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 strong thunderstorm winds.
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 strong thunderstorm winds.
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, 4 hours 32 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 257 PM MDT FRI AUG 23 2013 COZ003-007-009-232130- DEBEQUE TO SILT CORRIDOR CO-GRAND AND BATTLEMENT MESAS CO-ROAN AND TAVAPUTS PLATEAUS CO- 257 PM MDT FRI AUG 23 2013 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN GARFIELD AND EXTREME NORTHERN MESA COUNTIES UNTIL 330 PM MDT... AT 255 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR PARACHUTE...OR 33 MILES NORTHEAST OF GRAND JUNCTION...MOVING NORTHEAST AT 25 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... PARACHUTE... BATTLEMENT MESA... 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 3962 10805 3953 10779 3929 10808 3940 10827 JM
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GRAND JUNCTION CO 259 PM MDT FRI AUG 23 2013 COZ001-002-232130- CENTRAL YAMPA RIVER BASIN CO-LOWER YAMPA RIVER BASIN CO- 259 PM MDT FRI AUG 23 2013 ...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL MOFFAT COUNTY UNTIL 330 PM MDT... AT 255 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 22 MILES NORTHEAST OF RANGELY...OR 51 MILES EAST OF NAPLES...MOVING NORTHEAST AT 30 MPH. HAIL UP TO ONE-HALF INCH IN DIAMETER AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN. LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... ELK SPRINGS... 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 4061 10853 4051 10819 4024 10847 4033 10867 JM
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
302 PM MDT FRI AUG 23 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0245 PM DEBRIS FLOW 2 E RANGELY 40.09N 108.74W
08/23/2013 RIO BLANCO CO LAW ENFORCEMENT
HEAVY RAINFALL DEPOSITED MUD 6 INCHES DEEP ON HIGHWAY
64.
&&
EVENT NUMBER GJT1301398
JDCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
305 PM MDT FRI AUG 23 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0249 PM HEAVY RAIN GRAND JUNCTION 39.09N 108.55W
08/23/2013 M0.56 INCH MESA CO NWS EMPLOYEE
REPORTED FROM 8 INCH STANDARD RAIN AT NATIONAL WEATHER
OFFICE
&&
EVENT NUMBER GJT1301399
BKSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
313 PM MDT FRI AUG 23 2013
COZ004-005-232145-
ELKHEAD AND PARK MOUNTAINS CO-UPPER YAMPA RIVER BASIN CO-
313 PM MDT FRI AUG 23 2013
...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL ROUTT COUNTY UNTIL 345 PM
MDT...
AT 312 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 10 MILES NORTH OF STEAMBOAT SPRINGS...OR 36 MILES
EAST OF CRAIG...MOVING NORTHEAST AT 25 MPH.
HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN.
THIS STORM WILL BE NEAR...
CLARK AROUND 320 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 4072 10666 4069 10666 4067 10668 4064 10667
4050 10688 4058 10702 4082 10684
JMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
315 PM MDT FRI AUG 23 2013
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0207 PM TSTM WND GST 1 NNW REDLANDS 39.09N 108.66W
08/23/2013 M57 MPH MESA CO TRAINED SPOTTER
STREET FLOODING ALSO REPORTED.
&&
EVENT NUMBER GJT1301400
JDCThe Grand Junction radar (KGJX), 121 km away, was scanning. The volume nearest the first event began at 21:29 UTC.
2 flash flood, 1 thunderstorm wind. Local standard time, as filed.
A dirt road in the northwest portion of Arches National Park was closed due to mud and water approximately 1 foot deep which flowed over the roadway.
A forty-yard wide swath of water, mud and small rocks, 5 to 10 feet deep, flowed across Highway 211 near the entrance to Canyonlands National Park.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2013Every state in 2013This day in weather historyWarnings in Utah, 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: 535083, 533673, 533674.