Severe thunderstorms broke out across Boulder, Denver, Elbert, Jefferson and Larimer Counties. Two large and long lived tornadoes developed in Larimer County near Berthoud and near Simla in Elbert County.
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 BOU wrote it up.
Severe thunderstorms broke out across Boulder, Denver, Elbert, Jefferson and Larimer Counties. Two large and long lived tornadoes developed in Larimer County near Berthoud and near Simla in Elbert County. The tornado that occurred along the Boulder and Larimer county line was rated an EF3 at it's highest damage point, with maximum winds estimated at 135 to 140 mph. The path length was 6 miles long with a width of one quarter mile at times. In Elbert County, 17 tornadoes touched down, with EF1 damage observed southwest and southeast of Simla. Four homes suffered severe damage; two were uninhabitable. In addition, two other homes suffered moderate damage with slight damage reported to eight other residences. Large hail up to baseball size occurred in Elbert County, with hail up to tennis ball size observed in Boulder County. The hail damaged cars and homes; breaking windows and windshields.
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 Denver/Boulder, CO wrote its last area forecast discussion before the first event at Jun 4, 8:11 AM MST, 4 hours 8 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO 911 AM MDT THU JUN 4 2015 .UPDATE... ISSUED AT 842 AM MDT THU JUN 4 2015 MAIN CONCERN AGAIN WILL BE SEVERE WEATHER POTENTIAL ACROSS THE FRONT RANGE AND NORTHEAST PLAINS. STILL DEALING WITH LOW STRATUS AND FOG ON THE PLAINS THIS AM BUT IS BEGINNING TO LIFT AND DISSIPATE OVER THE PAST HOUR OR SO. BROAD DENVER CYCLONE STILL ONGOING AND RESULTED IN A STRETCH OF STRATUS/FOG ALONG AND EAST OF THE INTERSTATE 25 CORRIDOR. THIS MAY BE A BIT SLOW TO ERODE AND WILL DELAY DISSIPATING A BIT BY LATER THIS AM. OVERALL AIRMASS HAS DRIED OVER THE FRONT RANGE IN THE PAST 12 HOURS AS WATER VAPOR SHOWING SOME DRYING AND WEAK SUBSIDENCE WITH WEAK RIDGING. APPEARS INITIAL CONVECTION WILL AGAIN BE OVER THE FOOTHILLS AND PALMER DIVIDE THIS AFTERNOON WITH BETTER HEATING. SHORT RANGE MODELS STILL FOCUSING ON STRONGER STORMS OVER DOUGLAS AND ELBERT COUNTIES WITH SOME CONVERGENCE WITH THE DENVER CYCLONE. SURFACE BASED CAPES STILL UPWARDS OF 2000J/KG WITH DEWPOINTS IN THE MID 50S TO LOWER 60S OVER THE PLAINS. OVERALL SHEAR IS WEAKER TODAY BUT STILL A LARGE HAIL THREAT UP TO 2 INCHES IN DIAMETER. GIVEN THE CONVERGENCE BOUNDARY COULD BE AN ISOLATED TORNADO AS WELL. WEAK ASCENT MOVES IN BEHIND THE RIDGING THIS EVENING SO MAYBE ABLE TO GET A BIT BETTER COVERAGE OF STORMS ON THE PLAINS THIS EVENING. STILL OVERALL COVERAGE IN THE 20-30 PERCENT RANGE OVER THE PLAINS. && .SHORT TERM...(TODAY THROUGH TONIGHT ) ISSUED AT 354 AM MDT THU JUN 4 2015 STORM INTENSITY FINALLY WEAKENED IN THE MIDNIGHT HOUR AND ALL BUT THE LAST STORMS ARE EXITING THE NORTHEAST CORNER OF THE STATE EARLY THIS MORNING. A MORE SUBSIDENT AIRMASS WILL BE OVERSPREADING THE FORECAST AREA THIS MORNING BEHIND LAST NIGHTS SHORT WAVE. THE UPPER LEVELS WILL ALSO BE DRYING AND WARMING. AS A RESULT... CONVECTIVE COVERAGE WILL TEND TO BE SUPPRESSED TODAY. HOWEVER...THE NEAR SURFACE ENVIRONMENT IS STILL JUICY ACROSS THE PLAINS AND FOOTHILLS WITH PERSISTENT EASTERLY LOW LEVEL FLOW. THAT WILL ALLOW HIGH CAPES TO DEVELOP WITH DAYTIME HEATING. SURFACE BASED CAPE VALUES SHOULD REACH 2000-3000 J/KG BUT MIXED LAYER CAPE CLOSER TO 1500-2000 J/KG AS SOME DRY AIR WILL BE JUST OFF THE DECK. WIND SHEAR WILL BE WEAKER TODAY AND GRADUALLY DECREASING THROUGH THE LATE AFTERNOON HOURS AS CONVECTION DEVELOPS...SO THREAT OF SUPERCELLS WILL BE LOWER THAN YESTERDAY. STILL EXPECT A FEW SEVERE STORMS THOUGH WITH SUCH LARGE CAPE VALUES...LARGE HAIL AND HIGH WINDS BEING THE MAIN THREATS. THERE IS A DENVER CYCLONIC CONVERGENCE ZONE ALREADY DEVELOPING...SO THIS COULD SUPPORT AN ISOLATED NON-SUPERCELL TORNADO OR TWO ALONG THIS BOUNDARY LATE THIS AFTERNOON. AT THIS TIME...LOOK FOR A FAIRLY NORMAL PLACEMENT OF THIS FEATURE BY LATE AFTERNOON FROM DOUGLAS COUNTY INTO ARAPAHOE COUNTY. THE STORMS SHOULD BECOME A BIT MORE NUMEROUS THIS EVENING AS WEAK SUBSIDENCE BEGINS TO BE REPLACED BY WEAK Q-G LIFT OVERNIGHT AHEAD OF THE NEXT SHORT WAVE. THIS WILL ALSO KEEP THE THREAT OF A FEW SHOWERS AND STORMS GOING THROUGH THE NIGHT. OTHERWISE WILL KEEP SOME PATCHY FOG IN THE FORECAST EARLY THIS MORNING WITH MOIST BOUNDARY LAYER AND PARTIAL CLEARING. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 354 AM MDT THU JUN 4 2015 MODELS KEEP SOUTHWESTERLY FLOW ALOFT FOR THE CWA FRIDAY THROUGH SATURDAY NIGHT. JET LEVEL SPEEDS ARE 30 TO 50 KNOTS. THERE IS A SUBSTANTIAL UPPER CLOSED LOW CENTERED OVER THE LOS ANGELS BASIN AT 12Z FRIDAY MORNING...WHICH ONLY MOVES TO NEAR THE SOUTHWESTERN CORNER OF UTAH BY 12Z SUNDAY MORNING. THERE IS WEAK UPWARD QG VERTICAL VELOCITY PROGGED FOR THE CWA ALL FOUR PERIODS. THE BOUNDARY LOWER FLOW WILL BE EASTERLY ON FRIDAY...THEN SOUTHEASTERLY LATER FRIDAY AFTERNOON INTO THE EVENING. NORMAL DRAINAGE KICKS IN LATER FRIDAY NIGHT...WITH SOME WEAK DOWNSLOPING ON SATURDAY...THEN MORE NORMAL DRAINAGE BY LATE EVENING. THE MODELS HAVE PLENTY OF MOISTURE FOR THE CWA FRIDAY THROUGH SATURDAY NIGHT. THERE IS A PRETTY DECENT THETA-E AXIS OVER THE PLAINS FRIDAY...AND OVER THE EASTERN TWO-THIRDS OF COLORADO ON SATURDAY. THE BOUNDARY LAYER DEW POINTS ARE IN THE 50S TO LOWER 60S F ALL FOUR PERIODS. THE CAPE VALUES OVER THE PLAINS AND FOOTHILLS ARE UP TO 3000 J/KG LATE DAY FRIDAY...AND UP TO 2500 J/KG LATE DAY SATURDAY. THERE IS FAIRLY DECENT SHEAR PROGGED LATE DAY FRIDAY ...AND EVEN BETTER LATE DAY SATURDAY. SPC HAS A BUNCH OF THE PLAINS IN A "SLIGHT RISK" OF SEVERE STORMS BOTH LATE DAY FRIDAY AND LATE DAY SATURDAY. THERE IS MEASURABLE RAINFALL OVER ALL THE CWA FRIDAY THROUGH SATURDAY NIGHT...WITH FAIRLY SIGNIFICANT AMOUNTS FRIDAY EVENING AND SATURDAY EVENING. SO FOR POPS WILL NEED TO KEEP IN OR GO-WITH "SCATTERED"S FOR THE AFTERNOON/EVENING TIMES BOTH DAYS FRIDAY AND SATURDAY. THE PRECIPITABLE WATER PROGS ARE IN THE 0.60 TO 1.30 INCH RANGE FROM THE DIVIDE THROUGH THE PLAINS ALL FOUR PERIODS...SO HEAVY RAIN IS A GOOD BET THROUGHOUT. FOR TEMPERATURES...FRIDAY'S HIGHS ARE 2-5 C COLDER THAN TODAY'S HIGHS. SATURDAY'S READINGS ARE 0-2 C WARMER THAN FRIDAY'S. FOR THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...MODELS SHOW THE UPPER CLOSED LOW TO WEAKEN AND MOVE SLOWLY EASTWARD INTO UTAH ON SUNDAY. BY MONDAY IT GETS OVER COLORADO AND IS WEAKER STILL. THE FLOW ALOFT IS PRETTY STRONG AND ZONAL ON MONDAY. THE ZONAL FLOW CONTINUES ON TUESDAY WITH UPPER RIDGING TO MOVE IN...THEN THE UPPER RIDGE IS RIGHT OVER COLORADO ON WEDNESDAY. THE AIRMASS DRIES OUT FOR MONDAY AND TUESDAY...BUT IT IS STILL FAIRLY WET SUNDAY AND MONDAY. && .AVIATION...(FOR THE TAFS THROUGH 18Z FRIDAY MORNING) ISSUED AT 842 AM MDT THU JUN 4 2015 THE DENSE FOG HAS LIFTED OVER KDEN BUT STILL SOME LOW STRATUS COVERING KDEN AND JUST ON THE EDGE AT BJC/APA DUE TO ONGOING DENVER CYCLONE. WILL CONTINUE TO SHOW SLOW IMPROVING TRENDS DURING THE MID/LATE MORNING HOURS. STILL EXPECT STRONG STORMS LATER THIS AFTERNOON WITH BEST INITIAL START NEAR APA BY 22Z. PENDING ON OUTFLOW HOW MUCH OF THIS WILL WORK INTO DEN/BJC BUT STILL ENOUGH TO MENTION STRONG STORMS IN TEMPO GROUPS. && .HYDROLOGY... ISSUED AT 354 AM MDT THU JUN 4 2015 ANY STORMS THAT DEVELOP WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL AS PRECIPITABLE WATER VALUES REMAIN NEAR 1.0 INCH ON THE PLAINS AND WARM CLOUD DEPTH NEAR 3000-4000 FEET. NOT ANTICIPATING SUFFICIENT COVERAGE AT THIS TIME TO WARRANT A FLASH FLOOD WATCH TODAY OR TONIGHT. THE THREAT OF FLASH FLOODING WILL INCREASE FRIDAY INTO THE WEEKEND AS AIRMASS BECOMES QUITE MOIST. STREAMS AND RIVERS CONTINUE TO RUN HIGH WITH SNOWMELT AND SOME RAINFALL RUNOFF. FLOOD WARNING CONTINUES FOR THE CACHE LA POUDRE AND SOUTH PLATTE IN CENTRAL WELD COUNTY...WITH ADVISORIES FOR THE CACHE LA POUDRE IN LARIMER COUNTY WHERE BIKE PATH/TRAIL FLOODING IS EXPECTED...AND SOUTH BOULDER CREEK NEAR ELDORADO SPRINGS AS FLOWS FROM GROSS RESERVOIR WILL CONTINUE TO BE ELEVATED. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && UPDATE...ENTREKIN SHORT TERM...BARJENBRUCH LONG TERM...RJK AVIATION...ENTREKIN HYDROLOGY...BARJENBRUCH
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER/BOULDER CO 1030 AM MDT THU JUN 4 2015 COZ030>051-051630- JACKSON COUNTY BELOW 9000 FEET- WEST JACKSON AND WEST GRAND COUNTIES ABOVE 9000 FEET- GRAND AND SUMMIT COUNTIES BELOW 9000 FEET- SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/ NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET- SOUTH AND SOUTHEAST GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/ GILPIN/CLEAR CREEK/SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE 9000 FEET-LARIMER AND BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET- JEFFERSON AND WEST DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR CREEK/NORTHEAST PARK COUNTIES BELOW 9000 FEET- CENTRAL AND SOUTHEAST PARK COUNTY- LARIMER COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY- BOULDER AND JEFFERSON COUNTIES BELOW 6000 FEET/WEST BROOMFIELD COUNTY- NORTH DOUGLAS COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND ARAPAHOE COUNTIES/EAST BROOMFIELD COUNTY- ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES ABOVE 6000 FEET- NORTHEAST WELD COUNTY-CENTRAL AND SOUTH WELD COUNTY-MORGAN COUNTY- CENTRAL AND EAST ADAMS AND ARAPAHOE COUNTIES- NORTH AND NORTHEAST ELBERT COUNTY BELOW 6000 FEET/NORTH LINCOLN COUNTY- SOUTHEAST ELBERT COUNTY BELOW 6000 FEET/SOUTH LINCOLN COUNTY- LOGAN COUNTY-WASHINGTON COUNTY-SEDGWICK COUNTY-PHILLIPS COUNTY- 1030 AM MDT THU JUN 4 2015 ...SEVERE STORMS POSSIBLE AGAIN TODAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT LOW LEVEL MOISTURE WILL REMAIN ENTRENCHED ACROSS THE FRONT RANGE I-25 URBAN CORRIDOR AND ADJACENT PLAINS OF COLORADO TODAY. THIS WILL KEEP A THREAT OF SEVERE THUNDERSTORMS IN THE FORECAST... ALTHOUGH THE COVERAGE OF STORMS WILL BE LESS THAN THAT OBSERVED YESTERDAY. MOST STORMS WILL PRODUCE BRIEF HEAVY RAIN...GUSTY WINDS...FREQUENT LIGHTNING...AND SMALL HAIL...BUT ISOLATED SEVERE STORMS WILL BE CAPABLE OF PRODUCING UP TO GOLF BALL SIZED HAIL AND DAMAGING WINDS. THERE IS ALSO A LOW RISK OF A BRIEF TORNADO ALONG A CONVERGENCE ZONE WHICH IS EXPECTED TO DEVELOP FROM ACROSS DOUGLAS AND ELBERT COUNTIES LATER THIS AFTERNOON. RIVERS AND STREAMS WILL CONTINUE TO RUN HIGH WITH SNOWMELT RUNOFF. MINOR FLOODING IS EXPECTED ALONG THE CACHE LA POUDRE AND SOUTH PLATTE RIVERS IN CENTRAL AND EASTERN WELD COUNTY. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY THERE WILL BE SCATTERED LATE DAY SHOWERS AND THUNDERSTORMS FRIDAY THROUGH MONDAY AS MOISTURE IS PLENTIFUL FOR THE FORECAST AREA. TUESDAY AND WEDNESDAY WILL BE A BIT WARMER WITH LESS ACTIVITY. THROUGH THE WEEKEND THE STORMS WILL BRING A RISK OF SEVERE WEATHER WITH BIG HAIL THE MAIN THREAT. HEAVY RAINFALL IS ALSO POSSIBLE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE REQUIRED AFTER 2 PM. THE MOST LIKELY LOCATION FOR SEVERE WEATHER WILL BE FROM THE PALMER DIVIDE AREA ACROSS DOUGLAS AND ELBERT COUNTIES. ENTREKIN/GIMMESTAD
The Pueblo radar (KPUX), 66 km away, was scanning. The volume nearest the first event began at 19:19 UTC.
34 hail, 18 tornado, 2 flash flood, 1 thunderstorm wind. Local standard time, as filed.
A home sustained some roof and window damage and an RV was blown on its side.
A tornado touched down briefly but did no damage.
A tornado touched down for a short time but no damage was observed.
A tornado touched down briefly but did no damage.
A well defined tornado touched down and produced some damage. Near U.S. Highway 24, tree branches 1 to 3 inches diameter were snapped. The tornado then strengthened to a magnitude EF1 tornado as it tracked south of the highway. Several hardwood trees were snapped near their trunks. A fuel tank was thrown and a barn damaged. In addition, a road sign was flattened at its base.
A tornado with an anticyclonic rotation touched down briefly but did no damage.
A tornado touched down and destroyed a pole barn.
A tornado touched down in open country. No damage was observed.
A tornado touched down in open country. No damage was observed.
A well defined tornado touched down and produced some property damage at a farmstead. The home, barn and nearby outbuildings sustained damage. A power pole was also snapped about 5 feet above the ground.
Two tornadoes touched down in close proximity to one another, one of which was anticyclonic. Both occurred in open country so no damage was observed.
A well defined tornado touched down in open country. No damage was observed.
The tornado first touched about 3 miles south of Berthoud, and then tracked to the west/northwest and lifted about 6 miles southwest of Berthoud. The majority of the damage was EF1, with some areas of EF2, and a few small areas of EF3. At least 25 homes between Longmont and Berthoud were damaged; three of them destroyed. No injuries were reported as the winds tore apart homes and rolled vehicles.
A tornado touched down in open country. No damage was observed.
A well defined tornado touched down in open country. No damage was observed.
An anticyclonic tornado touched down in open country. No damage was observed.
A tornado touched down in open country. No damage was observed.
The tornado contiinued its track into Larimer County. At least 25 homes between Longmont and Berthoud were damaged; three of them destroyed. No injuries were reported as the winds tore apart homes and rolled vehicles.
The last in a series of well defined tornadoes touched down in open country. No damage was observed.
Significant flooding was observed along the Larimer/Boulder county line. Numerous roads were closed due to flash flooding.
Heavy rain, with radar estimates up to 8 inches northwest of Longmont, forced numerous road closures. The heaviest rainfall occurred from around Lyons eastward along the Little Thompson River Basin.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2015Every state in 2015This day in weather historyThe tornado archive for Colorado, 2015Warnings in Colorado, June 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: 592024, 570428, 570429, 570430, 570431, 570432, 590625, 590626, 590627, 590628, 590632, 570439, 570447, 570446, 570438, 590634, 570437, 570436, 570435, 570445, 570434, 590636, 570433, 592087, 590642, 570444, 590647, 590651, 574167, 590652, 570443, 590654, 570455, 590658, 590659, 570452, 570459, 570442, 574168, 590664, and more.