The small levee breached along the inlet ditch for North Sterling Reservoir. Several ditches in and around Logan County Roads 39 and 41, and 34 and 36, were flooded.
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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 BOU wrote it up.
The small levee breached along the inlet ditch for North Sterling Reservoir. Several ditches in and around Logan County Roads 39 and 41, and 34 and 36, were flooded. Evacuations were also ordered.
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 May 23, 8:05 PM MST, 44 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO 905 PM MDT SAT MAY 23 2015 .UPDATE... ISSUED AT 904 PM MDT SAT MAY 23 2015 ONE LINE OF STORMS STILL MOVING ACROSS SEDGWICK AND PHILLIPS COUNTIES. SEVERE THREAT SHOULD BE LOW BUT STILL SOME POTENTIAL HEAVY RAIN. MEANWHILE WHAT SHOULD BE THE LAST LINE OF STORMS FOR THE NIGHT IS MOVING OUT OF DENVER...WITH ANOTHER PATCH OF DRY AIR BEHIND IT. WILL NEED TO HANG ON TO SOME LOW POPS THE REST OF THE NIGHT...BUT MOST OF THE SHOWER ACTIVITY SHOULD REMAIN CLOSER TO THE LOW OVER THE MOUNTAINS...AND MAINLY WEST OF OUR AREA. AREAS OF FOG DEVELOPING DUE TO CLEARING LOOKS GOOD. MAY BE ABLE TO END THE REMAINING PART OF THE FLASH FLOOD WATCH EARLY...BUT WE WILL HOLD ON TO IT FOR NOW GIVEN THAT THE STORMS IN THE CORNER ARE SLOW MOVING AND FLARING UP IN INTENSITY AGAIN AT THIS TIME. TODAYS RAIN RESULTED IN A SLIGHT UPWARD BUMP IN THE SOUTH PLATTE FLOOD FORECAST...RESULTING IN A FLOOD WARNING DOWNSTREAM AT BALZAC ON THE MORGAN/WASHINGTON COUNTY LINE. THERE WILL BE SOME RISES ON THE UPSTREAM TRIBUTARIES...FROM THE POUDRE AROUND TO THE PLATTE COMING OUT OF DENVER AND EVERYTHING IN BETWEEN...BUT THESE ARE EXPECTED TO REMAIN BELOW FLOOD STAGE. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 321 PM MDT SAT MAY 23 2015 AREAS OF THUNDERSTORMS HAVE BEEN MOVING OVER THE NORTHEAST COLORADO PLAINS FOR THE PAST COUPLE HOURS. ANOTHER STORM IS PRESENTLY MOVING OUT OF DOUGLAS COUNTY AND TRACKING NORTHEASTWARD. STORMS HAVE BEEN MOVING FAST ENOUGH THAT RAINFALL AMOUNTS HAVE GENERALLY BEEN HELD TO LESS THAN THREE-QUARTERS OF AN INCH. NO FLOODING PROBLEMS HAVE BEEN REPORTED YET...BUT WITH SOME MORE THUNDERSTORMS STILL EXPECTED...WILL LET THE FLASH FLOOD WATCH CONTINUE. THE LINEAR SHEAR PROFILE IS OVERWHELMING THE BUOYANCY OF THE AIRMASS...SO TORNADIC STORMS HAVE NOT DEVELOPED. WILL CLEAR THE WESTERN EDGE OF THE TORNADO WATCH WITH ISSUANCE OF THE AFTERNOON PACKAGE. REST OF WATCH WILL REMAIN IN PLACE SINCE THUNDERSTORM ACTIVITY IS ONGOING. AFTER THE EVENING CONVECTION DIES OFF...THE MOIST AIRMASS AND WEAK FLOW WILL ALLOW STRATUS AND FOG TO RE-DEVELOP...SIMILAR TO WHAT WE SAW THIS MORNING. FOR SUNDAY...MODELS SHOW THE UPPER LOW WILL STILL BE OVER THE CENTRAL PART OF THE STATE. THIS MEANS ANOTHER DAY OF UNSETTLED WEATHER. HAVE INCREASED THE CHANCES FOR THUNDERSTORMS TO LIKELY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 321 PM MDT SAT MAY 23 2015 SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE ACROSS NORTH CENTRAL AND NORTHEASTERN COLORADO SUNDAY EVENING AS THE UPPER LOW SLOWLY MEANDERS ACROSS THE CENTRAL ROCKIES. THE SHOWERS SHOULD GRADUALLY DECREASE ACROSS THE PLAINS AFTER MIDNIGHT WITH A CHANCE OF RAIN AND SNOW CONTINUING IN THE MOUNTAINS. ON MONDAY...THE UPPER LOW WEAKENS AND BECOMES AN OPEN TROUGH AS IT MOVES INTO THE CENTRAL PLAINS STATES. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL REDEVELOP ON THE PLAINS BY AFTERNOON AS MOISTURE ON THE BACK SIDE OF THE TROUGH WRAPS INTO COLORADO FROM THE NORTH. TEMPERATURES WILL WARM INTO THE LOWER 70S ON THE PLAINS ON TUESDAY AS UPPER LEVEL HIGH PRESSURE BUILDS OVER THE ROCKY MOUNTAIN REGION. THERE WILL STILL BE ENOUGH RESIDUAL MOISTURE AROUND...COMBINED WITH DAYTIME HEATING TO PRODUCE ISOLATED TO SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS...MOST NUMEROUS IN THE MOUNTAINS. THE UPPER FLOW BECOMES SOUTHWESTERLY ON WEDNESDAY AHEAD OF AN UPPER TROUGH OVER THE WESTERN UNITED STATES. THE SOUTHWEST FLOW WILL RESULT IN HIGH TEMPERATURES IN THE LOW 70S ON THE PLAINS WEDNESDAY AND THURSDAY. SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WILL ALSO BE POSSIBLE EACH DAY AS WEAK UPPER LEVEL DISTURBANCES INTERACT WITH RESIDUAL MOISTURE AND DAYTIME HEATING. COOLER UNSETTLED WEATHER COULD RETURN BY FRIDAY AFTERNOON AS UPSLOPE FLOW DEVELOPS BEHIND THE PASSAGE OF A COLD FRONT. THE GFS SHOWS QUITE A BIT OF QPF FROM THE CONTINENTAL DIVIDE EASTWARD INTO THE URBAN CORRIDOR SATURDAY AFTERNOON AND EVENING...WHILE THE ECMWF SHOWS VERY LITTLE. WARMER AND DRIER WEATHER IS EXPECTED BY SATURDAY AS UPPER LEVEL HIGH PRESSURE BUILDS INTO COLORADO FROM THE WEST. && .AVIATION...(FOR THE TAFS THROUGH 06Z SUNDAY EVENING) ISSUED AT 904 PM MDT SAT MAY 23 2015 THUNDERSTORMS WILL MOVE OUT OF THE DENVER AREA BY 04Z WITH CLEARING FOLLOWING. AREAS OF FOG WITH IFR CONDITIONS WILL DEVELOP BY 09Z. THERE MAY BE SOME LOCALIZED LIFR. THE FOG SHOULD BREAK UP BY 16Z. MORE THUNDERSTORMS ARE EXPECTED LATE SUNDAY AFTERNOON WITH PERIODS OF MVFR CONDITIONS AND VARIABLE GUSTY WINDS LIKELY. && .HYDROLOGY... ISSUED AT 321 PM MDT SAT MAY 23 2015 AFTERNOON THUNDERSTORMS HAVE BEEN MOVING ALONG NICELY AND ONLY PRODUCING ABOUT ONE-THIRD TO THREE-QUARTERS OF AN INCH OF RAINFALL. THE HRRR MODEL SHOWS ANOTHER ROUND OF SHOWERS OVER THE DENVER METRO AREA DURING THE EVENING...BUT WITH GENERALLY LIGHT AMOUNTS. THE THREAT OF ADDITIONAL ROUNDS OF THUNDERSTORMS ON THE NORTHEAST PLAINS CONTINUES...SO WILL LET THE FLASH FLOOD WATCH CONTINUE. THE CACHE LA POUDRE AND SOUTH PLATTE RIVERS REMAIN ABOVE FLOOD STAGE ACROSS WELD COUNTY WITH MINOR IMPACTS. THESE FLOOD WARNINGS WILL CONTINUE FOR ANOTHER COUPLE DAYS AS THE RIVERS WILL BE SLOW TO RECEDE. && .BOU WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL MIDNIGHT MDT TONIGHT FOR COZ048-050-051. && UPDATE...GIMMESTAD SHORT TERM...DANKERS LONG TERM...JK AVIATION...GIMMESTAD HYDROLOGY...DANKERS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DENVER/BOULDER CO 1111 AM MDT SAT MAY 23 2015 COZ030>051-241715- 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- 1111 AM MDT SAT MAY 23 2015 ...STRONG THUNDERSTORMS EXPECTED TO MOVE OVER NORTHEAST COLORADO THIS AFTERNOON... THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO. .DAY ONE...TODAY AND TONIGHT AN UPPER LEVEL STORM SYSTEM OVER EASTERN UTAH TODAY WILL MOVE SLOWLY INTO WESTERN COLORADO BY TONIGHT. THIS SYSTEM WILL COMBINE WITH ABUNDANT MOISTURE ACROSS EASTERN COLORADO TO PRODUCE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE AREA THIS AFTERNOON AND EARLY EVENING. A FEW SEVERE STORMS WILL BE POSSIBLE OVER THE PLAINS OF NORTHEAST COLORADO THROUGH THE AFTERNOON WITH LARGE HAIL AND A FEW TORNADOES. IN ADDITION...THUNDERSTORMS WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL WITH 1 TO 2 INCHES OF RAIN IN 30 MINUTES OR LESS. WHEN THE HEAVY RAINS DEVELOP...FLASH FLOODING WILL QUICKLY RESULT DUE TO THE SATURATED SOIL CONDITIONS. PEOPLE SHOULD REMAIN ALERT FOR RAPIDLY CHANGING CONDITIONS THROUGH THE AFTERNOON. THUNDERSTORMS WILL GENERALLY BE MOVING FROM SOUTH TO NORTH...AND MULTIPLE WAVES OF STORMS WILL BE POSSIBLE. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY SUBTLE DAY TO DAY TEMPERATURE AND PRECIPITATION CHANCES ARE IN STORE FOR THE FORECAST AREA DURING THE UPCOMING WEEK. SUNDAY AND WEDNESDAY WILL HAVE THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS WITH PASSING WEATHER SYSTEMS. MONDAY AND TUESDAY WILL BE DRIER AND WARMER WITH A PASSING HIGH PRESSURE RIDGE. ALTHOUGH DAYTIME HEATING AND RESIDUAL MOISTURE ARE LIKELY TO PRODUCE SCATTERED AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS BOTH DAYS... MAINLY OVER AND NEAR THE MOUNTAINS. BY LATE IN THE WEEK...WETTER AND COOLER CONDITIONS COULD RETURN WITH UPSLOPE FLOW AND A PASSING PACIFIC STORM SYSTEM. TEMPERATURES THROUGH THE PERIOD WILL RANGE FROM NEAR TO SLIGHTLY BELOW AVERAGE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL BE NEEDED OVER NORTHEAST COLORADO THROUGH THE AFTERNOON.
The Cheyenne radar (KCYS), 142 km away, was scanning. The volume nearest the first event began at 03:49 UTC.
1 flash flood, 1 flood. Local standard time, as filed.
The small levee breached at the inlet ditch for North Sterling Reservoir.
Heavy rain produced more flooding north of Sterling. Evacuations were ordered for Globe Meadows and areas between Globe Street and Pioneer Road due to ditch flooding west of a trailer park. Many farms in the areas reported flooded basements as well as field and roadway flooding.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2015Every state in 2015This day in weather historyWarnings in Colorado, 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: 582355, 582818.