A weak surface boundary and a moist southwest flow helped focus heavy rainfall over portions of southwest Colorado. Numerous reports of heavy rainfall were received, some of which led to heavy runoff and flash flooding.
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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 GJT wrote it up.
A weak surface boundary and a moist southwest flow helped focus heavy rainfall over portions of southwest Colorado. Numerous reports of heavy rainfall were received, some of which led to heavy runoff and flash flooding.
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 8, 10:30 AM MST, 2 hours 44 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 1130 AM MDT THU AUG 8 2013 .SHORT TERM...(TODAY THROUGH FRIDAY) 343 AM MDT THU AUG 8 2013 YESTERDAYS UPPER LOW THAT HAS MOVED DOWNSTREAM LEFT BEHIND A WEAK CIRCULATION OVER THE FOUR CORNERS. CURRENTLY THIS FEATURE IS STUCK BENEATH THE HIGH PRESSURE CORE CENTERED OVER SOUTH CENTRAL WYOMING AND NW COLORADO. THE LOW CIRCULATION IS EXPECTED TO DRIFT OVER THE SAN JUAN MOUNTAINS THIS AFTERNOON AND WILL BE THE PRIMARY TRIGGER FOR WIDESPREAD SHOWERS WITH EMBEDDED STORMS. LOCALIZED MUD DEBRIS FLOWS OR ROCKSLIDES ARE POSSIBLE...BUT FORECAST QPF AMOUNTS ARE BELOW ONE HALF INCH AND BELIEVE THIS NUMBER IS TOO LOW TO WARRANT HOISTING ANOTHER FLASH FLOOD WATCH. EXPECT ISOLATED HEAVY RAINERS OVER THE SAN JUAN MOUNTAINS...MESA VERDE...LA PLATA AND ARCHULETA COUNTIES. WITH HIGHER PRESSURE TOWARD THE WYOMING BORDER...CONVECTIVE POTENTIAL BECOMES LOWER FARTHER NORTH. LEANED TOWARD THE GFS FOR TONIGHT WHICH SHIFTED THE BETTER POPS TO THE NORTH THIS EVENING WHERE IT SHOWED 700-500 MB LAYER CONVERGENCE PERSISTING PAST MIDNIGHT. EXPECT A DOWNTURN BUT NOT A COMPLETE CESSATION OF CONVECTIVE ACTIVITY ON FRIDAY. MODELS SHOW THE UPPER LOW ALONG THE WEST COAST TAKING A SHORT JAUNT INLAND OVER NRN CA ON FRI WHICH SHOULD ALLOW DRIER SW FLOW TO PUSH INTO AT LEAST ERN UT. MOS GUIDANCE SHOWS SFC DEWPOINTS DROPPING INTO THE 30S AT CORTEZ/BLANDING/MOAB FRI AFTERNOON...AND THIS APPEARS REASONABLE LOOKING UPSTREAM AT THE SFC DEWPOINTS IN NE AZ/SW UT/SRN NV. HOWEVER...EXPECT DAYTIME HEATING AND OROGRAPHICS TO STILL GENERATE SCATTERED AFTERNOON STORMS OVER THE CO MTNS WHERE MOISTURE POOLED UNDERNEATH A BUILDING RIDGE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) 343 AM MDT THU AUG 8 2013 THE UPPER LOW OVER NRN CA THEN TRACKS NORTHWARD ALONG THE OREGON COAST FRIDAY NIGHT AND SATURDAY. THIS ALLOWS FOR MORE SOUTHERLY FLOW TO RETURN WITH MODELS SHOWING MOISTURE PUSHING BACK INTO THE 4 CORNERS SATURDAY AFTERNOON. EXPECT A CONTINUATION OF ISOLATED TO SCATTERED AFTERNOON THUNDERSTORMS ON SATURDAY...FAVORING THE CENTRAL AND SOUTHWEST CO MTNS. GFS AND ECMWF INSIST ON SUPPRESSING THE MONSOONAL MOISTURE STREAM INTO THE FOUR CORNERS BY NEXT WEDNESDAY. MODEL AGREEMENT REMAINS PRETTY GOOD ON THIS OUTCOME. THE LONG WAVE TROUGH ALONG THE WEST COAST EVENTUALLY AMPLIFIES THE RIDGE AXIS OVER THE ROCKY MOUNTAIN STATES. BUT CONFIDENCE REMAINS BELOW AVERAGE WHEN THIS ACTUALLY OCCURS. THE GOING FORECAST KEEPS ISOLATED CONVECTIVE ACTIVITY OVER THE NERN HALF OF THE FORECAST AREA...WITH SCATTERED STORMS OVER SW COLORADO. THIS DAY TO DAY REPETITIVE PATTERN CONTINUES FROM SUNDAY THROUGH TUESDAY...PERHAPS TURNING DRIER NEXT WEDNESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1125 AM MDT THU AUG 8 2013 FOR SOUTHWEST COLORADO AND WEST CENTRAL COLORADO MOUNTAINS...LOCAL VIS BLO 3SM +TSRA/+SHRA WILL BRING IFR CONDITIONS TO MOUNTAIN AIRPORTS WITH PEAKS BECOMING OBSCURED THROUGH 03Z THIS EVENING. AREAL COVERAGE OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BE NUMEROUS. FOR EASTERN UTAH AND NORTHWEST COLORADO...VFR WITH ISOLATED -TSRA EXCEPT SCATTERED TSRA OVER THE MOUNTAINS FROM 20Z-03Z. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && SHORT TERM...PF/JAD LONG TERM...JAD/PF AVIATION...PF/JDC
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
The Grand Junction radar (KGJX), 198 km away, was scanning. The volume nearest the first event began at 20:14 UTC.
1 heavy rain, 1 flash flood. Local standard time, as filed.
Street flooding occurred in many areas within and near Durango. Radar estimates and CoCoRaHS reports indicated localized spots having received between 0.75 and 1.00 of an inch of rain.
Fast moving water in excess of a half-foot deep was reported to be running over County Road B25.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2013Every state in 2013This day in weather historyWarnings in Colorado, August 2013
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: 535056, 533659.