Disturbances in the moist and unstable southwest flow aloft spread scattered showers and thunderstorms through the area. Warmer than normal temperatures and dry conditions near the surface caused gusty and erratic winds in association with these storms.
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The episode as NWS TFX wrote it up.
Disturbances in the moist and unstable southwest flow aloft spread scattered showers and thunderstorms through the area. Warmer than normal temperatures and dry conditions near the surface caused gusty and erratic winds in association with these storms.
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 Great Falls, MT wrote its last area forecast discussion before the first event at Sep 6, 2:08 PM MST, 22 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 308 PM MDT Thu Sep 6 2018 .SYNOPSIS... Atmospheric instability is causing isolated showers and thunderstorms, this afternoon. Expect these conditions to continue through the evening hours until about 9 pm. In association with thunderstorm activity, expect winds variable with gusts as high as 40 mph. Friday, expect unseasonably warm temperatures, with a chance of isolated showers and thunderstorms Friday night, as a weak cold front moves through the area. This front will cause temperatures to cool on Saturday. && .DISCUSSION... Tonight through Saturday...Unstable southwest flow will continue to bring chances for isolated thunderstorms tonight. Imagery currently showing some sort of boundary setting up from southwest to central MT. This weak almost warm front feature may be the main focus for storms for tonight. Dry lower levels and low Pwats will provide for more of a dry thunderstorm threat today. Gusty winds and lightning being the main threats. Thunderstorm activity will then diminish shortly after sunset tonight. Similar unstable southwest flow pattern will be found on Friday. Slightly warmer temperatures at the surface and aloft may inhibit convection more than today. Still a slight chance of a very isolated thunderstorm is possible Friday afternoon. A cold front then moves through Friday night through Saturday. Models still trying to figure out how much precip will be found with this front. Currently they have a band of showers and isolated thunderstorms moving through in the morning...with isolated thunderstorms in the afternoon. Breezy winds are still looking likely on Saturday, especially across the Rocky Mountain front and adjacent high plains. Temperatures for Friday will be in the mid to upper 80s, then cool behind the front on Saturday into the 70s and low 80s. Anglin Saturday night through Thursday...Moist west to southwest flow over the region into Sunday, perhaps bringing an isolated afternoon shower or two across Central Montana. Models remain in solid agreement with a continued west-southwest flow through next week. A low pressure system in the Pacific Northwest stagnates offshore and keeps this influence over Montana through the week. With good jet support expect afternoon winds to pick up out of the west, with strongest winds along the Northern Rocky Mountain Front. This system looks to remain stuck in place in one form or another, keeping increased chances for cooler weather and precipitation, especially along the Continental Divide. Temperatures remain in the 70s Sunday, 80s Monday, then fall generally into the 60s Tuesday and beyond. && .AVIATION... Updated 1710Z. VFR conditions will continue through the TAF period. Several disturbances will track across central and southwest MT bringing a threat of isolated to widely scattered showers and thunderstorms. Most shower and thunderstorm activity will develop over the SW MT mountains between 20z/Fri and 03z/Sat, then track east to northeast through central and perhaps north-central MT into the evening and early overnight hours before diminishing. The main threat from these showers and storms will be erratic gusts of up to 40 mph at times, but winds will be light otherwise. Overall, smoke from fires to the southwest may gradually reduce visibility through the period, but significant reductions are not anticipated at least through this period. && .FIRE WEATHER... Unstable and warm southwest flow will bring a few showers and thunderstorms this weekend. These storms will be mainly dry with gusty winds and lightning the main threats. This will increase the potential for lightning strikes to cause new ignitions with rapid spread due to the wind. However, there will likely be a few wet thunderstorms to limit any new fire spread and critical fire weather conditions. Will therefore highlight this threat in the Fire Weather Forecast, but am not anticipating a need for a watch or warning. Similar conditions will be found on Friday...with less thunderstorm activity...but lower RH values and warm temperatures. A cold front will then push through Friday night through Saturday. With will bring breezy conditions...slightly improved (although still low) RH values...and some scattered showers and thunderstorms. Anglin && .PRELIMINARY POINT TEMPS/POPS... GTF 54 87 58 81 / 20 0 20 30 CTB 49 85 54 77 / 10 10 10 30 HLN 51 86 55 80 / 40 10 20 30 BZN 47 85 51 82 / 30 10 10 20 WEY 36 78 40 75 / 10 10 0 20 DLN 46 83 50 80 / 30 10 10 20 HVR 52 88 55 84 / 10 10 20 20 LWT 49 84 55 79 / 20 10 10 20 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && http://www.weather.gov/greatfalls
The Great Falls radar (KTFX), 130 km away, was scanning. The volume nearest the first event began at 21:31 UTC.
1 thunderstorm wind. Local standard time, as filed.
Mesonet Station EKHM8, Elkhorn RAWS - 8 miles west of Townsend. 66 mph thunderstorm wind gust. Time of event is estimated.
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, September 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: 779630.