A fast-moving low-pressure system from the Canadian prairie generated scattered rain showers and isolated thunderstorms across most of northeast Montana, one of which produced a downdraft wind gust in excess of 60 mph.
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The episode as NWS GGW wrote it up.
A fast-moving low-pressure system from the Canadian prairie generated scattered rain showers and isolated thunderstorms across most of northeast Montana, one of which produced a downdraft wind gust in excess of 60 mph.
The local office's own words before the first event, 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 the first event at May 21, 1:42 PM MST, 23 minutes earlier.
Area Forecast Discussion National Weather Service Glasgow MT 242 PM MDT Sun May 21 2017 .SHORT TERM...for northeast Montana...tonight through Tue... A north central plains low pressure system and its associated short-wave trough on its back-side spinning over the northern high plains region has brought scattered rain showers and isolated thunderstorms to many NE Montana locations today. This activity is expected to continue through tonight as the short-wave trough axis passes over the area. In fact, Monday morning will also see lingering scattered rain showers, although the coverage may be a little less overall, and more concentrated to areas near and south of the Yellowstone River valley as clearing will commence from the NW beginning Monday afternoon. Monday night through Wednesday morning, a ridge of high pressure will be in control over the region with no chance of precipitation for NE Montana. BMickelson .LONG TERM...Tue night through Sun... System moving in for Wednesday and Thursday rather dynamic and stronger than what previous models were showing. Bumped up pops Wednesday afternoon as storms look to fire up in the southeast zones along/ahead of the cold front. Some could be severe. Then windy conditions are expected into Thursday. Lake Wind Advisory looks like a sure bet. TFJ Previous Discussion... The extended period begins Monday night into Tuesday with an upper level ridge advancing across the western U.S. and bringing warmer and drier weather conditions to northeast Montana. The ridge axis will shift east by Wednesday with a low pressure system and surface cold front approaching from southern Canada. Pre-frontal warming may lift high temperatures to around 80 degrees, but increased chances for showers and thunderstorms in the evening and continuing at night are expected with that next system. Gusty west winds are also expected as this system pushes through. Current 00z models have the upper level closed low remaining situated over southern Saskatchewan through the remainder of the upcoming week. The proximity of this system will maintain cooler temperatures across the CWA and maintain chances for showers and perhaps a thunderstorm at times each day. Maliawco && .AVIATION... VFR, isolated lower conditions possible. Scattered showers will gradually diminish from NW to SE tonight. Strong winds will diminish by mid evening. Some sub-VFR clouds may form late tonight in the wake of heavier showers. These clouds will lift Monday morning. TFJ && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Lake Wind Advisory until 10 PM MDT this evening For Fort Peck Lake for Central and Southeast Phillips...Central and Southern Valley...Garfield...McCone...Petroleum. && weather.gov/glasgow
Special Weather Statement National Weather Service Glasgow MT 247 PM MDT SUN MAY 21 2017 MTZ017-022-023-026-212145- Garfield MT-Prairie MT-McCone MT-Central and Southern Valley MT- 247 PM MDT SUN MAY 21 2017 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN GARFIELD...SOUTHWESTERN VALLEY...SOUTHWESTERN MCCONE AND NORTHWESTERN PRAIRIE COUNTIES UNTIL 345 PM MDT... At 247 PM MDT, Doppler radar was tracking a strong thunderstorm near Hell Creek Rec Area, or 25 miles north of Jordan, moving southeast at 35 mph. Half inch hail and winds in excess of 40 mph will be possible with this storm. Locations impacted include... Jordan, The Pines Rec Area, Hell Creek Rec Area, Flowing Wells Rest Area, Cohagen, Nelson Creek Rec Area, Rock Creek Rec Area, Haxby, Watkins and Van Norman. PRECAUTIONARY/PREPAREDNESS ACTIONS... Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. If on or near Fort Peck Lake, get out of the water and move indoors or inside a vehicle. Remember, lightning can strike out to 10 miles from the parent thunderstorm. If you can hear thunder, you are close enough to be struck by lightning. Move to safe shelter now! Do not be caught on the water in a thunderstorm. Persons in campgrounds should consider seeking sturdy shelter until this storm passes. && LAT...LON 4779 10737 4796 10632 4709 10571 4698 10709 TIME...MOT...LOC 2047Z 335DEG 32KT 4768 10680 Proton
The Glasgow radar (KGGW), 50 km away, was scanning. The volume nearest the first event began at 21:06 UTC.
1 thunderstorm wind. Local standard time, as filed.
Public reported a 62 mph wind gust from a downdraft associated with a nearby thunderstorm.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2017Every state in 2017This day in weather historyWarnings in Montana, May 2017
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 688689.