Strong high pressure was the dominant weather pattern in July, which was occasionally suppressed by passing shortwaves and modest moisture for periods of scattered thunderstorms. Often times, the thunderstorm activity was followed by gusty winds and low relative humidity.
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 TFX wrote it up.
Strong high pressure was the dominant weather pattern in July, which was occasionally suppressed by passing shortwaves and modest moisture for periods of scattered thunderstorms. Often times, the thunderstorm activity was followed by gusty winds and low relative humidity. Both lightning and human caused fires flourished in this environment.
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 Jul 16, 10:20 AM MST, 1 hour 53 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 1120 AM MDT Fri Jul 16 2021 update aviation... .UPDATE... Overall the forecast remains largely on track. Expect high temps across much of the area to range from the upper 80s to mid-90s, which is likely being suppressed a bit by the smoke over the area. There are some mid-level clouds over central MT this morning, and some showers and thunderstorms are still forecast to develop this afternoon. Not looking at high likelihood of severe, but will mainly need to monitor for gusty wind potential and new lightning-caused fire starts. -Kredensor && .SYNOPSIS... Isolated to scattered showers and thunderstorms will once again be possible today and through the early evening hours tonight across portions of the region, especially over the higher terrain of Southwest and Central Montana. Temperatures warm through the weekend, with the hottest day being on Monday of next week as temperatures peak between 95 and 105 degrees. && .AVIATION... 1120 AM MDT Fri Jul 16 2021 (16/18Z TAF period) VFR conditions continue across the area. Mid level clouds and a few light showers will continue across central MT. Widely scattered thunderstorms will develop this afternoon. While thunderstorm coverage will likely be low, gusty and erratic winds from this activity will be more widespread. Areas of smoke/haze continue over the region with surface visibility generally greater than 6SM, but could be lower for a period this morning in areas directly downwind of wildfire activity. db Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .FIRE WEATHER... Thunderstorms of both wet and dry nature will once again be possible across portions of Southwest through North Central Montana, mainly along and southeast of a Lincoln, to Belt, to Hays line. While the highest chance for isolated dry thunderstorms exists across Southwest Montana today, a few storms producing little rainfall can not be ruled out further north. Additional chances for thunderstorms arrive back across the Northern Rockies on Monday, with the best chance and coverage of storms expected on Tuesday as monsoonal moisture lifts northeast from the Great Basin and Desert Southwest. Temperatures will remain hot and afternoon relative humidity low through much of next seven days, with the hottest and driest days being on Sunday and Monday. - Moldan && .PREV DISCUSSION... /ISSUED 509 AM MDT Fri Jul 16 2021/ Today through Saturday...subtle wave lifting northeast within southwest flow aloft will provide another opportunity for showers and thunderstorms across Southwest and portions of Central and North Central Montana through the evening hours tonight, mainly along and southeast of a Lincoln, to Belt, to Hays line. Best chance for these showers and thunderstorms will be during peak heating hours, with the best coverage of precipitation primarily residing over the higher terrain. While isolated dry thunderstorms will be a concern across the region once again, especially over Southwest Montana along and south of the I-90 corridor, PWATs approaching 0.75" (especially over Central and North Central Montana) and slow storm motions are expected to lead to higher chances for wetting rains today and early tonight. Given dry boundary and mid-level layers, denoted within soundings (inverted-v's), concerns for gusty and erratic winds approaching 45-55 mph do exist. High temperatures today will be somewhat "cooler" than Thursday, but remain above normal in the upper 80s to upper 90s. Saturday is expected to be dry day across the Northern Rockies as the upper level ridge amplifies across the western 2/3rds of the CONUS and into Canada, with high temperatures warming into the low 90s to low 100s. Sunday through next Friday...primary concern over the period will be the heat and increasing thunderstorm chances. Upper level ridge will continue to amplify through Monday, before subtle waves and increasing monsoonal moisture begin to lift northeast within the southwest flow aloft. Have maintained the Excessive Heat Watch for eastern portions of Central and North Central Montana from Sunday through Wednesday as this period continues to have the warmest daytime highs, with marginal relief (i.e. low temperatures only falling into the mid-60s to mid-70s) during the overnight hours. High temperatures are still expected to peak during the day on Monday, with most lower elevations rising to between 95 and 105 degrees. The warmest temperatures on Monday are expected across eastern portions of Central and North Central Montana; however, even areas like Great Falls, Helena, and Bozeman could reach or exceed the century mark. Monsoonal moisture will begin to lift northeast from the Desert Southwest and Great Basin during the day on Monday, with isolated chances for showers and thunderstorms across southern portions of Southwest Montana. Shower and thunderstorm chances increase further in both potential and areal extent on Tuesday, with the potential for some storms to produce localized heavy rainfall given forecasted PWATs of over 1". Daily chances for afternoon showers and thunderstorms linger across eastern portions of Southwest through North Central Montana from Wednesday through Friday as the upper level ridge slowly shifts east. - Moldan && .PRELIMINARY POINT TEMPS/POPS... GTF 92 57 96 56 / 10 10 0 0 CTB 89 55 91 53 / 0 0 0 0 HLN 94 60 97 62 / 20 20 0 0 BZN 92 53 96 55 / 20 30 0 0 WYS 83 41 87 41 / 20 10 10 0 DLN 88 51 92 52 / 20 30 0 0 HVR 96 62 99 61 / 10 10 0 0 LWT 90 60 94 59 / 40 20 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... Excessive Heat Watch from Sunday afternoon through Wednesday evening Blaine...Chouteau...Fergus...Hill. && http://www.weather.gov/greatfalls
3 wildfire. Local standard time, as filed.
The Christensen Fire was discovered on July 16th in the Beaverhead/Deer Lodge National Forest. The fire grew to 5,442 acres and was zero percent contained on July 31st. The fire was located near the high profile Trailside and Alder Creek Fires.
The American Fork Fire was a lightning caused incident located in the Crazy Mountains. Only the northwest flank of this fire was located in Meagher County, with a majority of it residing over Park and Sweet Grass Counties. By July 31st, the fire charred 14,397 acres and was only 10 percent contained at that time. This fire merged with the Ohearn Creek Fire on July 18th, 2021. At one point it became a part of the Divide Complex type 1 team managed by the Southern Area Incident Management team.
The lightning caused Black Mountain Fire was discovered on July 17th and grew to 1,021 acres by the end of the month. It was eventually managed by a type one incident team, along with the Alder and Trail Creek Fires, though its impacts were less than those major incidents.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2021Every state in 2021This day in weather historyWarnings in Montana, July 2021
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: 969743, 969752, 972794.