An upper low swinging out of the lee side of the Cascades moved into Southwest Idaho spawning a tornado and strong thunderstorms that resulted in localized flash flooding.
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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.
An upper low swinging out of the lee side of the Cascades moved into Southwest Idaho spawning a tornado and strong thunderstorms that resulted in localized flash flooding.
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 Jun 21, 8:38 AM MST, 2 hours 12 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BOISE ID 938 AM MDT SUN JUN 21 2009 .DISCUSSION...THE LATEST STORM TO AFFECT THE AREA HAS WIDESPREAD RAIN OVER THE BAKER COUNTY AREA. SCATTERED SHOWERS COVER THE REST OF THE AREA WITH SOME THUNDER EXPECTED MAINLY OVER THE IDAHO PORTION. THE UPPER TROF ASSOCIATED WITH THIS STORM...CURRENTLY ALONG THE EAST SIDE OF THE CASCADES...WILL SWING EAST WITH THE TROF ALONG THE OREGON/IDAHO BORDER BY MIDNIGHT TONIGHT. DRIER AIR WILL MOVE IN ALONG AND BEHIND THE TROF SHUTTING OFF THE SHOWERS. OVERNIGHT TONIGHT...EXCEPT FOR SOME SHOWERS PERSISTING INTO MONDAY OVER THE MOUNTAINS NORTH AND NORTHEAST OF BOISE. MOST OF THE AREA WILL BEGIN TO SEE A BIT MORE SUNSHINE ON MONDAY WITH MORE SUN TUESDAY. TEMPERATURES WILL BE QUITE COOL MONDAY MORNING OVER THE SOUTHERN HALF OF THE AREA BUT CLOUDS WILL KEEP TEMPERATURES UP OVER THE NORTHERN PORTION. SLOW WARMING TREND TAKES HOLD LATER IN THE DAY MONDAY THROUGH MID WEEK. SOME UNCERTAINTY IN HOW STRONG THE SW U.S. UPPER HIGH WILL GET FOR THE END OF THE WEEK. MORE ON THIS LATER. && .AVIATION...SHOWERS OVER SE OREGON WITH SOME MVFR CONDITIONS WILL CONTINUE THROUGH THE MORNING...AND THEN BREAK UP AND MOVE EAST AND NORTH OUT OF THE AREA BY LATE AFTERNOON. OVER SW IDAHO...SHOWERS AND THUNDERSTORMS WILL INCREASE THROUGH THE DAY...WITH THE STORMS FORMING OVER NEVADA AND MOVING NORTH INTO SOUTHWEST IDAHO BEING THE MOST INTENSE...WITH MVFR AND LOCALLY IFR CONDITIONS POSSIBLE...ALONG WITH GUSTY WINDS AND HAIL. MODERATE SW WINDS ALOFT. LIGHT SURFACE WINDS EXCEPT NEAR THUNDERSTORMS. && .PREV DISCUSSION...ANOTHER ACTIVE WEATHER DAY AS A SHARP SECONDARY TROF AND POTENT VORT MAX SWING ACROSS THE FORECAST AREA FROM OREGON. FEATURE FAIRLY SLOW MOVING BUT YET ALLOWING ISOLATED THUNDERSTORMS TO FORM EVEN AT THIS EARLY HOUR IN PARTS OF SOUTHEAST OREGON. THUNDERSTORMS BECOME MORE WIDESPREAD LATER TODAY AS A JETSTREAK FROM THE EASTERN PACIFIC RACES EAST AND HOOKS UP WITH THE VORT MAX ACROSS NORTHERN NEVADA. BEST CHANCE FOR STRONG TO SEVERE STORMS WILL BE OVER EASTERN IDAHO WHERE SPC HAS REGION OUTLINED FOR SLIGHT RISK OF SEVERE. MODEL SOUNDINGS FOR TWIN FALLS THIS AFTERNOON INDICATE LI/S IN THE MINUS ONE RANGE AND CAPE BETWEEN 500 AND 600 J/KG. AMPLE LOW LEVEL MOISTURE AVAILABLE IN THIS REGION FROM RECENT HEAVY RAINS...THUS STORMS EXPECTED TO FIRE OFF RATHER EASILY THIS AFTERNOON DURING MAX HEATING AND COINCIDING WITH PASSAGE OF VORT MAX AND LEFT ENTRANCE REGION OF THE JET. HAVE INCLUDED ENHANCED WORDING TO ZONES OVER THE WESTERN MAGIC VALLEY TO INCLUDE GUSTY WINDS AND BRIEF HEAVY RAIN. ELSEWHERE...WIDESPREAD CLOUD COVER THIS MORNING ALONG UPPER TROF AXIS SHOULD BREAK UP THIS AFTERNOON ALLOWING FOR CONTINUED CONVECTIVE INSTABILITY...ALTHOUGH BEST DYNAMICS AND SHEAR PROFILES ARE EASTWARD AS MENTIONED ABOVE IN SLIGHT RISK AREA FROM SPC. HEIGHTS AND THICKNESSES DROP OFF SHARPLY TODAY BEHIND COOL TROF...THUS HAVE CONTINUED TREND OF COOLER TEMPERATURES THROUGH MONDAY. REAL WARMUP DOES NOT BEGIN UNTIL TUESDAY WHEN LINGERING EFFECTS OF PERSISTENT NORTHWEST TROF FINALLY EXIT THE AREA. MONDAY A DECENT DAY BUT MOUNTAIN AREAS REMAINED PRONE TO AFTERNOON SHOWER ACTIVITY. LONG TERM...MONDAY NIGHT THROUGH SUNDAY...PRECIPITATION WILL TAPER OFF MONDAY NIGHT AS UPPER LEVEL TROUGH EJECTS TO OUR NORTH. WARMER AND DRIER TUESDAY AND WEDNESDAY WITH FORECAST AREA UNDER SPLIT FLOW - BETWEEN A SYSTEM OFF THE CA COAST AND ANOTHER IN THE GULF OF ALASKA. GULF OF ALASKA TROUGH WILL TRANSITION EASTWARD INTO BRITISH COLUMBIA/ALBERTA ON THURSDAY WITH ASSOCIATED COLD FRONT TRAILING SOUTH INTO THE FORECAST AREA BY THURSDAY AFTERNOON. THEREFORE...HAVE MAINTAINED THE SLIGHT CHANCE TO CHANCE POPS ACROSS NORTHERN TERRAIN THURSDAY NIGHT. MODELS DIVERGE FRIDAY AND BEYOND. BOTH ECMWF AND GFS NOW BRING THE CALIFORNIA LOW NE INTO THE GREAT BASIN OVER THE WEEKEND...BUT DISTINCT DIFFERENCES IN TIMING REMAIN. EITHER WAY...BOTH SATURDAY AND SUNDAY LOOK TO BE COOLER THAN PREVIOUSLY THOUGHT AND HAVE THEREFORE TRENDED BOTH DAYS SEVERAL DEGREES COOLER. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...NONE. OR...NONE. && WEATHER.GOV/BOISE DISCUSSION...PRF AVIATION...TB
HAZARDOUS WEATHER OUTLOOK...CORRECTED NATIONAL WEATHER SERVICE BOISE ID 557 AM MDT SUN JUN 21 2009 IDZ011>016-028>030-ORZ061>064-221200- WEST CENTRAL MOUNTAINS-LOWER TREASURE VALLEY ID-BOISE MOUNTAINS- UPPER TREASURE VALLEY-SOUTHWEST HIGHLANDS-WESTERN MAGIC VALLEY- CAMAS PRAIRIE-OWYHEE MOUNTAINS-SOUTHERN TWIN FALLS COUNTY- HARNEY COUNTY-BAKER COUNTY-MALHEUR COUNTY- LOWER TREASURE VALLEY OR- 557 AM MDT SUN JUN 21 2009 /457 AM PDT SUN JUN 21 2009/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL IDAHO...SOUTHWEST IDAHO...WEST CENTRAL IDAHO...NORTHEAST OREGON AND SOUTHEAST OREGON. .DAY ONE...TODAY AND TONIGHT MORE SHOWERS AND ISOLATED THUNDERSTORMS WILL DEVELOP OVER THE AREA. THESE THUNDERSTORMS MAY BE STRONG OR POSSIBLY SEVERE IN THE TWIN FALLS JEROME AREA THIS AFTERNOON AND EARLY EVENING WITH THE THREAT OF GUSTY WINDS...HAIL AND BRIEF HEAVY RAIN. THE STORM PREDICTION CENTER SAYS THERE IS A SLIGHT RISK OF SEVERE STORMS TODAY IN THE SNAKE RIVER VALLEY GENERALLY EAST OF MOUNTAIN HOME. .SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME BUT COULD BE USEFUL IF STORMS DEVELOP AND BECOME SEVERE. .DAY TWO...MONDAY THROUGH SATURDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME SPOTTER ACTIVATION IS NOT NEEDED
The Elko radar (KLRX), 152 km away, was scanning. The volume nearest the first event began at 17:51 UTC.
1 tornado, 1 flash flood. Local standard time, as filed.
A weak tornado was observed by law enforcement as it moved east northeast across State Highway 51, 4 miles north of the Nevada border. Dust and sage brush were picked up by the tornado and was on the ground for about 1 minute.
A trained spotter reported 1.3 inches of rain in approximately 50 minutes and flash flooding with water running over area roads.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2009Every state in 2009This day in weather historyThe tornado archive for Idaho, 2009Warnings in Idaho, June 2009
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: 179797, 179798.