Alert archive / Montana / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 130, NWS Glasgow, MT

August 21, 2002McCone County, Montana

NWS Glasgow, MT issued this severe thunderstorm warning at Aug 21, 2002, 4:53 AM MDT for McCone County, Montana. It was in force for 67 min. 2 reports 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 21, 2002, 4:53 AM MDT (10:53 UTC)
Expired: Aug 21, 2002, 6:00 AM MDT
In force: 67 min
Issued by: NWS Glasgow, MT
Area: Whole counties

County McCone County, MT

The radar

The Glasgow radar (KGGW), 88 km from the middle of the area, began a volume at 10:55 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 21, 5:00 AM MDT	Hail 1	Vida, MT
Aug 21, 5:20 AM MDT	Hail 2.75	Vida, MT

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.

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 10.9 hours before the alert went out and 88 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: 41 J/kg
Mixed-layer CIN: -403 J/kg
Mixed-layer LCL: 2487 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 29 m²/s²
0-3 km storm-relative helicity: 182 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 Glasgow, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 21, 2:30 AM MDT, 2 hours 23 minutes earlier.

Area forecast discussion, Aug 21, 2:30 AM MDT, 2 hours 23 minutes before

NORTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
230 AM MDT WED AUG 21 2002

.SHORT TERM...
UPPER LOW HAS CONSIDERABLY SLOWED DOWN...NOW OVER E OREGON...
PUTTING E MT IN A TREMENDOUS UPPER DIVERGENT PATTERN THIS MORNING. AS A
RESULT...SEVERE THUNDERSTORMS WITH HEAVY RAIN HAVE BROKEN OUT. THESE
STORMS HAVE BEEN NEARLY STATIONARY SINCE ABOUT MIDNIGHT...AND
FORTUNATELY OVER A VERY DESOLATE PORTION OF THE CWA. AN AREA ABOUT 20
MILES SOUTH OF GLASGOW...ACCORDING TO RADAR ESTIMATES HAS PICKED UP 11
INCHES OF RAIN.

THE BIGGEST QUESTION IS WHAT HAPPENS IN THE NEXT SEVERAL HOURS. DO THE
CURRENT STORMS LIFT OUT...OR DO THEY CONTINUE IN SCATTERED FASHION OVER
THE CWA?

OVER THE REMAINDER OF THE SHORT-TERM BOTH THE ETA AND AVN ARE IN
AGREEMENT WITH THE GENERAL UPPER PATTERN. THE UPPER LOW IS EXPECTED TO
WOBBLE INTO IDAHO TODAY...THEN WEAKEN AND DRIFT WEST BY THURSDAY.

THETA-E RIDGE IS EXPECTED TO GRADUALLY SHARPEN THROUGH FRIDAY WHILE
THE UPPER LEVEL FLOW IS EXPECTED TO REMAIN FROM THE SW. THEREFORE...
HAVE ADDED MENTION OF THUNDERSTORMS FOR THURSDAY AND FRIDAY ACROSS THE
CWA.

.LONG TERM...
MRF AND ECMWF IN AGREEMENT WITH UPPER LOW THAT IS NEARLY STATIONARY OVER
THE PACIFIC NW FINALLY PULLS OUT EARLY NEXT WEEK. CONFIDENCE IS LOW
THAT SATURDAY WILL REMAIN DRY WHILE A CHANCE OF THUNDERSTORMS FROM
SUNDAY THROUGH TUESDAY LOOKS GOOD AT THE MOMENT.

KGGW TBB /075 055/082 058/081 7643222
     BBBB 051/081 050/084 051/081 052/083 052/ 76223333333
KGDV TBB /082 058/084 058/084 7643222
     BBBB 052/082 050/083 050/082 051/084 051/ 76223333333

.GGW...NONE.

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 20, 11:23 PM MDT	Severe Thunderstorm Warning	GGW	Valley	52 min
Aug 21, 12:18 AM MDT	Severe Thunderstorm Warning	GGW	Valley	57 min
Aug 21, 12:35 AM MDT	Flash Flood Warning	GGW	Valley	6 hr
Aug 21, 1:19 AM MDT	Severe Thunderstorm Warning	GGW	Valley	56 min
Aug 21, 2:19 AM MDT	Severe Thunderstorm Warning	GGW	McCone, Valley	56 min
Aug 21, 2:44 AM MDT	Flash Flood Warning	GGW	McCone	6 hr
Aug 21, 10:20 AM MDT	Flash Flood Warning	GGW	Valley	6 hr

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.