Heavy rain fell on burn scars from wildfires in the West Central Mountains caused debris flows on US Forest Service roads in the Payette National Forest.
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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.
Heavy rain fell on burn scars from wildfires in the West Central Mountains caused debris flows on US Forest Service roads in the Payette National Forest.
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 Sep 15, 7:29 PM MST, 4 hours 31 minutes earlier.
Area Forecast Discussion National Weather Service Boise ID 829 PM MDT Sun Sep 15 2024 .DISCUSSION...Strong wind gusts and thunderstorms this evening. Gusts up to 60 mph from the north recorded near Farewell Bend, OR, with blowing dust at Ontario. Isolated thunderstorms developed randomly throughout the CWA this evening, still ongoing and moving rapidly north. Associated wind gusts near 50 mph at Twin Falls and east of McCall. Current forecast is in good shape with showers and isolated thunderstorms gradually increasing through Monday, then heavier and more numerous showers and much cooler Monday night and Tuesday in our Idaho zones, as a moist upper low moves from northern Nevada across southeast Idaho. No updates needed. && .AVIATION...Mostly VFR. Areas of MVFR in scattered showers and isolated thunderstorms through the night. Surface winds: generally N to NW 10-20 with gusts to 30 kt, becoming variable 5-15 kt after 08Z. Winds at 10kft: E through S 10-25 kt. KBOI...VFR. A 30 percent chance of showers after Mon/06Z. Surface winds: NW 10-15 kt with gusts to 25 kt through 05Z, then decreasing to less than 10 kt after 08Z. && .PREV DISCUSSION... SHORT TERM...Tonight through Tuesday night... KEY POINTS *This afternoon scattered showers in southeast Oregon, thunderstorms in southeast Oregon and south-central Idaho with heavy rain and strong winds (30-40 mph gusts) the main concern. *Heavy rain in showers and thunderstorms could bring localized flooding on Monday afternoon-evening, mainly in steep drainages and burn scars. *Temperatures will cool, with highs about 10-20 degrees below normal by Tuesday. A deep low becomes closed on the PacNW coast today, and begins to move directly south of our area. This will bring scattered showers to SE OR and isolated thunderstorms to SE OR and S-central ID. Instability is marginal, so if storms develop gusts to 30-40 mph are in the upper end of what would be possible in outflows. Winds will also be breezy tonight in the Lower Snake Plain, with gusts of 20-30 mph. Cloud cover increases to mostly overcast heading into Monday. With the low south of us Monday afternoon and evening, moisture flow and favorable dynamics will bring a stark increase in precipitation chances. While scattered shower coverage decreases in SE OR, coverage in SW Idaho increases to widespread. Decent instability over the West Central Mountains is supportive of thunderstorm development, with most convective allowing models showing a cluster of storms developing Monday afternoon. Gusty winds and heavy rain are again the main concern with storms. Heavy rain over burn scars, especially those in steep terrain, poses a localized flash flood risk. This begins a period of widespread rainfall that lasts through Tuesday evening. Updated rainfall accumulations by the end of Tuesday are 0.5-0.8 inches of rain in mountainous areas, up to 1 inch on ridges, and 0.3-0.5 inches in lower elevations. This continues a trend of accumulation forecasts decreasing, though as the event begins to move into range of convective allowing models we have increasing confidence in our totals. There is still room for the forecast to come down, given the downward trend each run, but unless the position of the low changes major rainfall updates are unlikely. This system will bring a cooling trend as well as increases to surface relative humidities. Highs in the Snake Plain on Tuesday are in the 60s, generally about 15 degrees below normal in the latest forecast. Breezy conditions are expected each afternoon, especially Tuesday as the low exits eastward and another fills in quickly behind it for the long term forecast. LONG TERM...Wednesday through Sunday...An upper level low will move south and east across northern CA and the Great Basin Wednesday and Thursday. The bulk of the moisture associated with this system is expected to remain to our south. However, there is a chance of showers, especially across southern areas closest to the low on Wednesday. Highest pops Wednesday (around 60 percent) will be near the Nevada border and generally 15-40 percent chance elsewhere. Instability is marginal with this system, but enough to justify a slight chance (less than 20 percent) of thunderstorms mainly near the Nevada border. Models generally favor a drying trend from west to east as the upper low moves east Thursday followed by a weak ridge on Friday. Temperatures will remain below normal but trend slightly warmer each day. Forecast confidence is low next weekend but models are showing a weak trough impacting the area in NW flow resulting in low pops (15-30 percent) with northern areas having the best chance of precipitation. Temperatures remain 5 to 10 degrees below normal. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...LC AVIATION.....SP SHORT TERM...JM LONG TERM....TL
Special Weather Statement
National Weather Service Boise ID
714 PM MDT Sun Sep 15 2024
IDZ011-012-033-ORZ062-064-160230-
West Central Mountains ID-Lower Treasure Valley ID-
Upper Weiser River ID-Oregon Lower Treasure Valley OR-
Baker County OR-
714 PM MDT Sun Sep 15 2024
...STRONG WINDS AND BLOWING DUST IN SOUTHWESTERN WASHINGTON AND
NORTHEASTERN MALHEUR COUNTIES THROUGH 830 PM MDT/730 PM PDT/...
At 706 PM MDT/606 PM PDT/, northwest through north winds were
gusting up to 60 mph, with blowing dust reducing visibility to as
low as one mile. These conditions will continue through at least
830 PM MDT /730 PM PDT/.
HAZARD...Wind gusts of 50 to 60 mph.
SOURCE...Surface observations.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Areas of blowing dust reducing
visibilities.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4446 11686 4421 11672 4410 11721 4421 11727
4430 11726 4431 11731
TIME...MOT...LOC 0111Z 247DEG 11KT 4426 11707
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH
LCThe Boise radar (KCBX), 112 km away, was scanning. The volume nearest the first event began at 07:01 UTC.
6 heavy rain, 1 debris flow, 1 thunderstorm wind. Local standard time, as filed.
Debris flows from heavy rain on the Bulldog Fire blocked parts of Forest Service Road 698.
The mesonet station CCDI1 near Anderson Dam measured heavy rain from thunderstorms.
The Deer Haven RAWS measured very strong wind from a thunderstorm outflow boundary.
The mesonet station SQFI1, 8.7 miles East of Glendale, measured heavy rain from thunderstorms.
The mesonet station BRRI1, 9.3 miles North of McCall, measured heavy rain after thunderstorms moved through the area.
The mesonet station, WBRI1, 8.8 miles northwest of Tamarack, measured heavy rain from nearby thunderstorms.
The mesonet station BASI1 measured heavy rain 15.9 miles west of Stanley.
The mesonet station TT433 at the IRAWS 54 measured heavy rain from nearby thunderstorms.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2024Every state in 2024This day in weather historyWarnings in Idaho, September 2024
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: 1209493, 1209485, 1209492, 1209487, 1209488, 1209489, 1209490, 1209491.