Monsoon moisture brought several pushes of moisture to the region which brought heavy rainfall to most areas, with the daily record in Boise set.
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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 BOI wrote it up.
Monsoon moisture brought several pushes of moisture to the region which brought heavy rainfall to most areas, with the daily record in Boise set.
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 Boise, ID wrote its last area forecast discussion before the first event at Aug 26, 2:11 AM MST, 4 hours 9 minutes earlier.
Area Forecast Discussion...Corrected National Weather Service Boise ID 311 AM MDT Sat Aug 26 2023 .SHORT TERM...Today through Monday night...Showers and isolated thunderstorms have continued through the night from NV northeastward across the ID border into Owyhee County, the western Magic Valley, and Camas Prairie, most closely approximated by the HRRR hi-res model. HRRR shows a decrease in activity around sunrise but then a resurgence this afternoon, and continuing until sunset in Twin Falls County. HRRR also shows thunderstorm outflow winds up to 50 mph. Several models also forecast thunderstorms this afternoon is Baker County/OR as an upper level impulse ejects from a larger upper low in the Pacific near 43/135W. After today's showers and thunderstorms, Sunday looks quieter but also a little hotter as an upper ridge builds northward through the Great Basin. The main part of the ridge will stay in the southwestern US and extend across southern California and into the Pacific. In that position it will block any northward surge of monsoon moisture, so Monday should also be sunny and hot before a cooling Pacific upper trough comes in from the northwest Tuesday. .LONG TERM...Tuesday through Saturday...A Pacific cold front will bring much cooler and breezy weather to our area Tuesday afternoon and evening, as an upper level trough follows the front inland. Our southern zones will remain warm and mostly dry on Tuesday, but expect scattered showers and isolated thunderstorms in Baker County/Oregon and the central Idaho mountains as the cooler air arrives in those areas. Showers will end in the north Tuesday night, and winds will diminish area-wide. Wednesday will be 10-15 degrees cooler under dry westerly flow aloft. As the next trough moves inland on Thursday, little change is expected, with no precipitation and little variation in temperatures. Confidence is lower Friday and Saturday as deterministic models as well as ensemble clusters diverge. However, the ensemble blend shows an upper level ridge forming over the Intermountain Region, which would lead to a warming trend. && .AVIATION...Mainly VFR. Isolated showers and thunderstorms this morning, increasing in coverage this afternoon and continuing through this evening. Thunderstorms will be capable of outflow wind gusts up to 40kt during the afternoon. Surface winds variable 5-10 kt. Winds aloft at 10k feet MSL: S-SW 5-15 kt. Sunday Outlook...Mainly VFR and mostly clear. Surface winds variable 5-15 kt. For KBOI...TODAY: VFR with mid-level clouds. Higher density altitude due to slightly hotter afternoon temperatures. A 20% chance of showers and thunderstorms until around 15z, then 10-20% chance of thunderstorms in the afternoon (22z- 24z). Thunderstorms will be capable of outflow wind gusts up to 25kt this morning and up to 40kt this afternoon. Surface winds variable 5-10 kt. Winds aloft at 10k feet MSL: S-SW 5-15 kt. SUNDAY: VFR and mostly clear. Higher density altitude due to hotter afternoon temperatures. Surface winds SE around 5 kt in the morning, then NW 5-10 kt in the afternoon. Winds aloft at 10k feet MSL: S-SW 5-10 kt. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && www.weather.gov/Boise www.facebook.com/NWSBoise www.twitter.com/NWSBoise SHORT TERM...LC LONG TERM....JT AVIATION.....JT
The national radar mosaic for the moment the first event began.
4 heavy rain. Local standard time, as filed.
The mesonet station FW9039 in Boise measured 1.25 inches of heavy rain.
The mesonet station CW0406 Pine measured 1.56 inches of heavy rain.
The official NWS measurement after a 24 hour period was 2.42 inches of rain.
The mesonet station LLAI1 at Boise measured 2.42 inches of heavy rain.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2023Every state in 2023This day in weather historyWarnings in Idaho, August 2023
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: 1124935, 1124930, 1124932, 1124934.