Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 11, NWS Great Falls, MT

June 21, 2002Cascade County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jun 21, 2002, 8:03 PM MDT for Cascade County, Montana. It was in force for 42 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jun 21, 2002, 8:03 PM MDT (02:03 UTC)
Expired: Jun 21, 2002, 8:45 PM MDT
In force: 42 min
Issued by: NWS Great Falls, MT
Area: Counties, with a storm outline in the text

County Cascade County, MT

The radar

The Great Falls radar (KTFX), 40 km from the middle of the area, began a volume at 02:06 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.

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, 2.1 hours before the alert went out and 72 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 220203
SVRTFX
MTC013-220245-

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

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTH CENTRAL CASCADE COUNTY IN CENTRAL MONTANA

* UNTIL 845 PM MDT

* AT 800 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM OVER EXTREME SOUTHWEST CASCADE COUNTY...OR
  ABOUT 22 MILES SOUTH OF CASCADE...MOVING NORTHEAST AT 20 MPH.

* THE SEVERE THUNDERSTORM WILL BE REMAIN OVER...
  RURAL AREAS OF CASCADE COUNTY THROUGH 845 PM.

HAIL UP TO ONE INCH AND WINDS TO 60 MPH AND WINDS TO 60 MPH.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST
OFFICE IN GREAT FALLS.

LAT...LON 4732 11130 4717 11107 4701 11130 4701 11154
          4691 11156 4698 11173

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, 5 hours 3 minutes earlier.

Area forecast discussion, Jun 21, 3:00 PM MDT, 5 hours 3 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, 7:39 PM MDT	Severe Thunderstorm Warning	TFX	Jefferson	36 min
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, 8:07 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.