An extremely moist southeast flow across Arizona brought widespread showers, thunderstorms, heavy rain, and flash flooding to northern Arizona.
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 FGZ wrote it up.
An extremely moist southeast flow across Arizona brought widespread showers, thunderstorms, heavy rain, and flash flooding to northern Arizona.
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 Jul 30, 9:45 AM MST, 1 hour 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FLAGSTAFF AZ 945 AM MST FRI JUL 30 2010 .SYNOPSIS...AN EXTREMELY MOIST SOUTHEASTERLY FLOW WILL CONTINUE TO BRING SHOWERS AND THUNDERSTORMS TO THE AREA...PRIMARILY DURING THE AFTERNOON AND EVENING HOURS. LOCALLY HEAVY RAINFALL AND THE POSSIBILITY OF FLASH FLOODING WILL CONTINUE FOR THE NEXT SEVERAL DAYS. && .DISCUSSION...A VERY MOIST AIRMASS CONTINUES TO RESIDE OVER THE AREA THIS MORNING. CURRENT OBSERVATIONS SHOW OVER 1.2 INCHES PRECIPITABLE WATER AT FLAGSTAFF...OVER 2.0 INCHES AT PHOENIX THIS MORNING. SLIGHT STABILIZATION HAS OCCURRED SINCE YESTERDAY AROUND THE 400 MB LEVEL. INSTABILITY IS NOT OVERLY IMPRESSIVE...AND THE SOUNDING SUPPORTS HEAVY RAIN WITH LIMITED LIFT IN THE PRIME HAIL GROWTH REGIONS FROM ABOUT 23-33 KFT MSL LIMITING HAIL POTENTIAL AND EXTREME MOISTURE LIMITING STRONG WIND POTENTIAL. FAIRLY EXTENSIVE CLOUD COVER OVER PORTIONS OF NORTHERN AZ SHOULD ALSO LIMIT THE INTENSITY OF CONVECTION OVER WHAT MIGHT BE EXPECTED WITH SUCH LARGE PRECIPITABLE WATER VALUES. IN SUMMARY...ANOTHER DAY OF WIDESPREAD PRECIPITATION WITH POCKETS OF VERY HEAVY RAINFALL POSSIBLE. BEST POTENTIAL FOR STRONG STORMS WILL BE IN AREAS WHICH DEVELOP A FEW HOURS OF SUNSHINE IN THE LATE MORNING/EARLY AFTERNOON. CURRENT FORECAST IS ON TRACK AND NO UPDATES PLANNED THIS MORNING. && .PREV DISCUSSION/330 AM MST/...VERY MOIST AIRMASS RESIDING OVER ARIZONA TODAY THROUGH SUNDAY...POSSIBLY LINGERING INTO MONDAY...BEFORE SLIGHTLY DRIER AIR MOVES BACK INTO THE AREA. TEMPERATURES ALOFT DO NOT SHOW ANY COOLING TREND FOR TODAY. SOME COOLING IS INDICATED FOR SATURDAY ALONG WITH SOME INCREASES IN PW VALUES. DID LOOK EXTENSIVELY AT THE DATA COMING IN FOR A POSSIBLE FFA FOR TODAY...DECIDED TO HOLD OFF SINCE THE AIRMASS ADVECTING INTO NORTHERN AZ HAS ITS ORIGINS FROM SOUTH CENTRAL PARTS OF THE STATE...THAT IS CURRENTLY EXPERIENCING ON GOING CONVECTION AS OF 10Z. IF THE DAY SHIFT WARRANTS AND THEY SEE THE CLOUD COVER CLEARING OFF EARLY...SO THAT MORE CAPE CAN BUILD UP EARLY IN THE DAY...THEN A FFA MAY BE NEEDED FOR TODAY. DID PUT INTO THE GRIDS TRW+ WITH MENTION OF HEAVY RAIN POSSIBLE TODAY THROUGH SUNDAY. FOR SATURDAY SOME COOLING ALOFT APPEARS TO OCCUR AS ADVERTISED BY THE MODELS AND WITH THE INCREASE IN MOISTURE...THOSE TWO CONDITIONS MAY BE ENOUGH TO INCREASE THE THREAT OF FLASH FLOODING...AND WARRANT AN FFA. AGAIN IF CLOUD COVER IS TOO DENSE TO BEGIN THE DAY ON SATURDAY...THAT COULD KEEP THE THREAT OF FLASH FLOODING LOW. FOR SUNDAY INTO WEDNESDAY THE LOW PRESSURE THAT MOVE WESTWARD ACROSS ARIZONA WILL CONTINUE TO MOVE FARTHER AWAY TO THE WEST ALLOWING FOR SOME MIDLEVEL DRYING...HOWEVER THE LOW LEVELS WILL STILL REMAIN FAIRLY MOIST...SO EXPECTING MORE OF A MODERATE TO PERHAPS WEAK MONSOON PATTERN SETTING UP FOR NEXT WEEK. && .AVIATION...FOR THE 18Z PACKAGE...SCT-NMRS SHRA/TSRA WILL CONTINUE INTO THE EVENING HOURS...DIMINISHING AFT 04-06Z. HEAVY RAINFALL LIKELY WITH AREAS MVFR AND LOCAL IFR VIS/CIGS PSBL. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. PUBLIC.......DJO AVIATION.....DB VISIT WEATHER.GOV/FLAGSTAFF FOR NORTHERN ARIZONA WEATHER INFORMATION.
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE FLAGSTAFF AZ 1001 AM MST FRI JUL 30 2010 AZZ004>018-037>040-310700- KAIBAB PLATEAU-MARBLE AND GLEN CANYONS-GRAND CANYON COUNTRY- COCONINO PLATEAU-YAVAPAI COUNTY MOUNTAINS- NORTHEAST PLATEAUS AND MESAS HWY 264 NORTHWARD-CHINLE VALLEY- CHUSKA MOUNTAINS AND DEFIANCE PLATEAU- LITTLE COLORADO RIVER VALLEY IN COCONINO COUNTY- LITTLE COLORADO RIVER VALLEY IN NAVAJO COUNTY- LITTLE COLORADO RIVER VALLEY IN APACHE COUNTY- WESTERN MOGOLLON RIM-EASTERN MOGOLLON RIM-WHITE MOUNTAINS- NORTHERN GILA COUNTY-YAVAPAI COUNTY VALLEYS AND BASINS- OAK CREEK AND SYCAMORE CANYONS-BLACK MESA AREA- NORTHEAST PLATEAUS AND MESAS SOUTH OF HWY 264- 1001 AM MST FRI JUL 30 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL ARIZONA...NORTH CENTRAL ARIZONA...NORTHEAST ARIZONA AND WEST CENTRAL ARIZONA. .DAY ONE...TODAY AND TONIGHT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS NORTHERN ARIZONA TODAY. STORMS ARE EXPECTED TO DEVELOP IN THE LATE MORNING IN AREAS WHICH HAVE BEEN SUNNY DURING THE MORNING...ESPECIALLY HIGH ELEVATION AREAS AND IN WESTERN COCONINO COUNTY...THEN BECOME WIDESPREAD OVER NORTHERN ARIZONA IN THE AFTERNOON AND EVENING. THE MAIN THREATS WILL BE EXTREMELY HEAVY RAIN AND LOCALIZED FLOODING. IN ADDITION...FREQUENT CLOUD-TO- GROUND LIGHTNING WILL ACCOMPANY THUNDERSTORMS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY HIGH PRESSURE EAST OF ARIZONA WILL CONTINUE TO BRING MOIST SOUTHEASTERLY FLOW OVER THE STATE. THE THREAT FOR SHOWERS AND THUNDERSTORMS ALONG WITH HEAVY RAIN WILL CONTINUE INTO EARLY NEXT WEEK WITH A POTENTIAL DRYING TREND BY MIDWEEK. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Flagstaff radar (KFSX), 121 km away, was scanning. The volume nearest the first event began at 18:16 UTC.
4 heavy rain, 3 flash flood, 1 flood. Local standard time, as filed.
A thunderstorm produced heavy rain in Prescott. A spotter reported 1.01 inches of rain in 45 minutes. Another spotter reported 0.90 inches of rain in just 20 minutes. Small streams overflowed their banks.
Weather spotters in Payson reported between 2.20 and 2.30 inches of rain. Heavy street flooding was reported with some structures threatened by over a foot of runoff.
A spotter reported 1.65 inches of rain in one hour.
Heavy rain from thunderstorms caused flash flooding in Antelope Canyon. People were stranded on ledges in this slot canyon when a four and a half foot wall of water came rushing through the canyon. Five members of a 12 member Swiss tourist group were injured. A woman and her 9 year old son sustained scrapes and busies as they were washed downstream. Three men were also injured. A second wall of water came rushing through the canyon after the people were rescued.
One inch of rain fell at Green Base Lookout Tower in 20 minutes. The storm total was 1.10 inches.
Heavy rain fell across large areas of west, central, and east Flagstaff. Rainfall rates were close to 3 inches per hour. One spotter reported 1.40 inches of rain in the first 30 minutes. Roads around town became impassible. Five cars were stalled in one intersection. Several cars became stuck in an underpass with water up to the hoods. One car started to float. It took two hours for pumps to drain the water in the underpass.
Two normally dry washes flooded. One quarter of a mile of the roadway was covered in water.
Heavy rain produced flash flooding in Sycamore Canyon. Four people became stranded near a swimming hole and had to be rescued.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2010Every state in 2010This day in weather historyWarnings in Arizona, July 2010
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: 254250, 254253, 254252, 254255, 254261, 254262, 254264, 254263.