Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 69, NWS Great Falls, MT

July 17, 2002Cascade County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 17, 2002, 7:50 PM MDT for Cascade County, Montana. It was in force for 40 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: Jul 17, 2002, 7:50 PM MDT (01:50 UTC)
Expired: Jul 17, 2002, 8:30 PM MDT
In force: 40 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), 8 km from the middle of the area, began a volume at 01:51 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
Jul 17, 7:55 PM MDT	Thunderstorm Wind 52 E	Ulm, MT	A severe thunderstorm produced a wind gust of 60 mph at Ulm 1S.

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, 1.8 hours before the alert went out and 67 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: 182 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 3158 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 6 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

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

475 
WUUS55 KTFX 180150
SVRTFX
MTC013-180230-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
750 PM MDT WED JUL 17 2002

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CENTRAL CASCADE COUNTY IN CENTRAL MONTANA
  THIS INCLUDES THE CITY OF GREAT FALLS

* UNTIL 830 PM MDT

* AT 746 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 14 MILES SOUTHWEST OF GREAT FALLS...OR ABOUT 11
  MILES NORTHEAST OF CASCADE...MOVING NORTHEAST AT 10 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  5 MILES SOUTHWEST OF GREAT FALLS...7 MILES SOUTHWEST OF BLACK EAGLE
  AT 830 PM MDT

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 4741 11173 4728 11154 4748 11113 4762 11132

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 Jul 17, 2:40 PM MDT, 5 hours 10 minutes earlier.

Area forecast discussion, Jul 17, 2:40 PM MDT, 5 hours 10 minutes before

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
240 PM MDT WED JUL 17 2002

.SHORT TERM...SOUTHWEST FLOW ALOFT IS CONTINUING OVER THE CWA THIS
AFTERNOON. THE SURFACE AIRMASS REMAINS MOIST AND UNSTABLE...AND
CONVECTION IS ALREADY FIRING OVER THE SOUTHWEST MOUNTAINS AND ALONG
THE ROCKY MOUNTAIN FRONT. EXPECT ISOLATED TO SCATTERED THUNDERSTORMS
THIS EVENING AND THURSDAY EVENING. SEVERE WEATHER SHOULD BE LIMITED
DUE TO WEAK SHEAR AND LACK OF UPPER LEVEL DYNAMICS. SLOW MOVING CELLS
COULD TRIGGER LOCALLY HEAVY RAINS WITH ATTENDANT FLASH FLOOD OR MUD
SLIDE DANGER NEAR BURN AREAS. ON FRIDAY THE MODELS ARE IN GOOD
AGREEMENT...PUSHING A SURFACE COLD FRONT INTO CENTRAL MT FROM THE
WEST...ACCOMPANIED BY AN UPPER LEVEL SHORTWAVE. MODEL LIFTED INDICES
AND CAPE INDICATE THAT THE AIRMASS BECOMES RELATIVELY STABLE AS THE
COLD FRONT PUSHES INTO CENTRAL MT FRIDAY AFTERNOON. ETA/MESO-ETA
MODEL QPF IS FAIRLY IMPRESSIVE...THOUGH LIKELY OVERDONE. TIMING OF
THE UPPER DISTURBANCE VARIES BETWEEN THE ETA/MESO-ETA AND AVN
MODELS...BUT EXPECT SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP
AHEAD OF THE FRONT AS IT MOVES INTO THE REGION. ISOLATED
THUNDERSTORMS REDEVELOP OVER THE SOUTHWEST MOUNTAINS AGAIN ON
SATURDAY...BUT DOWNSLOPE WINDS SHOULD KEEP THE PLAINS DRY. MPJ

.EXTENDED...LIKE YESTERDAY AVN AND ECMWF HAVE SIGNIFICANT
DIFFERENCES BETWEEN THEM. 00Z WED AVN HAS NW FLOW ALOFT OVER THE AREA
EARLY NEXT WEEK WITH UPPER RIDGE AXIS NEAR 120W. 12Z TUE ECMWF HAS
THE UPPER RIDGE AXIS OVER THE WRN U.S. 12Z WED RUN OF THE UKMET
LOOKS MORE LIKE THE AVN THAN THE ECMWF. WILL LEAN TOWARDS THE 00Z
WED AVN RUN FOR THIS FORECAST. IT KEEPS WARM TEMPERATURES THROUGH
TUE WITH COOLING FOR WED. 12Z WED RUN OF THE AVN IS A LOT DIFFERENT
THAN ITS 00Z RUN IN THAT IT HAS MUCH MORE TROUGHINESS OVER WRN CAN
AND THE NW U.S. SUN AND MON. FEEL THIS TROUGHINESS IS OVERDONE BUT
IF IT PANS OUT WILL SEE COOLING AS EARLY AS MON. BLANK

.CCF NUMBERS
GTF BW 062/095 062/090 057 14212
    BBBBB 086/054 085/054 085/054 085/052 082 43111111222
CTB BW 059/092 058/086 055 14212
    BBBBB 083/052 082/052 082/052 082/050 078 43111111222
HLN BW 059/093 060/088 058 14314
    BBBBB 088/055 087/055 087/055 087/054 084 53111111222
BZN BW 054/088 056/085 052 14423
    BBBBB 086/052 085/052 085/052 085/052 083 53211111222
WEY BW 052/083 050/079 047 14334
    BBBBB 078/043 080/043 080/043 080/043 078 53211111222
DLN BW 053/086 054/082 052 14335
    BBBBB 083/051 084/051 084/051 084/051 083 52211111222
HVR BW 058/097 062/095 060 14212
    BBBBB 088/055 087/055 087/055 087/054 083 33211111222
LWT BW 056/090 058/089 056 14312
    BBBBB 084/053 085/053 085/053 085/052 080 34211111222=

.TFX...NONE

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 6:54 PM MDT	Severe Thunderstorm Warning	TFX	Chouteau	36 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.