At least three boats were reported capsized due to winds caused by a thunderstorm on Palisades Reservoir on August 1st. Times are estimated and the exact wind speeds are unknown but a significant event to document.
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The episode as NWS PIH wrote it up.
At least three boats were reported capsized due to winds caused by a thunderstorm on Palisades Reservoir on August 1st. Times are estimated and the exact wind speeds are unknown but a significant event to document.
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 Aug 1, 1:55 PM MST, 3 hours 5 minutes earlier.
Area Forecast Discussion National Weather Service Pocatello ID 255 PM MDT Sat Aug 1 2020 .UPDATE... Minor update to mention isolated thunderstorms across the southeast highlands as radar showing some returns already early this afternoon. 13 && .PREV DISCUSSION... /issued 149 PM MDT Sat Aug 1 2020/ DISCUSSION...Weak shortwave pushing through East Idaho today. Have started to see convection fire across portions of the central mountains ahead of the main shortwave, apparent on satellite imagery. Areal coverage is a little further west than originally anticipated, so have adjusted late afternoon and early evening precip chances upwards slightly, adding "gusty wind" wording as well per yesterday's convective activity. Temperatures remain the main story through Monday as ridge axis remains draped directly over the region. Temperatures are generally on par with the previous day. Southern portions of the Snake Plain are running a few degrees cooler, northern regions of the Snake Plain and much of the higher elevations are generally warmer. Expect similar conditions again both Sunday and Monday while ridge remains in place. Heat Advisories continue through at least Sunday at this time. Cool front still timed for Monday night, with isolated convection possible late Monday and again Tuesday along with an uptick in winds. This should bring a few degrees of temperature relief Tuesday, but trend is still near to above normal most places. Mainly dry conditions remain in place, with temperatures ticking back upwards again. There is a trend to shift trough currently along the Pacific coast slightly inland for Thursday and Friday, which could increase the potential for thunderstorms across more of the region late in the week. DMH AVIATION...Look for VFR conditions across the area. We will continue to see isolated storms developing in some areas through tomorrow. Even then, impacts to any given TAF site would only be sporadic with gusts over 30kts potentially. Keyes FIRE WEATHER...High pressure will slowly break down through Monday. Until then, we are looking for high Haines indices as well as isolated thunderstorms. Although given the extreme heat, a storm could fire anywhere...but the best chance of seeing isolated storms will be over the central mountains and Zone 411. Outflows over 30mph are possible with these storms, including any emerging into the Snake Plain. The risk is still there Sunday but much lower, with a small uptick Monday with the front across portions of the central mountains and along the Montana/Wyoming borders. With that front winds pick up with gusts of 25-35mph common across much of central and eastern Idaho OUTSIDE of thunderstorms. At the moment, we could see critical fire thresholds met across Zones 410 and 425. Moderating temperatures are expected behind the front Tuesday and will remain fairly steady and slightly above climatological norms through Friday as the ridge never fully recovers its former amplitude as weak impulses shift east through the region supporting isolated thunderstorm activity. Keyes/Huston && .PIH WATCHES/WARNINGS/ADVISORIES... Heat Advisory until midnight MDT Sunday night for IDZ051-052- 054>059-075. &&
Special Weather Statement
National Weather Service Pocatello ID
522 PM MDT Sat Aug 1 2020
IDZ063-020000-
Caribou Range ID-
522 PM MDT Sat Aug 1 2020
...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL BONNEVILLE AND
EASTERN BINGHAM COUNTIES UNTIL 600 PM MDT...
At 519 PM MDT, Doppler radar was tracking a strong thunderstorm 11
miles southwest of Irwin, or 12 miles southwest of Swan Valley,
moving southeast slowly.
Winds in excess of 40 mph will be possible with this storm.
Locations impacted include...
Palisades Reservoir, Irwin, Alpine Campground and Alpine Airport.
Boaters on Palisades Reservoir can expect sudden wind gusts
increasing waves and leading to very choppy waters which will result
in hazardous boating conditions. Boaters are urged to seek safe
harbor if possible.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.
&&
LAT...LON 4326 11157 4328 11159 4328 11162 4330 11164
4340 11160 4337 11118 4334 11113 4334 11108
4336 11104 4309 11104
TIME...MOT...LOC 2319Z 296DEG 8KT 4328 11144
TAXThe Pocatello radar (KSFX), 126 km away, was scanning. The volume nearest the first event began at 00:02 UTC.
1 thunderstorm wind. Local standard time, as filed.
At least three boats were reported capsized due to winds caused by a thunderstorm on Palisades Reservoir on August 1st. Times are estimated and the exact wind speeds are unknown but a significant event to document.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2020Every state in 2020This day in weather historyWarnings in Idaho, August 2020
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: 916438.