Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 8, NWS Great Falls, MT

June 21, 2002Jefferson County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jun 21, 2002, 7:39 PM MDT for Jefferson County, Montana. It was in force for 36 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jun 21, 2002, 7:39 PM MDT (01:39 UTC)
Expired: Jun 21, 2002, 8:15 PM MDT
In force: 36 min
Issued by: NWS Great Falls, MT
Area: Counties, with a storm outline in the text

County Jefferson County, MT

The radar

The Great Falls radar (KTFX), 125 km from the middle of the area, began a volume at 01:41 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 21, 8:10 PM MDT	Thunderstorm Wind 52 E	Clancy, MT	A severe thunderstorm produced a 60 mph wind gust at Clancy 6N.

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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Great_falls, MT (KTFX), launched 00:00Z, 1.7 hours before the alert went out and 158 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: 354 J/kg
Mixed-layer CIN: -88 J/kg
Mixed-layer LCL: 2291 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 74 m²/s²
0-3 km storm-relative helicity: 182 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

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

000 
WUUS55 KTFX 220139
SVRTFX
MTC043-220215-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
737 PM MDT FRI JUN 21 2002

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTH CENTRAL JEFFERSON COUNTY IN SOUTHWEST MONTANA

* UNTIL 815 PM MDT

* AT 726 PM MDT...THE PUBLIC REPORTED ONE INCH HAIL NEAR           
  BOULDER...MOVING NORTHEAST AT 25 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  MONTANA CITY AT 750 PM MDT



LAT...LON 4639 11221 4624 11186 4655 11181 4655 11201

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 Great Falls, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 21, 3:00 PM MDT, 4 hours 39 minutes earlier.

Area forecast discussion, Jun 21, 3:00 PM MDT, 4 hours 39 minutes before

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
300 PM MDT FRI JUN 21 2002

.SHORT TERM...A WEAK DISTURBANCE AHEAD OF A LARGE LOW PRESSURE TROF
IS MOVING INTO CENTRAL MT...WATER VAPOR INDICATES A TROF OVER SW MT.
THE MAIN SYSTEM IS OVER NV AND WILL BE MOVING ACROSS SOUTHERN MT
SATURDAY. CURRENTLY...THE CWA IS UNDER A SPLIT IN THE UPPER
LEVEL FLOW WITH MOST DYNAMICS TO THE SOUTH. WEAK RIDGING DEVELOPS
SUNDAY AND MONDAY...THE AIRMASS DRIES SOMEWHAT AND WARMS. AFTERNOON
AND EVENING THUNDERSTORMS TODAY...GREATEST INSTABILITY IS OVER
CENTRAL...SOUTH CENTRAL...AND SOUTHEAST MT. THE AREA OF INSTABILITY
AND DIFFLUENCE ALOFT MOVES EAST BY SUNDAY. WEAK FLOW AT THE SURFACE
UP TO MID LEVELS SHOULD KEEP ANY SEVERE THUNDERSTORM FROM BEING
ORGANIZED OR LONG-LASTING...ALTHOUGH WITH EAST FLOW IN CENTRAL MT AND
SOUTHWEST FLOW OVER SOUTHWEST MT...AN AREA OF CONVERGENCE ALREADY
EXISTS. AND DRY CONDITIONS AT LOWER LEVELS INCREASES THE POSSIBILITY
OF STRONG...GUSTY WINDS NEAR THE THUNDERSTORMS. GENERALLY DRY OVER
NIGHT...THEN MID-LEVEL MOISTURE INCREASES LATE SATURDAY...70-80% RH
SATURDAY NIGHT. 7H LOW PRESSURE TROF ACROSS NW-SE MT...CREATING AN
AREA OF MOISTURE CONVERGENCE AND UPWARD MOTIONS...ACROSS THE SOUTH
EARLY AND SPREADING NORTH. LITTLE CHANGE IN TEMPS FOR THE NEXT FEW
DAYS...THE ADDITIONAL MOISTURE IN THE ATMOSPHERE WILL KEEP OVERNIGHT
TEMPS QUITE MODERATE WHILE TENDING TO HOLD BACK MAX TEMPS. ZELZER

.EXTENDED...NO SIGNIFICANT CHANGES TO THE EXTENDED FORECAST. STRONG
UPPER RIDGE BUILDS OVER WESTERN MONTANA LATE TUESDAY. RIDGE REMAINS
IN PLACE OVER THE CWA THROUGH FRIDAY WITH VERY WARM TEMPERATURES AND
DRY CONDITIONS. GOOD AGREEMENT EXISTS BETWEEN THE ECMWF AND MRF WITH
ONLY MINOR DIFFERENCES IN POSITION OF RIDGE AXIS. MODELS DO TRY TO
BRING WEAK IMPULSES THROUGH THE RIDGE FROM TIME TO TIME THROUGH THE
PERIOD BUT SUBSIDENCE SHOULD BE TOO STRONG TO INITIATE ANY
CONVECTIVE ACTIVITY.

.CCF NUMBERS
GTF TT 054/075 054/080 052 13235
    BBBBB 082/058 088/055 090/055 092/055 092 21121111111
CTB TT 050/074 052/077 050 13136
    BBBBB 080/050 084/052 087/050 088/050 089 31121111111
HLN TT 054/077 054/080 054 13445
    BBBBB 084/056 090/055 092/055 092/055 091 32121111111
BZN TT 050/075 050/075 050 13445
    EBBBB 080/050 088/050 090/050 090/050 089 32121111111
WEY TT 042/068 042/068 042 13555
    EBBBB 072/040 078/040 078/040 079/040 079 32121111111
DLN TT 050/075 050/075 050 13445
    EBBBB 080/050 088/048 088/048 090/048 090 32121111111
HVR TT 055/088 057/088 055 13355
    EBBBB 088/058 090/058 092/058 092/058 092 44121111111
LWT TT 052/075 053/077 052 13455
    EBBBB 079/052 087/052 089/053 090/053 090 32121111111=

.TFX...FLOOD WARNING CONTINUES FOR GLACIER COUNTY
       RIVER STATEMENT FOR NORTHWEST ZONES...SEE FGUS85 KTFX...
       RVSTFX.

The office that day

Everything else NWS Great Falls, MT issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 21, 7:45 PM MDT	Severe Thunderstorm Warning	TFX	Jefferson	30 min
Jun 21, 7:59 PM MDT	Severe Thunderstorm Warning	TFX	Broadwater	31 min
Jun 21, 8:03 PM MDT	Severe Thunderstorm Warning	TFX	Cascade	42 min
Jun 21, 8:07 PM MDT	Severe Thunderstorm Warning	TFX	Lewis and Clark	23 min
Jun 21, 8:08 PM MDT	Severe Thunderstorm Warning	TFX	Cascade	37 min
Jun 21, 8:28 PM MDT	Severe Thunderstorm Warning	TFX	Meagher	32 min
Jun 21, 8:58 PM MDT	Severe Thunderstorm Warning	TFX	Meagher	47 min
Jun 21, 9:11 PM MDT	Severe Thunderstorm Warning	TFX	Cascade, Meagher	64 min
Jun 21, 9:57 PM MDT	Severe Thunderstorm Warning	TFX	Judith Basin	48 min
Jun 22, 2:49 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	26 min
Jun 22, 3:20 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	55 min
Jun 22, 4:19 PM MDT	Severe Thunderstorm Warning	TFX	Blaine	41 min

Nearby

Severe Thunderstorm Warnings in Montana, 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.