A trough along the west coast of California pushed the subtropical high far enough eastward to allow a good push of monsoonal moisture back into the Four Corners region. The increase in thunderstorm activity seen on the 23rd led to heavy rainfall, flash flooding and isolated reports of thunderstorm wind damage.
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 GJT wrote it up.
A trough along the west coast of California pushed the subtropical high far enough eastward to allow a good push of monsoonal moisture back into the Four Corners region. The increase in thunderstorm activity seen on the 23rd led to heavy rainfall, flash flooding and isolated reports of thunderstorm wind damage.
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 23, 9:58 AM MST, 3 hours 21 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 1058 AM MDT FRI AUG 23 2013 .UPDATE... ISSUED AT 1058 AM MDT FRI AUG 23 2013 INSTABILITY GRADIENT ON NOSE OF POTENTIAL VORTICITY LOBE ROTATING AROUND THE BASE OF THE SUB TROP HIGH LEADING TO MORNING THUNDERSTORMS NORTH OF THE 4 CORNERS AREA. THIS INSTABILITY AND FORCING FOR ASCENT FROM THE PV LOBE AND DAYTIME HEATING WILL HELP SPREAD INCREASING CHANCES OF SHOWERS AND THUNDERSTORMS NORTHWARD ACROSS THE CWA THROUGH THE AFTERNOON. ADJUSTED POPS FOR CURRENT TRENDS WITH THE SOUTHERN AND CENTRAL COLORADO MOUNTAINS FAVORED FOR AFTERNOON STORMS. NORTHWEST CWA WILL ALSO BE ON THE FRINGE OF THE BETTER FORCING TO THE WEST. BETTER SHEAR AND STORM MOTION WILL ALLOW MANY STORMS TO SURVIVE AND MOVE OVER THE VALLEYS. PWAT STILL RUNNING ABOVE NORMAL SO THE THREAT OF HEAVY DOWNPOURS STILL THERE BUT FLOODING POTENTIAL SHOULD REMAIN LOCALIZED DUE TO STORM THE FASTER STORM MOTIONS TODAY. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 302 AM MDT FRI AUG 23 2013 TWO RELATIVELY WEAK DISTURBANCES ARE MOVING OVER THE CWA THIS MORNING...ONE OVER MOFFAT COUNTY STRETCHING BACK INTO RIO BLANCO AND THE EXTREME WEST END OF GARFIELD COUNTY AND THE OTHER OVER THE CENTRAL SAN JUAN MOUNTAINS. BUMPED UP POPS TO ACCOUNT FOR THIS OVERNIGHT CONVECTION. NOT MUCH CHANGE TODAY THAN SEEN PREVIOUS DAYS. FORECAST PWATS CONTINUE TO REMAIN AROUND AN INCH SO PLENTY OF MOISTURE REMAINS IN THE ATMOSPHERE. LOTS OF BKN SKIES ACROSS THE CWA EARLY THIS MORNING WILL BREAK UP SHORTLY AFTER SUNRISE SO AMPLE HEATING IS ALSO EXPECTED. SOME SHEAR DOES EXIST BETWEEN 700 TO 500MB ALBEIT ON THE LOW SIDE SO STORMS THAT DO FIRE SHOULD PERSIST A LITTLE LONGER THAN SEEN RECENTLY. EXPECT CONVECTION TO START AROUND NOON WITH STORMS FORMING AS SOON AS 1PM. SOME OF THE STORMS WILL DRIFT INTO THE VALLEYS BY MID-AFTERNOON ONWARDS. EXPECT GOOD COVERAGE OF CONVECTION TO CONTINUE THROUGH THIS EVENING WITH AMPLE MOISTURE REMAINING IN PLACE OVER THE AREA. ACTIVITY WILL WIND DOWN BY MIDNIGHT...HOWEVER EMBEDDED DISTURBANCES WILL ALLOW SOME STORMS/SHOWERS THROUGH THE NIGHT. THE DEEPEST MOISTURE WILL REMAIN ALONG OUR WESTERN EDGE SO EXPECT EASTERN UTAH MAY BE THE FAVORED AREA OVERNIGHT. ON SAT THE UPPER JET ENERGY BECOMES A LITTLE MORE PRONOUNCED BETWEEN THE SOUTHERN PLAINS HIGH AND TROUGHINESS OFF THE WEST COAST. A WEAK MAXIMA WILL BRUSH OUR NORTHWEST CORNER LATE IN THE DAY. THIS COULD PROVIDE SOME WEAK UPPER SUPPORT ENHANCING CONVECTION AND MAY ALLOW FOR SOME STRONGER STORMS. PRECIPITABLE WATER VALUES REMAIN NEAR AN INCH WITH THE DEEPEST MOISTURE ALONG OUR WESTERN EDGE. THEREFORE EXPECT SCATTERED TO NUMEROUS STORMS ACROSS THE AREA BY THE AFTERNOON. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 302 AM MDT FRI AUG 23 2013 BY SAT EVENING...MODELS SHOW A TROPICAL DISTURBANCE MOVING NORTHWARD ALONG THE WEST COAST OF THE BAJA PENINSULA THAT WILL BEGIN TO PUMP ADDITIONAL MOISTURE INTO NORTHWEST MEXICO AND AZ. THIS MOISTURE WILL REACH OUR SOUTHERN CWA SUN MORNING...THEN CONTINUE TO SPREAD NORTH THROUGH THE DAY. AGAIN THE DEEPEST MOISTURE FOR US WILL REMAIN ALONG OUR WESTERN HALF...WITH THE PLUME CENTERED ON CENTRAL UT. PRECIPITABLE WATER VALUES WILL REACH AROUND AN INCH AND A THIRD INCHES OVER SOUTHEAST UT BY THE AFTERNOON...WITH 1-1.25 INCH OVER FAR WESTERN CO AND NORTHEAST UT. EXPECT SUNDAY TO BE A CONVECTIVELY ACTIVE DAY...ESPECIALLY OVER EASTERN UT...WITH ACTIVITY INCREASING DURING THE AFTERNOON. BY SUNDAY THE SOILS IN MANY LOCATIONS WILL BE SATURATED FROM PREVIOUS DAYS' RAINS SO HEAVY RAIN WILL BE A CONCERN. THE MODELS HAVE SHOWN GOOD CONSISTENCY IN THIS SCENARIO WITH THE DEEPEST SURGE STILL TO COME. REMAINDER OF LONG-TERM LOOKS TO BE QUITE WET WITH SOME UNCERTAINTY IN FORECAST. AS DESCRIBED ABOVE...THE PLUME OF GREATEST MOISTURE IS PROGGED TO BE OVER CENTRAL UT. HOWEVER...THE EC PLACES THE HIGH PRESSURE OVER THE PLAINS JUST A LITTLE FURTHER EAST WHICH MAY ALLOW MORE MOISTURE TO FALL IN OUR CWA. FOR THE REMAINDER OF THE WEEK...THE GFS PLACES MORE PRECIP IN OUR CWA WHILE EC WANTS TO PUSH IT INTO UT. A BROAD BRUSH OF POPS OVER HIGHEST TERRAIN...FAVORING EASTERN UTAH AND AREAS SOUTH LOOKS REASONABLE WITH SOME LOW POPS IN THE VALLEYS. AN IMPORTANT NOTE...MODELS ARE HINTING AT ANOTHER TROPICAL DISTURBANCE FORMING NEAR BAJA COAST THURSDAY WITH LATER GUIDANCE SUGGESTING THIS MOISTURE WILL ALSO ADVECT NORTHWARD. NEXT WEEK WILL BE INTERESTING TO SAY THE LEAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1058 AM MDT FRI AUG 23 2013 INCREASING CLOUDINESS THIS AFTERNOON IS EXPECTED AS SHOWERS AND THUNDERSTORMS SPREAD AND MOVE NORTHWARD OVER EASTERN UTAH AND WESTERN COLORADO. THE THREAT OF A THUNDERSTORM IN THE VICINITY OF THE TERMINAL FORECAST SITES IS FAIRLY HIGH THIS AFTERNOON. THE KEGE AND KASE TERMINALS HAVE THE HIGH PROBABILITY OF SEEING SOME IMPACTS FROM THE STORMS IN THE FORM OF GUSTY OUTFLOW WINDS AND REDUCED FLIGHT CRITERIA FROM PASSING SHOWERS. AREAS OF MOUNTAIN OBSCURATION CAN ALSO BE EXPECTED THROUGH THE SUNSET. ISOLATED TO SCATTERED SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO CONTINUE ACROSS THE REGION OVERNIGHT...INCREASING IN COVERAGE ONCE AGAIN SATURDAY AFTERNOON. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && UPDATE...15 SHORT TERM...TGR/EH LONG TERM...EH/TGR AVIATION...15
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GRAND JUNCTION CO 600 AM MDT FRI AUG 23 2013 COZ001>014-017>023-UTZ022>025-027>029-241200- 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- 600 AM MDT FRI AUG 23 2013 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN UTAH AND WESTERN COLORADO. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS AND SHOWERS ARE EXPECTED TODAY...MAINLY AFTER 1PM. GUSTY WINDS UP TO 40 MPH...SMALL HAIL AND SOME HEAVY DOWNPOURS ARE POSSIBLE UNDER THE STRONGER CELLS. STORMS WILL FORM OVER THE HIGHER TERRAIN BEFORE DRIFTING INTO VALLEYS LATER IN THE DAY. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY SHOWERS AND STORMS WILL CONTINUE EACH DAY THROUGH THURSDAY. A TROPICAL DISTURBANCE IS EXPECTED TO BRING PLENTY OF MOISTURE TO EASTERN UTAH AND EXTREME WESTERN COLORADO SUNDAY INTO MONDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 130 PM MDT FRI AUG 23 2013 COZ001-UTZ024-025-232015- EASTERN UINTA BASIN UT-LOWER YAMPA RIVER BASIN CO-TAVAPUTS PLATEAU UT- 130 PM MDT FRI AUG 23 2013 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN UINTAH AND WESTERN RIO BLANCO COUNTIES UNTIL 215 PM MDT... AT 128 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 26 MILES SOUTHWEST OF RANGELY...OR 42 MILES SOUTHEAST OF NAPLES...MOVING NORTHEAST AT 25 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. THIS STORM WILL BE... SOUTHWEST OF BONANZA AROUND 150 PM MDT TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. LAT...LON 4021 10915 4009 10883 3976 10912 3984 10933 JM
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
153 PM MDT FRI AUG 23 2013
COZ006-017-232015-
GRAND VALLEY CO-UNCOMPAHGRE PLATEAU/DALLAS DIVIDE CO-
153 PM MDT FRI AUG 23 2013
...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL MESA COUNTY UNTIL 215 PM
MDT...
AT 146 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 3 MILES WEST OF GLADE PARK OR 10 MILES SOUTHWEST
OF FRUITA...MOVING NORTHEAST AT 30 MPH.
HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN.
THIS STORM WILL BE NEAR...
COLORADO NATIONAL MONUMENT AROUND 200 PM MDT.
FRUITA AND LOMA AROUND 210 PM MDT.
TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO POSSIBLE. DO NOT DRIVE YOUR VEHICLE ON A
FLOODED ROADWAY.
LAT...LON 3925 10853 3922 10849 3920 10849 3895 10873
3904 10894 3933 10873
JMSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 205 PM MDT FRI AUG 23 2013 COZ003-006-017-232030- GRAND VALLEY CO-ROAN AND TAVAPUTS PLATEAUS CO-UNCOMPAHGRE PLATEAU/DALLAS DIVIDE CO- 205 PM MDT FRI AUG 23 2013 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL MESA COUNTY UNTIL 230 PM MDT... AT 159 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 5 MILES SOUTH OF GRAND JUNCTION...MOVING NORTHEAST AT 20 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. THIS STORM WILL BE NEAR... GRAND JUNCTION AND CLIFTON AROUND 215 PM MDT. FRUITVALE AROUND 220 PM MDT. TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO POSSIBLE. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. LAT...LON 3928 10865 3923 10837 3892 10850 3896 10872 JM
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 211 PM MDT FRI AUG 23 2013 COZ001-232045- LOWER YAMPA RIVER BASIN CO- 211 PM MDT FRI AUG 23 2013 ...SIGNIFICANT WEATHER ADVISORY FOR WESTERN RIO BLANCO COUNTY UNTIL 245 PM MDT... AT 208 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 6 MILES SOUTH OF RANGELY...OR 49 MILES SOUTHEAST OF NAPLES...MOVING NORTHEAST AT 15 MPH. HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. THIS STORM WILL BE NEAR... RANGELY AROUND 225 PM MDT. TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES...IS ALSO POSSIBLE. DO NOT DRIVE YOUR VEHICLE ON A FLOODED ROADWAY. LAT...LON 4020 10879 4012 10854 3991 10873 3996 10890 JM
The Grand Junction radar (KGJX), 35 km away, was scanning. The volume nearest the first event began at 20:21 UTC.
2 thunderstorm wind, 2 flash flood, 1 debris flow. Local standard time, as filed.
Thunderstorm outflow winds blew down power poles.
Highway 64 east of Rangely was closed for a period of time when heavy rain deposited six inches of mud over the roadway.
Flash flooding closed Interstate 70 and adjacent roads near Parachute for more than two hours. An access road that runs parallel and north of I-70 was heavily damaged.
Mud and debris flowed across County Road 204, with the deepest debris field approximately 2 to 3 feet deep near mile marker 7.
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: 533667, 533671, 533668, 535076, 533670.