Alert archive / Montana / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 39, NWS Glasgow, MT

June 21, 1999Daniels County, Montana

NWS Glasgow, MT issued this severe thunderstorm warning at Jun 21, 1999, 8:55 PM MDT for Daniels County, Montana. It was in force for 35 min. 3 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: Jun 21, 1999, 8:55 PM MDT (02:55 UTC)
Expired: Jun 21, 1999, 9:30 PM MDT
In force: 35 min
Issued by: NWS Glasgow, MT
Area: Whole counties

County Daniels County, MT

What was reported inside it

Time	Report	Where
Jun 21, 9:12 PM MDT	Thunderstorm Wind 63	Peerless, MT
Jun 21, 9:12 PM MDT	Hail 0.75	Peerless, MT
Jun 21, 9:14 PM MDT	Thunderstorm Wind	Whitetail, 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jun 21, 5:30 PM MDT	Tornado Watch	SPC	6 hr

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 2.9 hours before the alert went out and 100 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: 2240 J/kg
Mixed-layer CIN: -31 J/kg
Mixed-layer LCL: 2482 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 64 m²/s²
0-3 km storm-relative helicity: 119 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 5.5

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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 Jun 21, 8:45 PM MDT, 10 minutes earlier.

Area forecast discussion, Jun 21, 8:45 PM MDT, 10 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 21, 6:12 PM MDT	Severe Thunderstorm Warning	GGW	Petroleum	63 min
Jun 21, 6:32 PM MDT	Severe Thunderstorm Warning	GGW	Garfield	63 min
Jun 21, 6:38 PM MDT	Severe Thunderstorm Warning	GGW	Phillips	62 min
Jun 21, 6:51 PM MDT	Severe Thunderstorm Warning	GGW	Valley	59 min
Jun 21, 6:56 PM MDT	Severe Thunderstorm Warning	GGW	McCone	64 min
Jun 21, 7:01 PM MDT	Severe Thunderstorm Warning	GGW	Prairie	64 min
Jun 21, 7:17 PM MDT	Severe Thunderstorm Warning	GGW	Phillips	63 min
Jun 21, 7:40 PM MDT	Tornado Warning	GGW	Phillips, Valley	65 min
Jun 21, 7:52 PM MDT	Severe Thunderstorm Warning	GGW	Daniels, Roosevelt	63 min
Jun 21, 8:28 PM MDT	Tornado Warning	GGW	Roosevelt	62 min
Jun 21, 8:30 PM MDT	Severe Thunderstorm Warning	GGW	McCone, Richland	60 min
Jun 21, 8:44 PM MDT	Severe Thunderstorm Warning	GGW	Sheridan	61 min

Nearby

Severe Thunderstorm Warnings in Montana, 1999 Every severe thunderstorm warning in 1999

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.