Sustained monsoonal flow brought heavy rains and several areas with flash flooding.
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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 heavy rains and several areas with flash flooding.
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 30, 1:03 PM MST, 1 hour 17 minutes earlier.
Area Forecast Discussion National Weather Service Pocatello ID 203 PM MDT Fri Jul 30 2021 .SHORT TERM...Through Sunday. A low pressure system is advancing northward through Nevada this afternoon. An initial band of showers and thunderstorms associated with that low will affect the southeast highlands this afternoon and then spread southwestward into the south hills. This band of storms is separate from the disorganized isolated to scattered storms that we've seen over the past few days. Given the monsoon moisture entrenched across the region, locally heavy rain is possible with storms throughout the weekend as the low advances northward. Will issue flash flood watches targeting the high country across southeast Idaho into the south hills along with the central mountains. Although highly isolated flooding is possible elsewhere as well. The flash flood watch for the south hills and southeast Idaho will begin this afternoon to account for the initial wave of organized convection. This watch accounts for the Badger Fire burn scar near Oakley which is particularly vulnerable in this regime. As mentioned, the low advances north on Saturday to roughly southwest Oregon. Thunderstorms become more widespread across central and east Idaho. Although the flash flood watch for the central mountains begins this afternoon, the better threat begins Saturday. On Sunday, the low moves into Washington State and gains some upper level support as well. This will help to increase chances areawide. Heavy rain will continue to be possible. Although could be limited if there is residual cloud cover in place from decaying convection from the night before. 13 .LONG TERM...The storm system will begin lifting out on Monday. Continuing the flood watches as models still show thunderstorms around. Tuesday looks drier but another system arrives for mid to late week resulting in renewed chances for thunderstorms. && .AVIATION...Multiple rounds of showers and thunderstorms could impact our TAF sites in the next 24 hours. For now, we are carrying VCTS or VCSH and will amend as needed for direct impacts. IF a heavier shower or storm passes over a particular airport, MVFR to IFR conditions due to heavy rain could occur, along with wind gusts over 30kts and maybe small hail. Keyes && .FIRE WEATHER...A very moist sub-tropical flow will continue across the region through Monday. Multiple disturbances will produce several rounds of showers and thunderstorms into early next week. With this being a strong push of monsoon moisture, heavy rain and the potential for flooding/debris flows is there on recent burn scars or existing fires. Gusty winds over 35 mph and small are also possible with the stronger storms. Screaming message in all this, organized disturbances translating through moist sub-topical environments can produce very heavy rainfall events. Land managers operating in and around fires or burn scars should be extra attentive to developments this weekend. It looks like we cycle back into a drier SW flow/ridge pattern briefly Tuesday followed by a Pacific trough lifting through the region Thursday. Lots of moving parts here folks...stay tuned! Keyes/Huston && .PIH WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Monday evening for IDZ056>064-069- 071>074. &&
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE POCATELLO ID
259 PM MDT FRI JUL 30 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0230 PM HEAVY RAIN 2 NE POCATELLO 42.90N 112.44W
07/30/2021 M0.58 INCH BANNOCK ID TRAINED SPOTTER
&&
CMACKAYSpecial Weather Statement National Weather Service Pocatello ID 309 PM MDT Fri Jul 30 2021 IDZ057-302200- Raft River Region ID- 309 PM MDT Fri Jul 30 2021 ...SPECIAL WEATHER STATEMENT... At 308 PM MDT, Doppler radar was tracking a strong thunderstorm 7 miles northeast of Malta, moving north at 5 mph. Winds in excess of 30 mph will be possible with this storm. This storm will affect Interstate 84 near Yale Road in east central Cassia County. PRECAUTIONARY/PREPAREDNESS ACTIONS... Torrential rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4224 11316 4231 11334 4247 11336 4236 11317 TIME...MOT...LOC 2108Z 184DEG 6KT 4237 11326 Valle
The Pocatello radar (KSFX), 81 km away, was scanning. The volume nearest the first event began at 21:18 UTC.
3 flash flood. Local standard time, as filed.
Significant flash flooding occurred across a gravel road, and water was overtopping a small bridge along a paved road in the area of S 2950 E and Heglar Canyon Road west northwest of Heglar.
Flooding along Trapper Creek Road with excessive runoff from Squaw Creek and Little Squaw Creek drainages. Several inches of rocks, mud and debris on the roadway.
Several washouts along Highway 37 south of Rockland including one along King Lane found in NWS storm survey.
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: 974007, 974005, 974006.