Alert archive / Montana / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 35, NWS Glasgow, MT

May 20, 2007Dawson County, Prairie County, Montana

NWS Glasgow, MT issued this severe thunderstorm warning at May 20, 2007, 11:57 PM MDT for Dawson County, Prairie County, Montana. It was in force for 63 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 20, 2007, 11:57 PM MDT (05:57 UTC)
Expired: May 21, 2007, 1:00 AM MDT
In force: 63 min
Issued by: NWS Glasgow, MT
Area: Counties, with a storm outline in the text

Counties Dawson County, MT, Prairie County, MT

The radar

The Glasgow radar (KGGW), 169 km from the middle of the area, began a volume at 06:01 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.

The watch it was issued in

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

Issued	Product	Office	Lasted
May 20, 2:33 PM MDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 6.0 hours before the alert went out and 169 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: 343 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 1270 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: -4 m²/s²
0-3 km storm-relative helicity: 64 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.1

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 May 20, 9:16 PM MDT, 2 hours 41 minutes earlier.

Area forecast discussion, May 20, 9:16 PM MDT, 2 hours 41 minutes before

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Hazardous weather outlook, May 20, 8:41 PM MDT, 3 hours 16 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GLASGOW MT
841 PM MDT SUN MAY 20 2007

MTZ021>027-220245-
PETROLEUM-GARFIELD-MCCONE-RICHLAND-DAWSON-PRAIRIE-WIBAUX-
841 PM MDT SUN MAY 20 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST
MONTANA.

.DAY ONE...TONIGHT

A SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL MIDNIGHT. LARGE
HAIL AND DAMAGING WINDS ARE POSSIBLE WITH SOME THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

In the hours before

Local storm report, May 20, 9:27 PM MDT, 2 hours 30 minutes before

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Local storm report, May 20, 9:39 PM MDT, 2 hours 18 minutes before

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Local storm report, May 20, 10:03 PM MDT, 1 hour 54 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
May 20, 7:54 PM MDT	Severe Thunderstorm Warning	GGW	Garfield, Petroleum	66 min
May 20, 8:57 PM MDT	Severe Thunderstorm Warning	GGW	Garfield	63 min
May 20, 9:58 PM MDT	Severe Thunderstorm Warning	GGW	Garfield, McCone, Prairie	62 min
May 20, 11:00 PM MDT	Severe Thunderstorm Warning	GGW	Dawson, McCone, Prairie	60 min
May 21, 12:34 AM MDT	Severe Thunderstorm Warning	GGW	Dawson, Richland	56 min
May 21, 1:14 AM MDT	Severe Thunderstorm Warning	GGW	Richland	46 min

Nearby

Severe Thunderstorm Warnings in Montana, 2007 Every severe thunderstorm warning in 2007

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.