High pressure located across southern New Mexico contributed to favorable southerly flow and abundant moisture. This combined with a mesoscale convective vortex, resulting in an active afternoon and evening of thunderstorms that produced strong winds and flash flooding, especially across western Pima County.
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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 TWC wrote it up.
High pressure located across southern New Mexico contributed to favorable southerly flow and abundant moisture. This combined with a mesoscale convective vortex, resulting in an active afternoon and evening of thunderstorms that produced strong winds and flash flooding, especially across western Pima County.
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 Tucson, AZ wrote its last area forecast discussion before the first event at Aug 17, 9:55 AM MST, 3 hours 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TUCSON AZ 955 AM MST TUE AUG 17 2010 .SYNOPSIS...A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH MIDWEEK CAN BE EXPECTED. SOME THUNDERSTORMS WILL PRODUCE HEAVY RAINFALL. THEREAFTER...THUNDERSTORM ACTIVITY WILL DECREASE SOMEWHAT LATER IN THE WEEK AS WEAK HIGH PRESSURE ALOFT REDEVELOPS OVER SOUTHERN ARIZONA. DAYTIME HIGH TEMPERATURES WILL GENERALLY AVERAGE A FEW DEGREES ABOVE NORMAL DURING THE UPCOMING WEEK. && .DISCUSSION...VERY MOIST ATMOSPHERE IN PLACE THIS MORNING ACROSS SOUTHEAST ARIZONA WITH PRECIPITABLE WATER VALUES...USING VARIOUS SOURCES...IN THE 1.70"-2" RANGE. DEBRIS CLOUDS THIS MORNING MUCH LESS THAN WHAT WAS AROUND MONDAY MORNING WITH CLEAR SKIES OVER PORTIONS OF GRAHAM/GREENLEE/SANTA CRUZ COUNTIES AND SOUTH ACROSS NORTHEAST SONORA MEXICO. ALOFT THERE IS AN INVERTED TROF EXTENDING FROM SOUTHERN ARIZONA THROUGH SONORA MEXICO WITH CENTER OF CIRCULATION JUST SOUTH OF HERMOSILLO MOVING NNW. QUESTION THIS MORNING IS...WILL THE LIFT ASSOCIATED WITH THE INVERTED TROUGH KEEP THE DEBRIS CLOUDS AROUND LONGER WHERE THEY CURRENTLY ARE AT...THUS DELAYING HEATING. HOWEVER AREAS THAT DO HAVE THE SUNSHINE WILL HEAT UP NICELY WITH STORMS DEVELOPING THIS AFTERNOON. HEAVY RAIN MAIN THREAT FROM STORMS TODAY AND ALTHOUGH THE AREA WIDE FLASH FLOOD WATCH DIDN'T WORK OUT...AND I DON'T WANT TO CRY WOLF AGAIN...MIGHT NEED ANOTHER ONE LATER THIS AFTERNOON INTO THIS EVENING...BUT WITH LESS AREAL COVERAGE. STILL GOT SOME TIME TO THINK THIS THROUGH. && .AVIATION...LEFTOVER BKN-OVC DEBRIS CLOUDINESS ABOVE 12K FT AGL WILL CONTINUE THROUGH ABOUT 18Z. THEREAFTER...SCT-BKN CLOUDS WITH BASES MAINLY 8-12K FT ARE EXPECTED THROUGH THE THE EVENING. EXPECT SCT TSRA/SHRA TO DEVELOP MAINLY AFTER 19Z TUESDAY AND CONTINUING THROUGH ABOUT 06Z WEDNESDAY. BRIEF WIND GUSTS TO 40 KTS AND MVFR CEILINGS/VSBYS ARE EXPECTED WITH THE STRONGEST STORMS. OTHERWISE...WINDS WILL BE MAINLY TERRAIN DRIVEN AND LESS THAN 10 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...NO FIRE WEATHER CONCERNS AT THIS TIME. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. WEATHER.GOV/TUCSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TUCSON AZ 1155 AM MST TUE AUG 17 2010 AZZ019-029>035-180700- NORTHERN GREENLEE COUNTY-SOUTHEAST PINAL COUNTY- UPPER GILA RIVER VALLEY-WESTERN PIMA COUNTY-TOHONO OODHAM NATION- TUCSON METRO/MARANA/GREEN VALLEY-SANTA CRUZ COUNTY-COCHISE COUNTY- 1155 AM MST TUE AUG 17 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARIZONA AND SOUTHEAST ARIZONA. .DAY ONE...THIS AFTERNOON AND TONIGHT THUNDERSTORMS WILL BE DEVELOPING THIS AFTERNOON INTO THE EARLY EVENING HOURS. SOME OF THE THUNDERSTORMS WILL BE CAPABLE OF PRODUCING HEAVY RAIN WHICH MAY LEAD TO LOCALIZED FLASH FLOODING. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THUNDERSTORMS ARE EXPECTED AGAIN WEDNESDAY WITH HEAVY RAIN AND GUSTY WINDS POSSIBLE. AFTER A DOWNTURN IN THUNDERSTORM COVERAGE TOWARD THE END OF THE WORK WEEK...AN UPTICK IN THUNDERSTORM ACTIVITY IS FORESEEN NEXT WEEKEND. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. WEATHER.GOV/TUCSON
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE TUCSON AZ 1227 PM MST TUE AUG 17 2010 AZZ031-032-172015- TOHONO OODHAM NATION AZ-WESTERN PIMA COUNTY AZ- 1227 PM MST TUE AUG 17 2010 ...SIGNIFICANT WEATHER ADVISORY FOR WESTERN PIMA COUNTY UNTIL 115 PM MST... AT 1215 PM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A CLUSTER OF STRONG THUNDERSTORMS OVER THE WESTERN TOHONO OODHAM NATION...EXTENDING FROM NORTH OF HICKIWAN TO NEAR GU VO...OR ABOUT 20 MILES EAST OF AJO...MOVING NORTHWEST AT 10 MPH. WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH VERY HEAVY RAIN OF 1 TO 2 INCHES IN A SHORT PERIOD OF TIME. AREAS AFFECTED BY THIS STORM INCLUDE...WHY...GUNSIGHT...AND KUAKATCH. THIS STORM MAY INTENSIFY. MONITOR LOCAL RADIO AND TV STATIONS...FOR ADDITIONAL INFORMATION AND POSSIBLE WARNINGS. LAT...LON 3208 11294 3251 11271 3252 11237 3199 11262 TIME...MOT...LOC 1924Z 125DEG 8KT 3235 11259 PYTLAK
The Phoenix radar (KIWA), 152 km away, was scanning. The volume nearest the first event began at 20:28 UTC.
1 thunderstorm wind, 1 flash flood. Local standard time, as filed.
A trained weather spotter measured a thunderstorm wind gust of 91 mph and law enforcement estimated wind gusts of 70 mph in town, but no damage was reported in Ajo.
A storm spotter reported that several streets in Ajo were beginning to flood as of 1:45 pm. Thereafter, at 2:47 pm a report from law enforcement stated that all roads along the Gibson Wash were barricaded due to water over the road crossings. The affected road crossings included Rasmussen Road, 22nd Avenue, and Highway 85.
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, August 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: 241957, 241949.