Alert archive / Montana / Tornado Watches in 2001

Tornado Watch 604

July 21, 20019 counties in Montana

The Storm Prediction Center issued this tornado watch at Jul 21, 2001, 3:15 PM MDT for 9 counties in Montana. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jul 21, 2001, 3:15 PM MDT (21:15 UTC)
Expired: Jul 21, 2001, 9:00 PM MDT
In force: 6 hr
Issued by: the Storm Prediction Center

Counties Blaine County, MT, Chouteau County, MT, Fergus County, MT, Garfield County, MT, Hill County, MT, Judith Basin County, MT, Petroleum County, MT, Phillips County, MT, Valley County, MT

The radar

The Glasgow radar (KGGW), 176 km from the middle of the area, began a volume at 21:16 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

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

Issued	Product	Office	Counties	Lasted
Jul 21, 3:32 PM MDT	Severe Thunderstorm Warning	TFX	Judith Basin	43 min
Jul 21, 3:54 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	51 min
Jul 21, 4:33 PM MDT	Severe Thunderstorm Warning	TFX	Judith Basin	42 min
Jul 21, 4:45 PM MDT	Severe Thunderstorm Warning	TFX	Blaine	45 min
Jul 21, 5:04 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	56 min
Jul 21, 5:23 PM MDT	Severe Thunderstorm Warning	GGW	Phillips	67 min
Jul 21, 6:20 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	55 min
Jul 21, 6:22 PM MDT	Severe Thunderstorm Warning	GGW	Petroleum	68 min
Jul 21, 6:29 PM MDT	Severe Thunderstorm Warning	GGW	Phillips	61 min
Jul 21, 6:53 PM MDT	Severe Thunderstorm Warning	GGW	Valley	67 min
Jul 21, 7:06 PM MDT	Severe Thunderstorm Warning	GGW	Garfield	69 min
Jul 21, 7:26 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	64 min
Jul 21, 8:13 PM MDT	Severe Thunderstorm Warning	GGW	Garfield	62 min
Jul 21, 9:00 PM MDT	Severe Thunderstorm Warning	GGW	Petroleum	60 min

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 9.3 hours before the alert went out and 142 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: 21 J/kg
Mixed-layer CIN: -341 J/kg
Mixed-layer LCL: 1692 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: -53 m²/s²
0-3 km storm-relative helicity: 75 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.

022 
WWUS9 KMKC 212054
SEL4  
MKC WW 212050
MTZ000-220300-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 604
STORM PREDICTION CENTER NORMAN OK
250 PM MDT SAT JUL 21 2001

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

   CENTRAL MONTANA                            

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

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

THE TORNADO WATCH AREA IS ALONG AND 75 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 60 MILES SOUTHWEST OF HAVRE MONTANA TO 20
MILES SOUTH SOUTHEAST OF GLASGOW 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 603...

DISCUSSION...AIR MASS HAS CONTINUED TO DESTABILIZE AS LOW LEVEL
ELYS ADVECT MOISTURE INTO CENTRAL MT.  SHEAR PROFILES WILL BECOME
INCREASINGLY FAVORABLE FOR SUPERCELLS AS STORMS DEVELOP OFF HIGHER
TERRAIN.  LARGE HAIL AND ISOLATED TORNADOES ARE POSSIBLE ASSOCIATED
WITH SUPERCELLS.


AVIATION...TORNADOES AND 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 550. 
MEAN STORM MOTION VECTOR 24035.


...HALES

465,1062 465,1104 490,1104 490,1062

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; radar from the NEXRAD Level II archive.