A upper level low centered over west-central Washington State at 6 am MDT on July 14 slowly moved eastward across western Montana by 6 am on July 15. Due to the above normal amounts of atmospheric moisture with origins from the sub-tropics, the thunderstorms produced very heavy rainfall in a short amount of time.
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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 MSO wrote it up.
A upper level low centered over west-central Washington State at 6 am MDT on July 14 slowly moved eastward across western Montana by 6 am on July 15. Due to the above normal amounts of atmospheric moisture with origins from the sub-tropics, the thunderstorms produced very heavy rainfall in a short amount of time.
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 Jul 14, 9:47 AM MST, 3 hours 13 minutes earlier.
Area Forecast Discussion National Weather Service Missoula MT 1047 AM MDT Mon Jul 14 2014 .UPDATE...Added a flash flood watch for flood prone burn scars in Flathead, Mineral, and Missoula counties in addition to the one already in place for Lemhi county. && .DISCUSSION...A second wave of thunderstorm activity is expected to develop this afternoon across much of western Montana and north central Idaho. There are a few concerns with the storms that develop. 1) Potential for a few storms to become strong to severe, capable of producing frequent lightning, hail, and strong winds. The main area of concern for the strong storms is along the Idaho/Montana border into southwest Montana including Ravalli, Lemhi, Granite, Silver Bow and Deer Lodge Counties. There is some potential that a few stronger storms could form outside of this area, towards Flathead County as well, though confidence in this area is not as high at this time. 2) Under the core of thunderstorms, very heavy rain is possible. This could pose a risk to flood prone areas such as recent burn scars (the Mustang, Lolo Creek, West Mullan) as well as the Going- To-The-Sun Road in Glacier National Park. Therefore a flash flood watch has been issued to address concern of flash flooding and debris flows in these locations if they take a direct hit this afternoon/evening. && .AVIATION...Showers and isolated thunderstorms have already begun to form across much of western Montana and north central Idaho this morning. Thunderstorm activity is only going to increase through the afternoon and evening. Thunderstorms this afternoon will be capable of heavy rain locally lowering visibility, frequent lightning, hail and gusty erratic winds. The strongest storms are expected near KBTM and KSMN likely between 14/1900z and 15/0000z. KMSO and KGPI could also experience thunderstorms though the strength is still somewhat in question. Thunderstorms near KGPI could last until later in the evening, possibly as late as 15/0600z. && .PREV DISCUSSION... /ISSUED 401 AM MDT Mon Jul 14 2014/ DISCUSSION...Cloud cover and a persistent east wind have helped keep the atmosphere decently mixed overnight and prevent much cooling. This will actually help further support thunderstorm development across the area later this afternoon as a sharp upper level weather disturbance moves into the Northern Rockies. Models continue to have a really good handle on the passage of this feature along with the instability and lift it will provide. Similarly, infrared satellite and last night's weather balloon data also confirm the presence of an much higher than normal atmospheric moisture that will be shifted into the region by this weather disturbance. All these factors will combine to produce some intense, very wet thunderstorms; especially across parts of southwest Montana and Lemhi County. In fact, we have determined the threat to the Mustang Burn Area as well as narrow portions of US-93 from Lost Trail Pass to Gibbonsville is sufficiently great that a Flash Flood Watch has been issued for Lemhi County for this afternoon through midnight MDT. The threat for severe weather this afternoon/evening is marginal and likely limited southern Ravalli, northern Lemhi, Granite, Deer Lodge and Silver Bow counties. The key severe threat will be hail near 1 inch in diameter. However the intensely heavy rain is most likely to be the more significant impact with most all storms. Meanwhile farther to the north a second area of showers and thunderstorms are expected to develop a little later in the day and persist into tonight. These storms will also posses the threat for heavy rain, especially since the storm motion is extremely light and no better than 10 knots! Some showers and isolated thunderstorms will be possible even after midnight tonight. Though their intensity of coverage are almost certain to diminish. Redevelopment of thunderstorms is expected across southwest Montana on Tuesday afternoon and there could again be the threat for some brief heavy rain with these storms. Wednesday and Thursday...The ridge of high pressure quickly redevelops and will bring a return to above normal temperatures in the lower to mid 90s. Conditions will for the most part be dry except for a few afternoon showers and thunderstorms along the continental divide. Friday through Sunday...Confidence is increasing for a trof of low pressure quickly skim the region, flatten the ridge and bring a return of normal temperatures for mid July. Normal highs are in the middle 80. The 2 main impacts from this system will be some scattered showers and an increase in breezy westerly winds. These impacts will be felt mainly in Northwest Montana with uncertainty for coverage of precip and intensity of winds. AVIATION...Ridging will continue to dominate the weather this evening. Tonight, expect increasing clouds from an approaching system. A few mountain showers are possible in the vicinity of KSMN overnight, but thunderstorms will start in earnest tomorrow. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && Follow us on Facebook and Twitter! https://www.facebook.com/US.NationalWeatherService.Missoula.gov https://www.twitter.com/NWSMissoula
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
148 PM MDT MON JUL 14 2014
IDZ010-142030-
EASTERN LEMHI COUNTY-
148 PM MDT MON JUL 14 2014
...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL LEMHI COUNTY UNTIL 230 PM
MDT...
AT 142 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 12 MILES SOUTHWEST OF LEADORE...OR 33 MILES EAST
OF CHALLIS...MOVING NORTHEAST AT 40 MPH.
HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.
LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...LEMHI...LEADORE AND
TENDOY.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
IF THREATENING WEATHER APPROACHES YOUR AREA...GO INDOORS AND STAY
AWAY FROM WINDOWS. IF YOU ARE CAUGHT OUTSIDE...MOVE TO A WELL
PROTECTED AREA.
&&
LAT...LON 4454 11377 4499 11366 4493 11347 4486 11344
4484 11338 4479 11333 4483 11327 4483 11324
4478 11313 4475 11311 4442 11356
TIME...MOT...LOC 1948Z 231DEG 36KT 4462 11349The Pocatello radar (KSFX), 184 km away, was scanning. The volume nearest the first event began at 20:00 UTC.
1 heavy rain, 1 hail. Local standard time, as filed.
The weather spotter at the Leadore Ranger Station reported 0.40 of rainfall that fell in less than an hour.
The spotter at the Leadore Ranger Station reported dime to penny size hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2014Every state in 2014This day in weather historyWarnings in Idaho, July 2014
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: 530671, 530669.