1 lightning, as filed by the National Weather Service.
Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. 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 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 27, 1:20 PM MST, 3 hours 10 minutes earlier.
NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 220 PM MDT WED AUG 27 2003 SHORT TERM DISCUSSION: S/W TROF MOVING ENE ACRS WY WITH SRN PTN TRAILING BACK AND APCHG WRN CO ATTM. GUD PLUME OF DEEP MONSOON MSTR AHD OF SYSTEM AND TSTMS INCRSG NOW OVR THE MTNS AND FTHLS. AS THIS SYSTEM MOVES OFF THE MTNS AND ONTO THE PLAINS XPCT WLY FLOW TO BECOME ORGANIZED ENUF TO PSBLY GENERATE A LINE OF TSTMS E OF I25 THAT WILL THEN MOV ACRS PLAINS INTO THE NIGHT...AS SUGGESTED BY MM5 AND ETA MDLS. LIKELY MOST OF THE ACTION WILL SKIP OVR URBAN CORRIDOR AS SO OFTEN HAPPENS WITH THESE SYSTEMS THAT HAVE ORGANIZED WLY FLOW SO LOWER POPS W OF I25 BUT STILL THINK HIGHER POPS JUSTIFIED FARTHER E WHERE LOW LVL MSTR IS GREATER. VIS IMAGERY SGSTS LINE OF CU N/S THRU AKO MAY BE BNDRY OF THIS GREATER MSTR...THO NOT SURE HOW DEEP THIS MSTR IS SO MAX POPS WILL BE 50 PCNT. TROF AXIS WILL BE PAST FCST AREA BY 12Z WITH BIT COOLER AND QUITE A BIT DRIER AIR BHND IT SO ISOLD AT BEST FOR THU MAINLY OVR MTNS AND SRN AREAS. SZOKE LONG TERM DISCUSSION: WESTERLY FLOW ALOFT OVER AREA THROUGH FRIDAY MORNING...THEN FLOW BECOMES SOUTHWEST AS UPPER TROUGH HEADS INTO GREAT BASIN. THOUGH MODEL CROSS SECTIONS INDICATE DRIER AIR OVER AREA THURSDAY EVENING...DIV-Q FIELDS SUGGEST SOME WEAK LIFT SO CANNOT TAKE STORMS COMPLETELY OUT OF FORECAST. ON FRIDAY... SURFACE FRONT TO SLIDE SOUTH ACROSS PLAINS DURING THE MORNING AS SHORT WAVE ROTATES ACROSS AREA FROM THE SOUTHWEST. LOW LEVEL MOISTURE SHOULD INCREASE WITH UPSLOPE FLOW AND COMBINE WITH MID LEVEL MOISTURE FROM SHORTWAVE. THE ADDITION OF THE DYNAMICS WITH THE WAVE ENOUGH TO WARRANT SCATTERED POPS ACROSS CWA DURING AFTERNOON. CONVECTION COULD LAST OVERNIGHT FRIDAY...AS ETA AND AVN SUGGEST DYNAMICS CONTINUING. FOR SATURDAY...TROUGH EXPECTED TO MOVE ACROSS CWA DURING DAY...SHOULD USHER IN COOLER AIR ALONG WITH A BETTER CHANCE OF PRECIPITATION. SCATTERED POPS A GOOD PLACE TO START...STILL ALOT OF UNCERTAINTIES AS SYSTEM STILL EVOLVING IN PACIFIC NORTHWEST. THE LATEST AVN INDICATES PRECIPITATION OVER THE MOUNTAINS DURING THE MORNING HOURS...BUT HOLDS OFF ON GENERATING PRECIP ON THE PLAINS TILL THE AFTERNOON HOURS. HOWEVER...DOING SOME INTERPOLATING OF THE DIV-Q FIELDS FROM THE 60 HR ETA AT 00Z SATURDAY...THERE SHOULD BE SOME DYNAMICS ACROSS THE ENTIRE CWA THROUGHOUT THE DAY. WILL NOT GET SPECIFIC ABOUT TIMING. LATEST AVN NOT AS COLD AS PREVIOUS RUNS... BUT STILL GENERATES A COUPLE OF INCHES OF SNOW OVER MOUNTAINS BY 00Z SUNDAY. THOUGH SOME OF THE HIGHER PEAKS COULD SEE A DUSTING...WILL HOLD OFF ON MENTIONING THE SNOW WORD IN THE MOUNTAIN ZONES. LATEST AVN GUIDANCE LOOKING MORE REASONABLE... WILL MAKE SOME MINOR ADJUSTMENTS. FOR THE EXTENDED PERIOD OF SUNDAY THROUGH WEDNESDAY...THE LATEST GFS RUN CONTINUES THE TREND TOWARD DRIER AND WARMER CONDITIONS WITH UPPER LEVEL RIDGE BUILDING OVER AREA. MAY BE SOME LINGERING PRECIPITATION SUNDAY. OTHERWISE..CANNOT RULE OUT AN AFTERNOON STORM OR TWO EACH DAY AS A BIT OF MOISTURE LOOKS TO REMAIN OVER THE CWA. ON WEDNESDAY...THE MODELS SUGGEST A SHORTWAVE MOVING ACROSS THE HIGH PLAINS WHICH COULD BRING A FRONT INTO THE PLAINS AND INCREASE THE MOISTURE. THIS MAY RESULT IN A BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS WEDNESDAY AFTERNOON. WILL NEED TO LOOK AT MORE MODEL RUNS...THEN ADJUST ACCORDINGLY. D-L .DEN...NONE.
COZ030>051-281200- HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER CO 1100 AM MDT WED AUG 27 2003 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS WILL BE DEVELOPING OVER THE MOUNTAINS BY EARLY THIS AFTERNOON AND THESE ARE EXPECTED TO MOVE INTO THE URBAN CORRIDOR BY LATE AFTERNOON AND THEN ONTO THE PLAINS MAINLY THIS EVENING. STORMS ARE EXPECTED TO BE MOSTLY ISOLATED TO SCATTERED IN COVERAGE AS THEY COME INTO THE URBAN CORRIDOR WITH GUSTY WINDS POSSIBLE. FARTHER EAST LOW LEVEL MOISTURE IS HIGHER AND IT IS POSSIBLE THE STORMS WILL ORGANIZE INTO A LINE AS THEY MOVE ACROSS THE NORTHEAST PLAINS THIS EVENING...WITH GUSTY WINDS AND SOME SMALL HAIL POSSIBLE AND MAYBE BRIEF HEAVY RAIN. AT THIS TIME THE STORMS ARE EXPECTED TO REMAIN BELOW SEVERE LEVELS. AN APPROACHING UPPER LEVEL DISTURBANCE AND ASSOCIATED SURFACE TROUGH WILL BE ORGANIZING THE CONVECTION LATER TODAY AND TONIGHT. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THE TAIL END OF A WEATHER SYSTEM WILL BRUSH THE NORTHEAST PART OF THE OUTLOOK AREA THURSDAY MORNING WITH RELATIVELY QUIESCENT CONDITIONS EXPECTED IN ITS WAKE LATER THURSDAY AND INTO EARLY FRIDAY. ANOTHER WEATHER SYSTEM WILL USHER IN A ROUND OF PRECIPITATION AND COLDER TEMPERATURES LATER FRIDAY INTO SATURDAY. THIS SYSTEM MAY BE COLD ENOUGH TO BRING A FEW SNOWFLAKES TO THE HIGHEST PEAKS OVER THE WEEKEND. A GRADUAL WARMUP IS ANTICIPATED EARLY NEXT WEEK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. SZOKE/LESZCYNSKI
The Denver radar (KFTG), 64 km away, was scanning. The volume nearest the first event began at 23:30 UTC.
1 lightning. Local standard time, as filed.
Lightning struck a residence and sparked a fire in Arvada. Damage to the roof and ceiling were extensive.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2003Every state in 2003This day in weather historyWarnings in Colorado, August 2003
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: 5374739.