57 min
Jul 21, 9:17 PM MDT	Severe Thunderstorm Warning	BYZ	Rosebud	58 min
Jul 21, 10:14 PM MDT	Severe Thunderstorm Warning	BYZ	Rosebud	61 min
Jul 21, 10:32 PM MDT	Severe Thunderstorm Warning	BYZ	Yellowstone	58 min
Jul 21, 11:06 PM MDT	Severe Thunderstorm Warning	BYZ	Custer, Rosebud	54 min
Jul 21, 11:25 PM MDT	Flash Flood Warning	BYZ	Yellowstone	2 hr
Jul 21, 11:32 PM MDT	Severe Thunderstorm Warning	BYZ	Yellowstone	58 min

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 0.5 hours before the alert went out and 262 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: 649 J/kg
Mixed-layer CIN: -90 J/kg
Mixed-layer LCL: 2545 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 2 m²/s²
0-3 km storm-relative helicity: 100 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.7

Open this sounding in Storm Lab

The text

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

000 
WWUS9 KMKC 220010
MKC WW 220005
MTZ000-220600-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 605
STORM PREDICTION CENTER NORMAN OK
605 PM MDT SAT JUL 21 2001

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   SOUTHERN MONTANA                            

EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 630 PM UNTIL
MIDNIGHT MDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 60 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 20 MILES NORTH OF LIVINGSTON MONTANA TO 70
MILES EAST NORTHEAST OF BROADUS MONTANA.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND 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.

OTHER WATCH INFORMATION...  CONTINUE...WW 604...

DISCUSSION...ISOLATED SEVERE THUNDERSTORMS ARE DEVELOPING ALONG THE
BIG HORN MTNS IN SOUTHEAST MT...WHILE OTHER STORMS INTENSIFY OVER
THE MOUNTAINS OF SOUTHWEST MT.  DEEP EASTERLY LOW LEVEL WINDS
THROUGHOUT THIS REGION AND CAPE VALUES OVER 2000 J/KG WILL PROVIDE
FAVORABLE DEEP LAYER AND LOW LEVEL SHEAR FOR SUPERCELLS PRODUCING
DAMAGING WINDS...LARGE HAIL...AND ISOLATED TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. 
MEAN STORM MOTION VECTOR 24030.

...HART

;445,1040 450,1102 465,1102 464,1040;

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 21, 7:45 PM MDT	Severe Thunderstorm Watch	SPC	Daniels, Dawson, McCone, Prairie, Richland, Roosevelt and 2 more	5 hr
Jul 22, 3:00 PM MDT	Severe Thunderstorm Watch	SPC	Big Horn, Carbon, Carter, Custer, Fallon, Golden Valley and 6 more	6 hr

Nearby

Tornado Watches in Montana, 2001 Every tornado watch in 2001

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.