Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 103, NWS Great Falls, MT

August 7, 2002Jefferson County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Aug 7, 2002, 4:26 PM MDT for Jefferson County, Montana. It was in force for 49 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: Aug 7, 2002, 4:26 PM MDT (22:26 UTC)
Expired: Aug 7, 2002, 5:15 PM MDT
In force: 49 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), 163 km from the middle of the area, began a volume at 22:28 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
Aug 7, 5:00 PM MDT	Hail 0.75	Boulder, MT	A severe thunderstorm produced 0.75 inch hail in Boulder.

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 12:00Z, 10.4 hours before the alert went out and 194 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1603 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: -43 m²/s²
0-3 km storm-relative helicity: 105 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.

481 
WUUS55 KTFX 072226
SVRTFX
MTC043-072315-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
424 PM MDT WED AUG 7 2002

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  JEFFERSON COUNTY IN SOUTHWEST MONTANA
  THIS INCLUDES THE CITY OF BOULDER

* UNTIL 515 PM MDT

* AT 420 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 19 MILES SOUTH OF BASIN...OR ABOUT 17 MILES
  NORTHEAST OF BUTTE...MOVING NORTHEAST AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  BOULDER AT 440 PM.

THIS STORM CONTAINS HEAVY RAINFALL...HAIL UP TO ONE INCH IN 
DIAMETER...AND WIND GUSTS 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 4604 11245 4583 11229 4596 11187 4638 11182
          4637 11229

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 Aug 7, 3:00 PM MDT, 1 hour 26 minutes earlier.

Area forecast discussion, Aug 7, 3:00 PM MDT, 1 hour 26 minutes before

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
300 PM MDT WED AUG 7 2002

.SHORT TERM...FORTUNATELY ETA AND AVN ARE IN MUCH AGREEMENT TODAY IN
THEIR HANDLING OF THE UPPER TROUGH OVER THE PAC NW. TROUGH IS
FORECAST TO DEVELOP INTO A CLOSED LOW OVER CENTRAL ID BY MORNING
THEN MOVE INTO SW MT THU THEN TRACK E/ENE THU NIGHT INTO FRI.
AIRMASS WILL BECOME EVEN MORE MOIST. SHORTWAVES IN S TO SW FLOW
ALOFT WILL AFFECT THE AREA INTO THU WHEN FLOW ALOFT ALSO BECOMES
DIFLUENT. PRECIPITATION THEN BECOMES WRAP AROUND AS THE UPPER LOW
MOVES ACROSS S CENTRAL MT THU NIGHT. PRECIPITATION THEN SHOULD
DIMINISH/END FRI AS THE UPPER LOW MOVES INTO THE ERN PLAINS OF MT.
MODELS INDICATE QPF TOTALS TONIGHT THROUGH FRI OVER A HALF INCH
OVER MUCH OF THE FORECAST AREA. FERGUS COUNTY COULD SEE TOTALS OVER
2 INCHES. NW PORTIONS OF THE FORECAST AREA SHOULD SEE ONLY LIGHT
AMOUNTS OF RAIN AS THEY WILL BE FARTHER AWAY FROM THE UPPER LOW
AND EVENTUAL WRAP AROUND MOISTURE. EXPECT DRY CONDITIONS FRI NIGHT
AS A TEMPORARY WK UPPER RIDGE MOVES OVER THE AREA. ON SAT ETA/AVN
FLOW ALOFT BECOMES CYCLONIC WLY AHEAD OF THE NEXT UPPER TROUGH WHICH
WILL DROP OVER THE AREA ON SUN. MOISTURE MAY INCREASE OVER THE N ON
SAT BUT LOW LEVEL DOWNSLOPE COULD PREVENT MUCH PRECIPITATION
DEVELOPMENT. STILL WILL MENTION A CHANCE OF SHOWERS OVER THE NRN
ROCKY MOUNTAIN FRONT WITH A SLIGHT CHANCE FOR THE CTB AREA. BLANK

.EXTENDED...
MODELS ARE IN PRETTY GOOD AGREEMENT WITH BRINGING ANOTHER SHOT OF
COOL AND WET WEATHER FOR THE EARLY PART OF NEXT WEEK. COLD FRONT TO
MOVE ACROSS THE CWA ON SUNDAY TRIGGERING SCATTERED SHOWERS. EXPECT
MAINLY AFTERNOON AND EVENING SHOWERS TO CONTINUE MONDAY AND TUESDAY
AS A COOL NORTHWEST FLOW ALOFT PERSIST. 12Z AVN SHOWING SOME RIDGING
ON WEDNESDAY...THEREFORE WILL DRY THINGS OUT ON WEDNESDAY. MEIER

.CCF NUMBERS
GTF RE 050/060 048/071 050 04778
    NEEEB 077/048 067/043 065/043 070/044 074 51114433211
CTB CB 045/063 047/070 048 04633
    NEEEB 072/045 062/040 060/043 065/044 067 11224433211
HLN RB 051/063 048/070 051 04777
    BEEEB 080/048 070/045 070/048 073/047 075 21113322111
BZN WE 050/065 046/067 045 04667
    BEEEB 078/048 070/045 068/048 072/047 072 42113322111
WEY WE 042/060 040/060 036 04666
    BEEEB 070/042 065/040 065/042 067/042 067 32113322111
DLN WB 048/064 045/072 045 04666
    BEEEB 077/048 068/045 069/048 071/047 073 21113322111
HVR RE 052/066 050/074 052 04666
    EEEEB 079/048 067/043 065/045 071/048 074 31114433211
LWT RR 050/062 046/064 046 0477+
    BEEEB 075/048 066/043 066/045 070/048 072 81114433211=

.TFX...NONE.

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 6, 6:14 PM MDT	Tornado Warning	TFX	Fergus	61 min
Aug 7, 5:06 PM MDT	Severe Thunderstorm Warning	TFX	Broadwater	39 min
Aug 7, 5:27 PM MDT	Severe Thunderstorm Warning	TFX	Lewis and Clark	33 min
Aug 7, 5:46 PM MDT	Severe Thunderstorm Warning	TFX	Broadwater, Meagher	59 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.