The trend of monthly below normal precipitation continued into the month of September across western Colorado. All climate reporting stations across the western half of the state reported readings of around a half to an inch below normal with little help from a weakening monsoonal flow.
Every event with a place to put it; 21 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 episode as NWS GJT wrote it up.
The trend of monthly below normal precipitation continued into the month of September across western Colorado. All climate reporting stations across the western half of the state reported readings of around a half to an inch below normal with little help from a weakening monsoonal flow. Little change in drought conditions were noted with severe to extreme drought levels remaining in place throughout the month. The wildland fire danger remained high during September but the main impacts were felt in the agricultural sector due to crop and pasture land losses.
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 Grand Junction, CO wrote its last area forecast discussion before the first event at Aug 31, 9:03 PM MST, 2 hours 57 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 1003 PM MDT FRI AUG 31 2012 .UPDATE... ISSUED AT 955 PM MDT FRI AUG 31 2012 CONVECTIVE SHOWERS AND THUNDERSTORMS DIMINISHING BUT ISOLATED ACTIVITY WILL PERSIST INTO LATE NIGHT...PRIMARILY EASTERN UTAH AND PERHAPS INTO THE NW COLORADO CORNER AS THE ACTIVE AREA ALONG THE UTAH/ARIZONA BORDER STREAMS NORTH NORTHEAST. HIGH RESOLUTIONS MODELS SUGGEST SW COLORADO IS FINISHED FOR THE NIGHT AND CURRENTLY CONFIRMED BY OBSERVATIONS AND HAVE SIGNIFICANTLY LOWERED GRIDDED POPS THIS AREA. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 257 PM MDT FRI AUG 31 2012 AS EXPECTED...WIDESPREAD CONVECTION HAS FORMED OVER MUCH OF EASTERN UTAH AND WESTERN COLORADO THIS AFTERNOON IN RESPONSE TO BOTH OROGRAPHIC LIFT FOR THE SAN JUANS...AND A WEAK SHORT WAVE FOR AREAS NORTH. PRECIPITABLE WATER REMAINS NEAR AN INCH ACROSS MUCH OF THE CWA SO SOME HEAVY RAIN IS STILL A CONCERN FOR THOSE STORMS TRAINING...OR REMAINING FAIRLY STATIONARY. AT THE MOMENT...SATELLITE IMAGERY SUGGESTS THE STORMS ASSOCIATED WITH THE SHORTWAVE ARE MOVING AT A GOOD CLIP...15 TO 20 MPH WHICH WILL LESSEN ANY FLOODING CONCERNS. THE STORMS AND SHOWERS OVER THE SAN JUANS HOWEVER APPEAR RELATIVELY STATIONARY AND WILL NEED TO BE MONITORED OVER THE NEXT FEW HOURS. OVERNIGHT MOST STORMS AND SHOWERS WILL DIE DOWN THOUGH THE ODD SHOWER IS NOT OUT OF THE QUESTION. ON SATURDAY...A WEAK AMPLITUDE H5 TROUGH WILL APPROACH FROM THE WEST WITH AN 85 KT JET STREAK EXITING SAID TROUGH. EARLIER RUNS HAD BEST SUPPORT OVER EASTERN UTAH/WESTERN COLORADO BUT LATEST FEW RUNS PLACE IT OVER NORTHERN AND CENTRAL UTAH. GFS/EC/NAM12 HAVE ALL TRENDED IN THIS DIRECTION AS MODELS SHOW BEST DIVERGENCE/DIV Q ALSO OVER THE SAME AREA. PWATS HAVE ALSO DROPPED TO AROUND 1 INCH THOUGH SOUTHEASTERN UTAH DOES JUMP TO ABOUT 1.1 INCHES. CONSIDERED ISSUING FLASH FLOOD WATCH AND STILL MAY BE NEEDED FOR SOUTHEASTERN UTAH BUT WITH BEST SUPPORT FURTHER WEST...WILL HOLD OFF FOR NOW. CURRENT THINKING IS ANOTHER ROUND OF SHOWERS AND CONVECTION WITH BEST FORCING TO OUR WEST WITH OROGRAPHICS PROVIDING THE NEEDED LIFT FOR CONVECTION...VERY SIMILAR TO TODAY. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 257 PM MDT FRI AUG 31 2012 THE FLOW ALOFT VEERS FROM SW TO W EARLY IN THESE PERIODS BRINGING A GENERAL DRYING TREND. DAYTIME TEMPERATURES WILL REMAIN ABOVE SEASONAL AVERAGES. SUNDAY...LIGHT SW FLOW ALOFT CONTINUES WITH MARGINAL MOISTURE ACROSS THE SOUTH AND DRIER AIR BEGINNING TO WORK OVER THE NORTH. WEAK BUT DISTINCT IMPULSES ARRIVE OFF OF THE BAJA TO PRODUCE SOME FORCING FOR STRONGER LATE-DAY STORMS. SLOW STORM MOTION STILL THREATENS SOME LOCALLY HEAVY RAINFALL SOUTH...BUT LIMITS OUTFLOW GUST POTENTIAL SOMEWHAT. MONDAY...MOISTURE CONTINUES TO ERODE OVER THE NORTHERN HALF OF THE FORECAST AREA AS THE FLOW TURNS TO WEST. MOST CONVECTION WILL BE LIMITED TO THE SOUTHERN AND CENTRAL MOUNTAINS AND SOUTHERN VALLEYS. TUESDAY-FRIDAY...MUCH DRIER AIR DOMINATES THESE PERIODS WITH ISOLATED AFTERNOON CONVECTION BEING MOSTLY LIMITED TO THE SOUTHERN MOUNTAINS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 955 PM MDT FRI AUG 31 2012 LINGERING SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH ERN UTAH AND NW COLORADO WITH GUSTY WINDS TO 30 KTS AND BRIEF -TSRA POSSIBLE. MOST ACTIVITY WILL HAVE ENDED BY 09Z...BUT THE DIURNAL CYCLE WILL BEGIN 18Z SATURDAY WITH MORE STORMS ACROSS SE UTAH AND SW COLORADO. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && UPDATE...PF SHORT TERM...TGR LONG TERM...JOE AVIATION...PF
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 527 AM MDT FRI AUG 31 2012 COZ001>014-017>023-UTZ022>025-027>029-011200- LOWER YAMPA RIVER BASIN-CENTRAL YAMPA RIVER BASIN- ROAN AND TAVAPUTS PLATEAUS-ELKHEAD AND PARK MOUNTAINS- UPPER YAMPA RIVER BASIN-GRAND VALLEY-DEBEQUE TO SILT CORRIDOR- CENTRAL COLORADO RIVER BASIN-GRAND AND BATTLEMENT MESAS- GORE AND ELK MOUNTAINS/CENTRAL MOUNTAIN VALLEYS- CENTRAL GUNNISON AND UNCOMPAHGRE RIVER BASIN- WEST ELK AND SAWATCH MOUNTAINS-FLATTOPS- UPPER GUNNISON RIVER VALLEY-UNCOMPAHGRE PLATEAU AND DALLAS DIVIDE- NORTHWEST SAN JUAN MOUNTAINS-SOUTHWEST SAN JUAN MOUNTAINS- PARADOX VALLEY/LOWER DOLORES RIVER- FOUR CORNERS/UPPER DOLORES RIVER-ANIMAS RIVER BASIN- SAN JUAN RIVER BASIN-SOUTHEAST UTAH-EASTERN UINTA MOUNTAINS- EASTERN UINTA BASIN-TAVAPUTS PLATEAU-ARCHES/GRAND FLAT- LA SAL AND ABAJO MOUNTAINS-CANYONLANDS/NATURAL BRIDGES- 527 AM MDT FRI AUG 31 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP IN THE MOUNTAINS EARLY THIS AFTERNOON. BY LATE AFTERNOON AND EVENING A FEW OF THESE STORMS WILL IMPACT VALLEY LOCATIONS. ISOLATED SHOWERS AND THUNDERSTORMS WILL PERSIST THROUGH THE NIGHT. GUSTY WINDS...BRIEF HEAVY SHOWERS AND LIGHTNING WILL BE THE PRIMARY WEATHER HAZARDS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY SATURDAY THROUGH SUNDAY...A CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE EACH DAY WITH ISOLATED SHOWERS AND THUNDERSTORMS THAT LINGER THROUGH THE NIGHT. GUSTY WINDS...BRIEF HEAVY SHOWERS AND LIGHTNING WILL REMAIN THE PRIMARY WEATHER HAZARDS. MONDAY THROUGH WEDNESDAY...MUCH DRIER WITH ISOLATED LATE DAY THUNDERSTORMS POSSIBLE OVER THE SAN JUAN MOUNTAINS IN SOUTHWEST COLORADO. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
The national radar mosaic for the moment the first event began.
21 drought. Local standard time, as filed.
Extreme drought conditions remained in place across the lower Yampa River basin through the month of September.
Extreme drought conditions remained in place across the central Yampa River basin through the month.
Extreme drought conditions remained in place across the region through the month of September.
Extreme drought conditions remained in place across the northern Park Mountains, and severe drought conditions persisted across the remainder of this zone through September.
Severe drought conditions remained constant across the upper Yampa River basin through the month of September.
Extreme drought conditions remained in place across the Grand Valley through September.
Extreme drought conditions remained in place across the central Colorado River basin through September.
Severe drought conditions remained in place across the central Colorado River basin through September.
Extreme drought conditions were eased slightly to severe conditions over the higher elevations of the Grand and Battlement Mesas in September. The lower elevations of the zone remained in extreme drought conditions through the month.
Severe drought conditions remained in place across the Gore and Elk Mountains, as well as the adjacent higher mountain valleys through September.
Severe drought conditions persisted in the southern portion of this zone through the month. Extreme drought conditions that existed across the northern portion of this zone early in the month were eased back to severe drought conditions by the end of the month.
Extreme drought conditions remained in place across the West Elk and Sawatch Mountains through September.
Severe drought conditions remained in place across the Flat Tops Mountains through September.
Extreme to severe drought conditions remained in place across the upper portions of the Gunnison River valley.
September drought conditions remained unchanged across the Uncompahgre Plateau with severe drought found across the southern portion, including the Dallas Divide area, and extreme conditions in the northern portion.
Severe drought conditions remained in place across the northwest San Juan Mountains in September.
Severe drought conditions remained in place across the southwestern San Juan Mountains in September.
Severe to extreme drought conditions remained unchanged across most of the zone through September. However, there was improvement in the southwest portion of the zone from extreme to severe drought conditions.
Extreme drought conditions in the western portion of the zone at the beginning of September improved to severe drought conditions by the end of the month. The eastern portion of the zone remained in a severe drought throughout the month.
Severe drought conditions remained in place across the Animas River basin through September.
Severe drought conditions remained in place across the San Juan River basin through September.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2012Every state in 2012This day in weather historyWarnings in Colorado, September 2012
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: 411383, 411384, 411385, 411387, 411388, 411389, 411390, 411391, 411392, 411394, 411395, 411396, 411397, 411398, 411399, 411400, 411401, 411402, 411403, 411404, 411405.