Monsoon moisture combined with unstable conditions associated with an approaching trough and afternoon heating produced strong to severe thunderstorms across parts of Southwest Idaho.
Every event with a place to put it. Tap one for its entry below.
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 combined with unstable conditions associated with an approaching trough and afternoon heating produced strong to severe thunderstorms across parts of Southwest Idaho.
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 30, 1:25 PM MST, 1 hour 35 minutes earlier.
Area Forecast Discussion
National Weather Service Boise ID
225 PM MDT Wed Aug 30 2017
.SHORT TERM...Tonight through Friday...Isolated thunderstorms
have begun to developed across Harney and Malheur Counties and
the Owyhee mountains this afternoon producing brief heavy rain.
Storms are expected to expand in coverage through this evening
bringing brief heavy rain and gusty outflow winds. Given the dry
boundary layer, wind gusts up to 50 mph will be possible with the
stronger storms. Storm will diminish from west to east later this
evening as dry air moves in with the upper level trough and cold
front. Cold frontal passage expected Thursday morning with breezy
northwesterly winds behind the front Thursday afternoon. Upper
level ridge moves inland from the west on Friday for warm and dry
conditions. The ridge will likely trap smoke for nearby fires
creating smokey/hazy conditions. Temperatures cool to near normal
on Thursday but warm back to about 5 degrees above normal by
Friday.
.LONG TERM...Friday night through Wednesday...Strong upper ridge
will shift east across Oregon Saturday bringing clear, hot, and dry
weather to our CWA that will last through Labor Day. Ridge will
remain over the Great Basin Monday through Wednesday allowing
monsoon moisture to spread north into sern Oregon with a slight
chance of thunderstorms there.
&&
.AVIATION...VFR. Thunderstorms in southern Malheur and Harney
Counties moving into southwestern Idaho through 04Z. Storm cores
will have locally heavy rain and outflow wind gusts to 45 kts
through sunset. Clearing west to east after 04Z. Surface winds
generally 10-15kts across higher terrain of southeast Oregon, and
less than 10kts in the Snake Plain and sheltered valleys. Southwest
winds aloft 10kts at 10k feet msl.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...Red Flag Warning until 1 AM MDT Thursday
IDZ401>403-421-423-424-426.
OR...Red Flag Warning until 1 AM MDT /midnight PDT/ Thursday ORZ637.
&&
www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise
SHORT TERM...JDS
LONG TERM....LC/WH
AVIATION.....LCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BOISE ID
340 PM MDT WED AUG 30 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0315 PM TSTM WND DMG BAKER 44.77N 117.83W
08/30/2017 BAKER OR PARK/FOREST SRVC
A TRAINED SPOTTER REPORTED RAINFALL OF 0.10 INCH IN 10
MINUTES, WIND SPEAD AT 12 MPH WITH GUSTS TO 21 MPH , AND
A VERY BIEF PERIOD WITH DIME-SIZED HAIL. BAKER CITY
AIRPORT ASOS REPORTED HEAVY RAIN AND THUNDERSTORMS WITH
WIND FROM THE WEST AT 25 MPH WITH GUSTS TO 35 MPH AND
PEAK GUST OF 48 MPH.
0315 PM TSTM WND GST BAKER 44.77N 117.83W
08/30/2017 M48 MPH BAKER OR PARK/FOREST SRVC
A TRAINED SPOTTER REPORTED A THUNDERSTORM WITH RAINFALL
OF 0.10 OF AN INCH IN 10 MINUTES, WIND STEADY AT 12 MPH
WITH GUSTS TO 21 MPH, AND A BRIEF PERIOD OF DIME-SIZED
HAIL. THE BAKER CITY ASOS REPORTED THUNDERSTORMS AND
HEAVY RAIN WITH WIND FROM THE WEST AT 18 MPH WITH GUSTS
TO 38 MPH AND A PEAK GUST OF 48 MPH.
&&
WHEWKOThe Boise radar (KCBX), 71 km away, was scanning. The volume nearest the first event began at 22:02 UTC.
2 thunderstorm wind. Local standard time, as filed.
Social media posted pictures of utility poles snapped in half near New Plymouth. National Weather Service radar indicated outflow thunderstorm winds were around 50 knots.
The Boise FAA tower reported a 67 MPH wind gust. Multiple damage reports were received in Southeast Boise with large trees and branches down including power outages.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2017Every state in 2017This day in weather historyWarnings in Idaho, August 2017
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: 710961, 710957.