Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 128, NWS Great Falls, MT

August 30, 2002Glacier County, Pondera County, Toole County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Aug 30, 2002, 5:15 PM MDT for Glacier County, Pondera County, Toole County, Montana. It was in force for 60 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Aug 30, 2002, 5:15 PM MDT (23:15 UTC)
Expired: Aug 30, 2002, 6:15 PM MDT
In force: 60 min
Issued by: NWS Great Falls, MT
Area: Counties, with a storm outline in the text

Counties Glacier County, MT, Pondera County, MT, Toole County, MT

The radar

The Great Falls radar (KTFX), 137 km from the middle of the area, began a volume at 23:14 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 30, 5:55 PM MDT	Hail 0.75	Valier, MT	A severe thunderstorm produced 0.75 inch hail at Valier 5E.

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, 11.3 hours before the alert went out and 174 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: 15 J/kg
Mixed-layer CIN: -198 J/kg
Mixed-layer LCL: 1839 m above ground
0-6 km bulk shear: 1 kt
0-1 km storm-relative helicity: 46 m²/s²
0-3 km storm-relative helicity: 58 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

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 30, 2:50 PM MDT, 2 hours 25 minutes earlier.

Area forecast discussion, Aug 30, 2:50 PM MDT, 2 hours 25 minutes before

SOUTHWEST AND NORTH CENTRAL MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
250 PM MDT FRI AUG 30 2002

.SHORT TERM...AN UPPER LEVEL LOW PRESSURE TROF OVER THE PACIFIC
NORTHWEST  WILL MOVE OVER THE ROCKIES BY TOMORROW MORNING. THE TROF
IS QUITE WEAK AND VERY LITTLE MOISTURE IS AVAILABLE. SOME
THUNDERSTORM ACTIVITY SHOULD DEVELOP DURING THE AFTERNOON...BUT WILL
HAVE TROUBLE HOLDING TOGETHER ONCE THE HEATING ENDS. WEAK HIGH
PRESSURE WILL BUILD BEHIND THE TROF. AN UPPER LEVEL DISTURBANCE MOVES
ACROSS SOUTHERN ALTA ON SUNDAY. THIS WILL DEVELOP LOW PRESSURE OVER
THE PROVINCE AND GENERATE SOME INCREASED SURFACE WINDS ACROSS THE
NORTHERN AND CENTRAL ZONES. TEMPS WILL TRY TO COOL SLIGHTLY BEHIND
THE TROF SATURDAY ALTHOUGH THE PUSH OF COOLER AIR WILL HAVE TROUBLE
MOVING SOUTH. THE DOWNSLOPE WINDS AND WEAK HIGH PRESSURE ON SUNDAY
WILL ALLOW TEMPS TO WARM AGAIN THRU MONDAY. ZELZER

.EXTENDED...ANOTHER IN A SERIES OF UPPER LEVEL TROUGHS DEVELOPS OVER
THE GULF OF ALASKA BY MONDAY...ROTATES ONSHORE TUESDAY...THEN PUSHES
OVER THE NORTHERN ROCKIES BY THURSDAY. THE ECMWF HOLDS THE TROUGH
BACK OVER THE WESTERN CONUS THROUGH THE WEEK...BUT EXPECT THAT THE
MORE PROGRESSIVE MRF HAS A BETTER HANDLE ON THE SITUATION. THE MRF
SOLUTION WILL DEVELOP SCATTERED CONVECTION OVER THE CWA WEDNESDAY AND
THURSDAY...ALONG WITH COOLER TEMPERATURES AS A SURFACE COLD FRONT
PUSHES THROUGH THE STATE. RIDGING DEVELOPS OVER THE PACIFIC NORTHWEST
ON FRIDAY FOR DRY AND SLIGHTLY WARMER WEATHER. MPJ

.CCF NUMBERS
GTF BB 055/079 048/084 050 13311
    BBBBB 084/048 079/048 074/044 071/043 073 11102332100
CTB BB 050/073 045/078 048 13321
    BBBBB 080/045 076/044 072/042 068/042 071 11102322110
HLN BB 057/082 053/086 054 13421
    BBBBB 087/054 088/052 080/047 076/045 078 11102333200
BZN EB 046/075 045/080 043 13432
    BBBBB 082/044 079/045 076/043 071/041 072 11102343200
WEY EB 036/069 037/073 035 13432
    BBBBB 075/036 077/038 074/036 069/034 070 11102333200
DLN EB 046/075 045/080 044 13432
    BBBBB 082/045 081/045 076/043 070/042 072 11102343100
HVR BB 056/076 050/082 048 13321
    BBBBB 083/048 082/048 078/044 074/043 075 11101333210
LWT BB 052/076 048/080 048 13331
    BBBBB 080/047 080/048 077/045 072/042 073 11101343100

.TFX...NONE.

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 29, 6:17 PM MDT	Flash Flood Warning	TFX	Lewis and Clark	118 min
Aug 30, 4:20 PM MDT	Severe Thunderstorm Warning	TFX	Glacier	55 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.