Sustained monsoonal flow brought more flooding to southeast Idaho on July 31st.
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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 PIH wrote it up.
Sustained monsoonal flow brought more flooding to southeast Idaho on July 31st.
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 Pocatello, ID wrote its last area forecast discussion before the first event at Jul 31, 2:07 AM MST, 5 hours 23 minutes earlier.
Area Forecast Discussion National Weather Service Pocatello ID 307 AM MDT Sat Jul 31 2021 .SHORT TERM...Today through Monday. General trend of monsoonal moisture in place on southerly flow aloft will continue through the short term period. Flash flood watches remain in effect through Monday for some mountain areas. Have issued a few flash flood warnings the last couple of days with more expected the next three days as the big threat and impact is the high humidity air mass is producing heavy rain where the thunderstorms develop. High temperatures are expected to be cooler the next three days with extensive cloud cover expected through the three days. Winds not expected to be overly strong other than near thunderstorm outflow. GK .LONG TERM...Tuesday through Saturday. Looks like will be drier period with upper level ridging Tuesday with another Pacific wave returning some isolated to scattered showers and thunderstorms Wednesday and Thursday but confidence low in much precipitation from that system. Friday and Saturday look dry. Temperatures will warm back up Tuesday and Wednesday with near normal temperatures through next Saturday. GK && .AVIATION...Wet pattern continues with showers and thunderstorms and a continued threat for heavy rain. Will continue to carry VCSH/VCTS and try to hone in on specifics within the very short term. Localized MVFR/IFR will be possible within strongest cores, and outflows around 30 mph will be possible. DMH && .FIRE WEATHER...Continued moist/humid sub-tropical pattern remains for East Idaho through the weekend into the early part of the week. Showers and thunderstorms are expected to remain a continued threat, and heavy rain is the main concern with potential for flash flooding/debris flows in steeper terrain/burn scars. Outflow winds around 30 mph will be possible, but the main threat and concern is the heavy rain. Flash flood watch remains in effect for most terrain- based areas in East Idaho through Monday. Upper ridge builds through the Great Basin Tuesday, which should shunt the monsoonal flow to the east. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Monday evening for IDZ056>064-069- 071>074. &&
The Pocatello radar (KSFX), 71 km away, was scanning. The volume nearest the first event began at 14:28 UTC.
3 flood, 3 flash flood. Local standard time, as filed.
Significant street flooding in the area of E 17th Street and Ammon Rd.
Significant street and yard flooding occurred in Iona. The intersection of E Lincoln Rd and Crook Rd and the intersection of E Tanner Dr and N Aubree Way were flooded with over 1 foot of water in the roads in some areas.
Significant street and yard flooding occurred on the west side of Idaho Falls including Saddle Court, Troy Ave, and around Skyline High School. Water was over the bottoms of vehicles.
A National Weather Service Storm Survey found evidence of high water along several stretches of Arbon Valley Road. Road and Bridge crews called out to clear off extensive debris caused by the flash flooding on the roadway.
A NWS storm survey found flooding had occurred on Highway 36 with damage to culverts. Idaho Transportation Department was cleaning up debris.
The US Forest Service reported Trapper Creek Road washed out in the area of FS Road 538 to Trout Creek Pass. A 12 foot deep gully was running down the center of the road. This was due to excessive runoff from the burned canyon walls from the Badger Fire burn scar.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2021Every state in 2021This day in weather historyWarnings in Idaho, 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: 974011, 974017, 974018, 974020, 974021, 974022.