The combination of above normal mountain snow-pack up to 200% of normal and warmer than normal temperatures in the month of May led to continued and new river flooding. Missoula County reported that the tally for damage was to the amount of $450,000.
Every event with a place to put it. Tap one for its entry below.
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 MSO wrote it up.
The combination of above normal mountain snow-pack up to 200% of normal and warmer than normal temperatures in the month of May led to continued and new river flooding. Missoula County reported that the tally for damage was to the amount of $450,000.
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 Missoula, MT wrote its last area forecast discussion before the first event at May 5, 1:36 PM MST, 7 hours 24 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 236 PM MDT Sat May 5 2018 .DISCUSSION...Plenty of mid to high level clouds have spread across the Northern Rockies today, with light rain falling across northwest Montana, southwest Montana, and north central Idaho. For the most part however, showers are evaporating before they reach the valley floors, creating blustery winds but not much else. Sunday is looking like it will be a much more active day in the afternoon and evening hours. A line of showers will cross central Idaho and western Montana from south to north Sunday morning, then the sun will make a guest appearance for much of the afternoon. This will only help to create more unstable conditions, priming the region for late day thunderstorm activity. Storms should cross central Idaho shortly around or after 3 pm PDT, and then western Montana after 5 pm MDT. The main concerns will be heavy rain, strong winds, and abundant lightning. If you have plans for the second half of the day Sunday, be sure to account for the aforementioned impacts. Showers will linger overnight Sunday into Monday, with steadily drying conditions as we head into Tuesday. In fact, Tuesday should be a warm and dry day. This won't last long, as another round of rain will enter from the west on Wednesday with the passage of a cold front. Beyond Wednesday/Thursday, the forecast models differ majorly from one another, lending to low forecast confidence. Few changes have been made to the forecast beyond Thursday as a result. For more information on flooding, please see the HYDROLOGY portion of this discussion below. && .AVIATION...Cloud cover remains this afternoon and showers continue to develop. Thunderstorms are possible with northwest Montana, central Idaho, and southwest Montana having the highest threat again occurring. KSMN, KBTM, and points between stand the highest potential to see a thunderstorm this afternoon. Outflows from showers and thunderstorms will bring increased winds at times. Another round of showers are possible overnight with continued cloud cover. && .HYDROLOGY...Snowmelt runoff has caused rivers to rise quickly as warm conditions continue across the region. Major mainstem rivers, such as the Clark Fork River above and below Missoula, the Bitterroot River, the Yaak River are all forecast to see significant rises in the next several days. Most notably, the Clark Fork River above Missoula is forecast to reach Major Flood Stage (13 FT) by Friday, May 11th. Needless to say, rivers are on the rise and will continue to run high, fast, and dangerous in the coming days across the entire Northern Rockies region. This includes small streams and creeks as they reach bankfull and spill over their banks. Please be alert to your local bodies of water and ensure you have a plan in the event of flooding. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Flood Watch through Sunday afternoon Kootenai/Cabinet Region. ID...None. &&
The national radar mosaic for the moment the first event began.
8 flood. Local standard time, as filed.
The Yaak River reached minor flood stage and affected low lying areas adjacent to the river.
The Blackfoot River reached minor flood stage and mainly low lying areas were impacted.
Homes and buildings adjacent to Seeley Lake and the Clearwater River were impacted by flooding. Thirteen homes in the Seeley Lake region were under evacuation orders.
The Bitterroot River near Missoula reached minor flood stage which caused field flooding on the east side of Highway 93 both north and south of Lolo. Ground water adjacent to the Bitterroot River flooded the Linda Vista Golf course and nearby homeowner's backyards.
Low lying areas adjacent to the Clark Fork River below Missoula to Frenchtown were flooded. The river also flooded numerous homes in the vicinity of Harpers Road from both surface water and groundwater; some homes were evacuated by Missoula County Sheriff's Department. Sandbagging of homes occurred on Mallard Way to keep from flooding.
The Bitterroot River reached minor flood stage causing the Spring Gulch campground and low lying areas adjacent to the river to flood.
With both the Bitterroot River and Burnt Fork Creek running high, damage to the Lee Metcalf Wildlife Refuge and Whitetail Golf Course occurred. Much of the damage included scouring of pavement in these areas.
Several small creeks including Union and Nevada flooded nearby fields.
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, May 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: 753009, 753010, 753119, 753100, 753132, 753051, 753063, 753955.