Lightning injured a bicyclist in Boulder and sparked a fire in a wheat field near Deer Trail. A severe thunderstorm also produced strong winds in Arapahoe 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.
Lightning injured a bicyclist in Boulder and sparked a fire in a wheat field near Deer Trail. A severe thunderstorm also produced strong winds in Arapahoe County.
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 Aug 3, 2:27 AM MST, 9 hours 33 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 327 AM MDT MON AUG 3 2009 .SHORT TERM...CONVECTION ONGOING ACROSS MUCH OF AREA AND SEEMS TO BE ASSOCIATED WITH WEAK DISTURBANCE WHICH WATER VAPOR LOOPS SHOW MOVING ACROSS MOUNTAINS. WITH SURFACE DEWPOINTS GENERALLY IN THE 30S...STORMS PRODUCING GUSTY OUTFLOW WINDS AND MEAGER RAINFALL. SOME 40 DEGREE DEWPOINTS EAST OF A FORT MORGAN TO LIMON LINE. STORMS THAT MOVE INTO THIS REGION COULD PRODUCE BRIEF MODERATE TO HEAVY RAINFALL. NOT EXPECTING MUCH IN THE WAY OF HAIL...WITH FREEZING LEVELS AROUND 16000 FEET. SO MAIN CONCERN WILL BE THE OUTFLOW WINDS. WILL CONTINUE WITH THE ISOLATED POPS FOR THIS EVENING. MODELS SHOW WEAK SUBSIDENCE ACROSS AREA AFTER 04Z...SHOULD SEE STORMS END AT THAT TIME...WITH SKIES CLEARING. ON TUESDAY...RIDGE AXIS TO REMAIN ACROSS COLORADO AS CENTER OF RIDGE SITS OVER NEW MEXICO. LATEST NAM SHOWING LESS MOISTURE ACROSS CWA DURING THE DAY VERSUS EARLIER RUNS...MORE IN LINE WITH THE GFS. BUT BOTH MODELS INDICATE PRECIPITABLE WATER VALUES INCREASE TO OVER AN INCH ACROSS NORTHEAST CORNER. BOTH MODELS ALSO SHOW WEAK SURGE MOVING ACROSS PLAINS AROUND 17Z...WITH WEAK EASTERLY WINDS DURING THE AFTERNOON. STILL...THERE ARE STILL SOME INCONSISTENCIES BETWEEN BOTH MODELS...IN PARTICULAR THE AMOUNT OF CAPE. NAM STILL SHOWING AROUND 2000 J/KG OVER FAR NORTHEAST CORNER DURING THE AFTERNOON... WITH AROUND 1000 J/KG ALONG FRONT RANGE. GFS INDICATING MUCH LESS CAPE...RANGING FROM 100 J/KG ALONG FOOTHILLS TO AROUND 1000 J/JG NORTHEAST CORNER. WITH THIS MUCH DISCREPENCY BETWEEN THE MODELS...WILL CONTINUE WITH THE LOW POPS FOR NOW GIVEN LACK OF ANY UPPER SUPPORT TO FOCUS ON ANY ONE LOCATION. FORECAST SOUNDINGS SHOWING INVERTED-V PROFILE...SO STORMS TO PRODUCE GUSTY OUTFLOW WINDS WITH LIMITED RAINFALL. AS FOR TEMPERATURES... GUIDANCE INDICATING LITTLE AFFECT FROM THE SURGE...SHOWING TEMPERATURES SIMILAR TO TODAYS READINGS. CURRENT TEMPERATURE GRIDS IN THE LOW 90S ACROSS PLAINS...LOOKS REASONABLE. .LONG TERM...UPPER RIDGE HOLDING OVER THE SOUTHERN PLAINS THROUGH MIDWEEK...THEN THE UPSTREAM TROUGH WILL KICK NORTHEASTWARD LOWERING HEIGHS OVER COLORADO AND SHIFTING THE RIDGE AXIS EASTWARD. WEDNESDAY LOOKS THE DRIEST WITH WEAK SUBSIDENCE AND WARMING ALOFT SO CLOUD COVER SHOULD BE AT A MINIMA. RICHER LOW LEVEL MOISTURE WILL BE LINGERING OVER THE NORTHERN PLAINS AND MAY SLIDE INTO THE NORTHEAST CORNER...BUT THIS WILL LIKELY BE CAPPED. MAINTAINED LOW POPS AS STILL SOME UNCERTAINTY...WHILE FURTHER WESTWARD IT SHOULD GET HOT ENOUGH TO POP A LIMITED AMOUNT OF WEAK CONVECTION. MODELS ARE SHOWING A LITTLE MORE MOISTURE ON THURSDAY BUT MAINLY HIGH LEVELS AND COULD STILL BE MAINLY CAPPED. WEAK FRONT APPROACHING FROM THE NORTH COULD HELP THINGS ALONG LATE IN THE DAY. AS THE RIDGE SHIFTS EAST...SOUTHWEST FLOW ALOFT WILL BRING SOME OPPORTUNITY FOR MOISTURE TRANSPORT BUT IT LOOKS LIKE THIS WILL BE LIMITED. WITH CURRENT TIMING FRIDAY WOULD HAVE SOME MOISTURE ON THE TAIL OF THE TROUGH PASSING NORTH OF US...PROBABLY THE BEST CHANCE OF SHOWERS ON THIS DAY. THEN DRIER AGAIN BEHIND THIS AND SUN MAY OFFSET THE COOLING. SUBTLE MOISTENING TREND LIKELY AGAIN EARLY NEXT WEEK... BUT AT THIS POINT STILL LOOKING RELATIVELY WARM AND DRY. GRASSES WILL START TO DRY AND WE WILL SEE INCREASING FIRE DANGER...IN THE MOUNTAIN VALLEYS FIRST WHERE THE DRYING PROCESS IS ALREADY UNDER WAY. PLAINS ARE STILL GREEN AT THIS TIME. RAISED TEMPERATURES A LITTLE THROUGHOUT...GENERALLY IN LINE WITH GUIDANCE CONSENSUS. NIGHTS MAY BE NEED TO BE EVEN WARMER IN FOOTHILLS AREAS OR LATE IN THE WEEK IF THERE IS MORE CLOUD COVER. && .AVIATION...GUSTY MICROBURST WINDS TO 50 KTS POSSIBLE WITH THE ISOLATED HIGH BASED STORMS AS THEY MOVE ACROSS THE AREA. BASES OF THESE STORMS AROUND 8000-9000 FEET AGL...SO VISUAL LANDING CONDITIONS WILL CONTINUE. THE THREAT OF STORMS SHOULD END BY 04Z. VFR CONDITIONS TO PREVAIL. WEAK FRONT TO MOVE ACROSS REGION AFTER 17Z...WITH WINDS SHIFTING TO THE EAST. SLIGHT CHANCE FOR STORMS DURING THE AFTERNOON...WITH GUSTY MICROBURST WINDS TO 40 KTS THE MAIN THREAT. BASES OF THE STORMS SHOULD STAY ABOVE 6000 FEET AGL. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE. DL/CMG
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER CO 1042 AM MDT MON AUG 03 2009 COZ030>051-041200- 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- 1042 AM MDT MON AUG 03 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT ISOLATED THUNDERSTORMS WILL DEVELOP ACROSS THE AREA DURING THE AFTERNOON...CONTINUING INTO THE EVENING HOURS. THE STORMS WILL PRODUCE STRONG AND GUSTY WINDS TO 50 MPH...BUT ONLY LIGHT RAINFALL. STRONG DAYTIME HEATING WILL COMBINE WITH JUST ENOUGH MOISTURE IN THE ATMOSPHERE TO PRODUCE THE ISOLATED...HIGH BASED SHOWERS AND STORMS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY THERE IS A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS THROUGH THE WEEK. THERE IS A POSSIBILITY A FEW STORMS COULD INTENSIFY TO SEVERE STRENGTH OUT ON THE FAR NORTHEASTERN PLAINS TUESDAY AND WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. LESZCYNSKI/GIMMESTAD
The Denver radar (KFTG), 67 km away, was scanning. The volume nearest the first event began at 18:58 UTC.
2 lightning, 1 thunderstorm wind. Local standard time, as filed.
A woman riding her bike in training for an Ironman Triathalon was struck by lightning. She was in the 78th mile of a 100-mile training ride when she was hit. Initially, she lost her vision and couldn't move her arms. After a short stay in the hospital, she made a full recovery.
Lightning sparked a fire which charred approximately 1000 acres of wheat stubble.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2009Every state in 2009This day in weather historyWarnings in Colorado, August 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: 192576, 182344, 194205.