A funnel cloud formed from a strong thunderstorm just east of Horse Thief Reservoir.
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The episode as NWS BOI wrote it up.
A funnel cloud formed from a strong thunderstorm just east of Horse Thief Reservoir.
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 May 18, 8:56 AM MST, 3 hours 19 minutes earlier.
Area Forecast Discussion National Weather Service Boise ID 956 AM MDT Fri May 18 2018 .DISCUSSION...A few showers and thunderstorms are around the area today, mainly across the Southwest Highlands and into the Boise/West Central Mountains. Models continue to indicate an increase in shower and thunderstorm coverage during the afternoon, with activity waning late this evening. Most activity is confined to southwestern Idaho with a hint of activity across the Treasure/Magic Valley. Rogue shower activity also remains possible over Baker County in Oregon. Drier conditions anticipated on Saturday, with a few showers possible. No changes anticipated to current forecast. && .AVIATION...Mostly VFR. Local mountain obscuration and brief MVFR conditions in heavier showers and thunderstorms. Southeast Oregon: Mainly clear skies except scattered showers and isolated afternoon and evening thunderstorms over Baker County and northern Malheur County. Southwest Idaho: Scattered showers and afternoon and evening thunderstorms over the west central Idaho and Boise Mountains, and isolated showers and thunderstorms over the southwest Idaho highlands. A few thunderstorms could drift southeast across the Snake River Valley late this afternoon and this evening. Surface winds northwest to west 5-15 kts. Gusty and erratic winds possible near showers and thunderstorms. Winds aloft at 10k ft msl northwest 10-20 kts. Weekend Outlook...VFR on Saturday with mainly clear skies, except for isolated afternoon and evening showers and thunderstorms over the mountains. Clouds increasing Saturday night. Numerous showers and scattered afternoon thunderstorms on Sunday, with local mountain obscuration and brief MVFR conditions. && .PREV DISCUSSION... SHORT TERM...Today through Saturday...Upper level trough remains over the region, although a shortwave over Washington/Oregon border will help to push drier air into the region from the west today. This dry slot feature shows up really well on the low level water vapor imagery. Showers and thunderstorms will mainly be confined to Baker County in OR and across the mountains of southwest Idaho during the afternoon. This dry slot will inhibit shower and thunderstorm development across the remainder of SE Oregon and in the Treasure and Magic Valleys of Idaho. On Saturday afternoon, surface dewpoints recover, allowing showers and thunderstorms to develop across the higher terrain areawide, although weak steering flow aloft will keep showers and storms confined to the higher terrain. Temperatures will be around 3-5 degrees above seasonal normals. LONG TERM...Saturday night through Thursday...An upper trough moves into the interior NW on Sunday bringing widespread showers and scattered thunderstorms. The trough will linger over the area through Thursday keeping a chance of showers and thunderstorms. Daytime heating will focus the shower and thunderstorm development across higher terrain during the afternoon/evening. A decrease in coverage is possible Thursday as the trough shifts eastward. Temperatures will continue to run slightly above normal through Thursday. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && www.weather.gov/Boise www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...KB AVIATION.....JT PREV SHORT TERM...KA PREV LONG TERM....DG
The Boise radar (KCBX), 118 km away, was scanning. The volume nearest the first event began at 19:14 UTC.
1 funnel cloud. Local standard time, as filed.
The public sent a picture through social media of a funnel cloud near Horse Thief Reservoir.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2018Every state in 2018This day in weather historyWarnings in Idaho, May 2018
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: 747611.