A very dry atmosphere ahead of a cold front, combined with a line of rain showers from the west to produce isolated severe downburst winds in northwestern Garfield County.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS GGW wrote it up.
A very dry atmosphere ahead of a cold front, combined with a line of rain showers from the west to produce isolated severe downburst winds in northwestern Garfield County.
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 Aug 24, 4:30 PM MST, 20 minutes earlier.
Area Forecast Discussion National Weather Service Glasgow MT 530 PM MDT Fri Aug 24 2018 .DISCUSSION... 530PM UPDATE: Changes to the forecast were to split PoPs into 1 hours increments to try to capture the movement of the cold front this evening. Have also added haze into the weather grids to account for the visibility drops from the smoke passage, some of which have reached as low as 2 1/2 miles temporarily. Also updated surface winds with the latest version of the National Blend of Models(NBM). Smokes should clear out slowly through the night and with (some) blue sky visible by tomorrow after sun up. Unfortunately a few models are pointing towards anther round of smoke by Saturday night, but confidence in this is only average. GAH PREVIOUS AFTERNOON DISCUSSION: Headline with this forecast package is that summer will be taking a hiatus. Shallow upper trough over the Pacific Northwest will deepen as it moves east over the next several days. It certainly will bring a fall feel to the air as highs will cool significantly by Monday, and most areas should receive some welcome rainfall by Sunday. Surface low pressure over south-central Sask this afternoon with a cold front moving through the CWA this afternoon will continue moving east. NW winds are ushering in smoke, with visibilities down to 3 to 5 miles at some locations. Radar echoes developing over south-central Montana are forming near this front and are expected to move across the southern zones tonight, producing possible gusty winds out ahead of them, mainly over Garfield county. Saturday, we'll be between systems with the next system to move in Saturday night. Some convection will help to quickly develop rainshowers with the first Wetting Rain expected for many areas in quite awhile (last one for Glasgow was July 10th!). The models seem to be in general agreement on this, with the NAM and ECMWF showing stronger development Sunday morning. Pops have been raised slightly and will likely continue this trend as ingredients come together. No severe thunderstorms are expected, but gusty winds, small hail and brief heavy rains are quite possible. Following this impulse comes another surge of cool air. With evaporative cooling to boot, temps will cool well below normal for Monday - with highs in the 60s - about 15 degrees below normal. Afterwards, conditions will remain cooler than normal but high temps return to the 70s most days with off and on chances of showers. TFJ && .AVIATION... FLIGHT CAT: VFR-IFR DISCUSSION: A cold front will move through the area overnight and may provide some clearing. HAZE/SMOKE: from the Pacific NW fires is moving through and generating MVFR conditions with temporary IFR through the evening hours. A cold front will move through this evening. It should begin clearing this smoke out towards the southeast overnight. By Saturday at sun up mixing should bring conditions back up to VFR in visibility. Some models are pointing towards a return of MVFR smoke by Saturday night although confidence is only average/moderate. WIND: out of the northwest calming to 5 to 10 kts tonight. Increasing to 5 to 15 kts Saturday. TFJ/GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && weather.gov/glasgow
Special Weather Statement
National Weather Service Glasgow MT
509 PM MDT FRI AUG 24 2018
MTZ016-021-022-250015-
Petroleum MT-Garfield MT-Central and Southeast Phillips MT-
509 PM MDT FRI AUG 24 2018
...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL PHILLIPS...
PETROLEUM AND SOUTHWESTERN GARFIELD COUNTIES UNTIL 615 PM MDT...
At 508 PM MDT, Doppler radar was tracking a strong thunderstorm 11
miles northeast of Winnett, moving east at 35 mph.
Wind gusts up to 50 mph will be possible with this storm.
Locations impacted include...
Winnett, Flatwillow, Sand Springs, Devils Creek Rec Area, U L Bend
Rec Area, Edwards, Mosby, Crooked Creek Rec Area, Brusett, Petrolia
Lake, Steve Fork and Cat Creek.
LAT...LON 4758 10818 4765 10719 4686 10736 4685 10789
4682 10785 4676 10783 4675 10862
TIME...MOT...LOC 2308Z 272DEG 33KT 4709 10815
HicksThe national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
South Sawmill Creek RAWS site measured a 66 mph wind gust. Time estimated by radar. Best guess is that this resulted from a downburst from high based rain clouds.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2018Every state in 2018This day in weather historyWarnings in Montana, August 2018
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: 777501.