Thunderstorms with heavy rain caused a rock fall north that injured a hiker on the north side of the Colorado River. The heavy rain cause damage to the River Trail on the south side of the Colorado River.
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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 FGZ wrote it up.
Thunderstorms with heavy rain caused a rock fall north that injured a hiker on the north side of the Colorado River. The heavy rain cause damage to the River Trail on the south side of the Colorado River.
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 Flagstaff, AZ wrote its last area forecast discussion before the first event at Aug 3, 9:15 AM MST, 1 hour 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FLAGSTAFF AZ 915 AM MST FRI AUG 03 2012 .SYNOPSIS...AN UPPER LEVEL DISTURBANCE WILL MOVE NORTHWARD ACROSS ARIZONA AND WILL BRING AN INCREASE IN STORM ACTIVITY ACROSS THE REGION TODAY. FOR THE WEEKEND...EXPECT A CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY. && .DISCUSSION...HIGH PRESSURE REMAINS CENTERED OVER THE SOUTHERN PLAINS TODAY AND WILL CONTINUE TO BRING A MOIST SOUTHERLY FLOW ACROSS ARIZONA. A STRONG UPPER LEVEL DISTURBANCE HAS BEEN MOVING AROUND THE PERIPHERY OF THIS HIGH PRESSURE SYSTEM FOR THE PAST SEVERAL DAYS AND IS MOVING NORTHWARD ACROSS ARIZONA TODAY. THIS FEATURE WILL PROVIDE INCREASED UPWARD FORCING AS SHOWN BY DIV-Q FIELDS. GIVEN THE ALREADY PRESENT MOIST AND UNSTABLE AIR MASS THIS WILL PROBABLY RESULT IN AN INCREASE IN SHOWER AND THUNDERSTORM COVERAGE TODAY...AND THIS ACTIVITY WILL LIKELY LAST WELL INTO THE EVENING BEFORE DIMINISHING. HAVE UPDATED GRIDS FOR TODAY AND TONIGHT. FOR THE WEEKEND...THE DISTURBANCE WILL HAVE MOVED AWAY FROM THE REGION. IN ITS PLACE WILL BE A RETURN TO THE UNDISTURBED MOIST AND UNSTABLE SOUTHERLY FLOW...WITH CHANCES OF SHOWERS AND THUNDERSTORMS EACH DAY. BY EARLY NEXT WEEK...THE UPPER LEVEL HIGH MIGRATES WESTWARD AND IS CENTERED ACROSS THE FOUR CORNERS REGION. THE BEST TROPICAL MOISTURE WILL BE SHUNTED WESTWARD AND AWAY FROM AZ SO THERE WILL LIKELY BE A DOWNWARD TREND IN CONVECTIVE ACTIVITY DURING THIS PERIOD. LATE IN THE WEEK...HIGH PRESSURE RETURNS TO THE SOUTHERN PLAINS AND TROPICAL MOISTURE WILL AGAIN MOVE NORTHWARD ACROSS AZ. && .AVIATION...FOR THE 18Z PACKAGE...SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED TO DEVELOP BY 19-20Z. MVFR VISIBILITY AND GUSTY WINDS WILL BE POSSIBLE SHOULD A THUNDERSTORM AFFECT A TERMINAL. COVERAGE IS EXPECTED TO SLOWLY DECREASE AFT 02-03Z. OTHERWISE...VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && PUBLIC.........DB AVIATION.......AT FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT WEATHER.GOV/FLAGSTAFF
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE FLAGSTAFF AZ 930 AM MST FRI AUG 3 2012 AZZ004>018-037>040-040700- WESTERN MOGOLLON RIM-GRAND CANYON COUNTRY-YAVAPAI COUNTY MOUNTAINS- YAVAPAI COUNTY VALLEYS AND BASINS-OAK CREEK AND SYCAMORE CANYONS- MARBLE AND GLEN CANYONS-KAIBAB PLATEAU-COCONINO PLATEAU- NORTHEAST PLATEAU AND MESAS HWY 264 NORTHWARD- NORTHEAST PLATEAU AND MESAS SOUTH OF HWY 264- CHINLE VALLEY-CHUSKA MOUNTAINS AND DEFIANCE PLATEAU- BLACK MESA AREA-LITTLE COLORADO RIVER VALLEY IN COCONINO COUNTY- LITTLE COLORADO RIVER VALLEY IN NAVAJO COUNTY- LITTLE COLORADO RIVER VALLEY IN APACHE COUNTY- EASTERN MOGOLLON RIM-WHITE MOUNTAINS-NORTHERN GILA COUNTY- 930 AM MST FRI AUG 3 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR APACHE...COCONINO...NORTHERN GILA...NAVAJO...AND YAVAPAI COUNTIES IN NORTHERN ARIZONA. .DAY ONE...TODAY AN UPPER LEVEL DISTURBANCE WILL MOVE NORTHWARD ACROSS ARIZONA TODAY INCREASING THE CHANCES FOR SHOWERS AND THUNDERSTORMS. THE MAIN THREATS WILL BE FREQUENT LIGHTNING...SMALL HAIL...STRONG AND GUSTY WINDS...AND HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY A MOIST AND UNSTABLE AIRMASS WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND. A DOWNWARD TREND IN STORM ACTIVITY IS EXPECTED FOR THE FIRST HALF OF NEXT WEEK. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The national radar mosaic for the moment the first event began.
1 heavy rain. Local standard time, as filed.
Heavy rain from thunderstorms caused damage to the River Trail on the south side of the Colorado River about a mile from Phantom Ranch. The heavy rain also caused a rock fall that injured a 19 year old hiker in a narrow canyon about 5 miles north of Phantom Ranch.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2012Every state in 2012This day in weather historyWarnings in Arizona, August 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: 410853.