Alert archive / Montana / Severe Thunderstorm Watches in 2001

Severe Thunderstorm Watch 652

August 4, 200119 counties in Montana

The Storm Prediction Center issued this severe thunderstorm watch at Aug 4, 2001, 2:00 PM MDT for 19 counties in Montana. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Aug 4, 2001, 2:00 PM MDT (20:00 UTC)
Expired: Aug 4, 2001, 7:00 PM MDT
In force: 5 hr
Issued by: the Storm Prediction Center

Counties Beaverhead County, MT, Blaine County, MT, Broadwater County, MT, Cascade County, MT, Chouteau County, MT, Fergus County, MT, Gallatin County, MT, Golden Valley County, MT, Hill County, MT, Jefferson County, MT, Judith Basin County, MT, Liberty County, MT, Madison County, MT, Meagher County, MT, Park County, MT, Phillips County, MT, Silver Bow County, MT, Sweet Grass County, MT, Wheatland County, MT

The radar

The Great Falls radar (KTFX), 100 km from the middle of the area, began a volume at 20:04 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

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

Issued	Product	Office	Counties	Lasted
Aug 4, 2:15 PM MDT	Severe Thunderstorm Warning	TFX	Cascade	60 min
Aug 4, 2:18 PM MDT	Severe Thunderstorm Warning	TFX	Jefferson	27 min
Aug 4, 2:29 PM MDT	Severe Thunderstorm Warning	MSO	Silver Bow	61 min
Aug 4, 3:39 PM MDT	Severe Thunderstorm Warning	TFX	Judith Basin	66 min
Aug 4, 3:49 PM MDT	Severe Thunderstorm Warning	TFX	Cascade	26 min
Aug 4, 3:59 PM MDT	Severe Thunderstorm Warning	TFX	Broadwater	31 min
Aug 4, 4:00 PM MDT	Severe Thunderstorm Warning	TFX	Meagher	30 min
Aug 4, 4:09 PM MDT	Severe Thunderstorm Warning	TFX	Cascade	51 min
Aug 4, 4:43 PM MDT	Severe Thunderstorm Warning	TFX	Cascade	32 min

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 8.0 hours before the alert went out and 100 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: 38 J/kg
Mixed-layer CIN: -272 J/kg
Mixed-layer LCL: 2483 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: -70 m²/s²
0-3 km storm-relative helicity: -33 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 
WWUS9 KMKC 041936
MKC WW 041932
MTZ000-050100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 652
STORM PREDICTION CENTER NORMAN OK
132 PM MDT SAT AUG 4 2001

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

   CENTRAL MONTANA                            

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 200 PM UNTIL 700
PM MDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 80
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 85 STATUTE MILES
EAST AND WEST OF A LINE FROM 45 MILES EAST SOUTHEAST OF DILLON
MONTANA TO 45 MILES NORTHEAST OF HAVRE 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 ARE EXPECTED TO CONTINUE TO DEVELOP
ACROSS PARTS OF CENTRAL MT AS SHORTWAVE TROUGH OVER ID MOVES
EASTWARD.  RELATIVELY STRONG MID LEVEL WINDS...COUPLED WITH SBCAPE
VALUES OF 1000-1500 J/KG WILL SUPPORT A FEW SEVERE STORMS PRODUCING
LARGE HAIL AND DAMAGING WINDS.  ACTIVITY MAY BECOME MORE ORGANIZED
BY EARLY EVENING...WITH AN ENHANCED THREAT OF DAMAGING WINDS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70
KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM
MOTION VECTOR 24035.

...HART

;445,1132 485,1105 485,1071 445,1095;

Nearby

Severe Thunderstorm Watches in Montana, 2001 Every severe thunderstorm 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.