An upper low in Southeast Washington moved southeast across Idaho and kicked off strong to severe thunderstorms across the area.
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.
An upper low in Southeast Washington moved southeast across Idaho and kicked off strong to severe thunderstorms across the area.
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 26, 8:06 PM MST, 50 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BOISE ID 906 PM MDT TUE MAY 26 2015 .DISCUSSION...THUNDERSTORMS CONTINUE ACROSS SOUTHERN MALHEUR COUNTY INTO OWYHEE COUNTY AS WELL AS THE LOWER TREASURE VALLEY THIS EVENING. AT 03Z...RADAR IS SHOWING A SMALL AREA OF THUNDERSTORMS NEAR PARMA...NYSSA AND NEW PLYMOUTH MOVING EAST- SOUTHEAST TOWARDS MIDDLETON...EMMETT AND CALDWELL. LATEST HIGH-RES MODELS ARE SHOWING THESE THUNDERSTORMS REACHING THE BOISE METRO AREA...MAINLY STAR AND EAGLE...IN THE NEXT HOUR OR SO. EXPECT BRIEF HEAVY RAIN AND LIGHTNING. ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVERNIGHT AS THE UPPER LEVEL LOW PRESSURE SYSTEM SHIFTS SOUTHWARD TOWARDS THE FORECAST AREA. BY WEDNESDAY AFTERNOON THE LOW CENTER WILL BE OVER LEWISTON. MORE SHOWERS AND THUNDERSTORMS ARE EXPECTED EARLY WEDNESDAY AFTERNOON ACROSS MOST OF THE AREA. CURRENT FORECAST AS THIS COVERED WELL SO NO UPDATE NEEDED. && .AVIATION...VFR. SCATTERED TO ISOLATED SHOWERS BECOMING NUMEROUS SHOWERS AFTER 18Z MAY 28. ISOLATED THUNDERSTORMS EAST OF A LINE FROM KBKE TO KREO THROUGH 06Z AND POSSIBLY ACROSS IDAHO MTNS OVERNIGHT. ISOLATED THUNDERSTORMS REDEVELOPING AFTER 18Z MAY 28. SURFACE WINDS VARIABLE UP TO 12 KTS EXCEPT STRONGER IN SHOWERS AND THUNDERSTORMS. WINDS ALOFT NEAR 10K FT MSL...WEST 10-15 KTS. && .PREV DISCUSSION... SHORT TERM...TONIGHT THROUGH THURSDAY...UPPER LEVEL LOW WAS CENTERED OVER ERN WASHINGTON AS OF 18Z. THIS WILL MOVE SLOWLY SE AND PASS OVER CENTRAL IDAHO OVERNIGHT BEFORE WEAKENING AND DEPARTING TO THE NE INTO MONTANA BY LATE THU. CONVECTION HAS AGAIN DEVELOPED ACROSS PORTIONS OF THE CWA...MAINLY ON THE IDAHO SIDE AND CONCENTRATED IN OWYHEE COUNTY. AS THE LOW MOVES CLOSER OVERNIGHT...MID-LEVEL TEMPS WILL COOL AND WE EXPECT A BETTER- THAN-NORMAL CHANCE OF OVERNIGHT THUNDERSTORMS. SHOWERS AND STORMS ARE AGAIN FORECAST FOR WED AFTERNOON AND EVENING OVER ALL BUT WESTERN HARNEY COUNTY. THERE WILL BE A MIN IN CONVECTION LATE WED NIGHT THROUGH LATE MORNING THU. BY THU AFTERNOON...THE MAIN CHANCE OF THUNDERSTORMS MOVES BACK TO THE IDAHO SIDE AND NRN BAKER COUNTY. TEMPS WILL REMAIN MUCH LIKE THEY HAVE BEEN OVER THE PAST SEVERAL DAYS WHILE OVERNIGHT LOWS WILL REMAIN VERY CLOSE TO NORMAL...AND A LITTLE LOWER THAN OVER THE WEEKEND. OVERALL... CHANGES TO THE FORECAST WERE MINIMAL. LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...AS THE CLOSED LOW MOVES TO OUR EAST...PRECIP CHANCES RAPIDLY DROP OFF AS A RIDGE BEGINS TO BUILD IN. A FEW ISOLATED SHOWERS IN THE IDAHO CENTRAL MOUNTAINS MAY REMAIN IN THE AFTERNOONS...BUT OTHERWISE A WARMING AND DRYING TREND IS EXPECTED THROUGH THE WEEKEND. SUNDAY LOOKS TO BE THE WARMEST DAY WITH TEMPERATURES 10-15 DEGREES ABOVE NORMAL. NEXT PACIFIC SYSTEM LOOKS TO ARRIVE EARLY NEXT WEEK WHICH WILL DECREASE TEMPERATURES AND INCREASE RAIN CHANCES. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...NONE. OR...NONE. && WEATHER.GOV/BOISE DISCUSSION...JS AVIATION.....VM PREV SHORT TERM...SP PREV LONG TERM....EP/DD
The Boise radar (KCBX), 31 km away, was scanning. The volume nearest the first event began at 03:56 UTC.
1 hail. Local standard time, as filed.
Largest hail 1.5 inches and smallest about a penny at the intersection of Floating Feather Road and Pollard Lane. Reported on social media.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Idaho in 2015Every state in 2015This day in weather historyWarnings in Idaho, May 2015
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: 580695.