A non-supercell tornado occurred over far southeastern Lassen County on the evening of the 20th, with a burn scar debris flow on the 21st.
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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 REV wrote it up.
A non-supercell tornado occurred over far southeastern Lassen County on the evening of the 20th, with a burn scar debris flow on the 21st.
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 Reno, NV wrote its last area forecast discussion before the first event at Jul 20, 4:39 PM PST, 1 hour 6 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE RENO NV 539 PM PDT MON JUL 20 2015 .UPDATE... 00Z KREV SOUNDING SHOWED STRONG MID LEVEL CAP IN PLACE WITH LATEST SURFACE ANALYSIS INDICATING DEWPOINTS HAD FALLEN ACROSS MUCH OF WESTERN NEVADA, ESPECIALLY FROM HIGHWAY 50 NORTHWARD. EXTENSIVE HIGH CLOUDS AND AREA OF SUBSIDENCE CONTINUED IN THESE AREAS TO THE NORTH OF LOW. IT IS BECOMING MORE UNLIKELY THAT THUNDERSTORMS WILL DEVELOP IN THESE AREAS TONIGHT. SO WE HAVE ADJUSTED POPS/WX DOWN A BIT. HOHMANN && .SYNOPSIS... LOW PRESSURE OFF THE CALIFORNIA COAST CONTINUES TO PULL MOISTURE NORTH INTO THE EASTERN SIERRA AND WESTERN NEVADA. CHANCES OF RAIN SHOWERS AND THUNDERSTORMS WILL CONTINUE MAINLY THROUGH WEDNESDAY. THUNDERSTORM THREATS INCLUDE THE POTENTIAL FOR LOCALIZED FLASH FLOODING...MAINLY ON TUESDAY...TRANSITIONING TO A WIND AND HAIL THREAT BY WEDNESDAY. FLOW BECOMES DRIER OUT OF THE SOUTHWEST FROM THURSDAY INTO THE WEEKEND. && .PREVIOUS DISCUSSION... /ISSUED 237 PM PDT MON JUL 20 2015/ SYNOPSIS... LOW PRESSURE OFF THE CALIFORNIA COAST CONTINUES TO PULL MOISTURE NORTH INTO THE EASTERN SIERRA AND WESTERN NEVADA. CHANCES OF RAIN SHOWERS AND THUNDERSTORMS WILL CONTINUE MAINLY THROUGH WEDNESDAY. THUNDERSTORM THREATS INCLUDE THE POTENTIAL FOR LOCALIZED FLASH FLOODING...MAINLY ON TUESDAY...TRANSITIONING TO A WIND AND HAIL THREAT BY WEDNESDAY. FLOW BECOMES DRIER OUT OF THE SOUTHWEST FROM THURSDAY INTO THE WEEKEND. SHORT TERM... MOISTURE FROM DOLORES HAS BEEN SLOW TO LIFT INTO THE NORTHERN PORTIONS OF THE SIERRA AND NEVADA. THUNDERSTORMS HAVE FINALLY STARTED OVER MONO COUNTY SHORTLY AFTER NOON; EXPECT COVERAGE TO SPREAD NORTHWARD THROUGH THE EVENING INTO THE OVERNIGHT HOURS. STORM MOTIONS ARE SLOW TOWARDS THE WEST RESULTING IN MORE PROLONGED RAIN REACHING THE GROUND. THIS WILL BECOME INCREASINGLY PROBLEMATIC AS CELLS MOVE OVER TERRAIN AND AS COVERAGE INCREASES. SLOW MOTIONS WILL PROMOTE HEAVIER RAINS AND POTENTIALLY SOME FLASH FLOODING. PWATS WILL REMAIN RELATIVELY HIGH, GREATER THAN 0.7 INCHES AND INCREASING THROUGH MAX HEATING, ON TUESDAY. OF FURTHER CONCERN, THERE APPEARS TO BE A SHARED ENERGY JET REGION DEVELOPING OVER THE NORTH AND CENTRAL SIERRA. THIS WILL PROVIDE A MECHANISM FOR MID LEVEL ASCENT AND UPPER LEVEL DIVERGENCE ENHANCING CONVECTIVE ACTIVITY TUESDAY AFTERNOON. AGAIN, STORM MOTIONS WILL BE RELATIVELY SLOW RESULTING IN A HEIGHTENED THREAT FOR FLASH FLOODING ESPECIALLY IN THE SIERRA AND RANGES NEAR THE SIERRA FRONT. THUNDERSTORMS WILL CONTINUE TO BE A THREAT INTO WEDNESDAY AS A MORE DYNAMIC TROUGH APPROACHES OUT OF THE PACIFIC NORTHWEST. STORM MOTIONS WILL INCREASE, AS WILL THE POTENTIAL FOR INDIVIDUAL CELL ORGANIZATION. THIS PROMOTES FASTER SURFACE WINDS AND LARGER POTENTIAL HAIL GROWTH; SOME CELLS MAY BE SEVERE. THE BEST CHANCES FOR THUNDERSTORM ACTIVITY WILL BE SOUTH OF HIGHWAY 50 THROUGH MONO COUNTY AS WELL AS AREAS EAST OF ALTERNATE HIGHWAY 95. ASIDE FROM THUNDERSTORMS, WINDS WILL BE BREEZY AS THE PRESSURE GRADIENT TIGHTENS. GENERALLY, WINDS WILL GUST UP TO 30 MPH, BUT WIND PRONE AREAS COULD SEE HIGHER GUSTS. BOYD LONG TERM...THURSDAY THROUGH MONDAY... IN GENERAL, DRIER CONDITIONS ARE EXPECTED LATER IN THE WEEK WITH TEMPERATURES SLOWLY WARMING TO NEAR NORMAL FOR FRIDAY AND THROUGH NEXT WEEKEND. HOWEVER, IT IS NOT GUARANTEED THAT EVERY DAY WILL BE FREE OF AFTERNOON CONVECTION, AS SOME MEDIUM RANGE GUIDANCE SCENARIOS FAVOR A POSSIBILITY OF ISOLATED STORMS TOWARD THE WEEKEND. FOR THURSDAY, TROUGH PASSAGE ACROSS THE PACIFIC NORTHWEST WILL BRING SOME LOCALLY BREEZY CONDITIONS. OVERALL IT DOES NOT LOOK TO BE A SIGNIFICANT WIND EVENT, BUT SOME OF THE FAVORED AREAS FROM I-80 NORTHWARD COULD RECEIVE WIND GUSTS NEAR 30 MPH. FARTHER SOUTH WHERE FLOW IS WEAKER, INSTABILITY MAY BE SUFFICIENT TO GENERATE A FEW LATE DAY THUNDERSTORMS SOUTH AND EAST OF A MONO LAKE-WALKER LAKE LINE. AS THIS TROUGH ELONGATES, A WEAK LOW APPEARS TO FORM OFF THE CENTRAL CA COAST BY FRIDAY. THIS LOW IS THEN PROJECTED TO MOVE INLAND TOWARD THE CENTRAL SIERRA. THE ECMWF MOVES IT THROUGH THE SIERRA FRIDAY NIGHT WHILE THE GFS FAVORS A PASSAGE ON SATURDAY. THE GFS SCENARIO IS MORE FAVORABLE FOR PRODUCING CONVECTION SINCE THE FORCING ASSOCIATED WITH THIS LOW WOULD COINCIDE WITH DAYTIME HEATING. SINCE THERE REMAINS UNCERTAINTY IN TIMING AND TRACK OF THIS LOW, WE DID NOT YET ADD MENTION OF THUNDER BUT NUDGED POPS A BIT ABOVE 10% NEAR THE SIERRA AND INTO FAR WESTERN NV FOR SATURDAY AFTERNOON AND EVENING. WE ALSO SPREAD PARTLY CLOUDY ACROSS MOST AREAS SOUTH OF I-80 FOR THIS SAME TIME FRAME. FOR SUNDAY AND MONDAY, DRY AND STABLE CONDITIONS ARE LIKELY TO PREVAIL WITH HIGHS NEAR SEASONAL NORMALS OF LOWER 90S FOR LOWER ELEVATIONS. MEDIUM RANGE GUIDANCE THEN VARIES ON SCENARIOS BY EARLY NEXT WEEK WITH GFS SHOWING ANOTHER TROUGH REACHING THE PACIFIC NORTHWEST, WHILE THE ECMWF EXPANDS THE RIDGE OVER THE CENTRAL US WESTWARD INTO THE GREAT BASIN. FOR NOW WE LEANED SLIGHTLY TOWARD THE GFS WHICH APPEARS TO HAVE MORE ENSEMBLE SUPPORT, RESULTING IN SLIGHT COOLING MONDAY MAINLY NORTH OF I-80 AND IN HIGHER ELEVATIONS WITH A MODEST UPWARD TREND FOR AFTERNOON WINDS. MJD AVIATION... MOISTURE FROM THE REMNANTS OF FORMER HURRICANE DOLORES CONTINUES TO PUSH INTO THE REGION THROUGH MIDWEEK. FOR THE REST OF TODAY, THE BEST CHANCE OF SHOWERS WITH SOME EMBEDDED THUNDERSTORMS WILL BE SOUTH OF HIGHWAY 50, WITH 70% CHANCE OF PRECIP AFFECTING KMMH THRU 04Z. FARTHER NORTH, THE POTENTIAL FOR PRECIP DROPS OFF TO 20-30% AT THE OTHER MAIN TERMINALS. MOST CELLS TODAY WILL BE SHORT LIVED AND SLOW MOVING, WITH DEVELOPMENT DRIVEN MORE BY OUTFLOW INTERACTIONS RATHER THEN ACTUAL CELL MOTION. MAIN AVIATION IMPACTS WILL BE BRIEF REDUCTIONS IN CIGS/VSBY FROM LOCALLY HEAVY RAIN WITH POSSIBLE OUTFLOW GUSTS TO 40 KTS IF A CELL DEVELOPS NEAR OR OVER THE TERMINAL. THE BEST OVERALL CHANCE FOR SHOWERS AND THUNDERSTORMS ARRIVES TUESDAY, WITH BETTER FORCING AND IMPROVED INSTABILITY AS TROUGH APPROACHES THE WEST COAST. POTENTIAL FOR PRECIP AT ALL MAIN TERMINALS 50-60% BETWEEN 18Z-03Z, WITH LOCALLY HEAVY RAIN PRODUCING REDUCED CIGS/VSBY, MTN OBSCURATIONS, AND POSSIBLE OUTFLOW GUSTS TO 40 KTS. MOST CELLS AGAIN WILL BE SLOW MOVING, ALTHOUGH SOME INCREASED MOTIONS ARE POSSIBLE WITH STORMS OCCURRING NORTH OF I-80. BY WEDNESDAY, THUNDERSTORM COVERAGE IS LIKELY TO DECREASE, ALTHOUGH FOR WEST CENTRAL NV SOUTH TO MONO COUNTY A FEW STRONGER CELLS WITH A FASTER MOTION ARE POSSIBLE BY LATE AFTERNOON. MJD && .REV WATCHES/WARNINGS/ADVISORIES... NV...NONE. CA...NONE. && FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT... HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)
The Reno radar (KRGX), 52 km away, was scanning. The volume nearest the first event began at 01:46 UTC.
2 hail, 1 tornado, 1 debris flow, 1 thunderstorm wind. Local standard time, as filed.
Three separate Facebook posts and a Twitter post showed pictorial evidence a non-supercell tornado (landspout most likely) east of highway 395 in Lassen County.
Accumulating nickel-sized hail was reported near the Lake Davis Dam.
A CALTRANS official reported up to 4 feet of mud and debris over highway 395 near the burn scar from the Red Rock Fire (fire occurred in 2013). It took 5 hours to clear all the debris off of the road, with one car getting stuck in the debris (necessitating a rescue).
This wind gust was measured at the Bull Flat RAWS.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2015Every state in 2015This day in weather historyThe tornado archive for California, 2015Warnings in California, July 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: 583622, 594775, 594776, 594690, 594773.