Abundant moisture combined with a weak upper level disturbance to generate thunderstorms which produced very heavy rainfall.
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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.
Abundant moisture combined with a weak upper level disturbance to generate thunderstorms which produced very heavy rainfall.
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 21, 2:00 PM MST, 1 hour 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TUCSON AZ 200 PM MST SAT AUG 21 2010 .SYNOPSIS...A MORE FAVORABLE FLOW PATTERN FOR SHOWERS AND THUNDERSTORMS OVER SOUTHEAST ARIZONA IS EXPECTED THIS WEEKEND INTO EARLY NEXT WEEK. && .DISCUSSION...PLENTY OF DEBRIS CLOUD FROM LAST NIGHT'S STRONG COMPLEX OVER SONORA. THIS HAS INDEED HELPED DELAY CONVECTION A LITTLE TODAY AS WE INITIALLY STRUGGLED WITH SURFACE HEATING. GOES SOUNDER ESTIMATES CONFIRM THE MORNING 12Z KTUS SOUNDING WITH PLENTY OF MOISTURE AND INSTABILITY. MIGHT ALSO BE FIGHTING MODEST INHIBITION BEHIND A WEAK VORT SPOKE. WE HAVE SEEN LIMITED CLEARING ESPECIALLY NEAR THE INTERNATIONAL BORDER. WITH A CONVECTIVE TEMPERATURE IN THE MID TO UPPER 90S STILL EXPECT LATER AFTERNOON DEVELOPMENT...VALLEY AND LOWER DESERT EMPHASIS IN THE EVENING HOURS WITH ASSISTANCE FROM THE INVERTED IMPULSE NEAR THE NORTHERN GULF OF CALIFORNIA THAT HELPED FOCUS THE COMPLEX OVER SONORA LAST NIGHT. THE FLOW REMAINS FAVORABLE WITH THE HIGH CENTER JUST EAST OF THE AREA TO START THE WEEK. HIGH CENTER WOBBLING BACK OVERHEAD BY LATE TUESDAY MAY CAP SOME ACTIVITY THE SECOND HALF OF THE WEEK. && .AVIATION...ISOLD-SCT TSRA/SHRA DEVELOPING THIS AFTERNOON...THEN BECOMING MORE WIDESPREAD DURING THE MID TO LATE AFTERNOON HOURS WITH SCT-NUMEROUS TSRA/SHRA EXPECTED BETWEEN 00Z-05Z SUNDAY. OUTSIDE OF THUNDERSTORMS EXPECT SCT CLOUD BASES BETWEEN 5-7K FT AGL AND SCT-BKN CLOUD DECKS OF 10-12K FT AG...WITH A SLY/SELY SURFACE WND GENERALLY LESS THAN 12 KTS. WITH THE STRONGER STORMS...MVFR CEILINGS/VSBYS EXPECTED AND WIND GUSTS TO NEAR 45 KTS. AFT 05Z SUNDAY...THE SHOWERS AND THUNDERSTORMS WILL SLOWLY DIMINISH...ALTHOUGH A SLIGHT CHANCE OF -TSRA/SHRA WILL PERSIST THROUGH 14Z SUNDAY MORNING. EXPECT DEBRIS CLOUDINESS TO CONTINUE THROUGH THE MID MORNING HOURS ON SUNDAY AS WELL...WITH SCT-BKN CLOUDS AT 8-10K FT AGL AND BKN-OVC HIGH CIRRUS CLOUDS MAINLY ABOVE 20K FT AGL. 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 1050 AM MST SAT AUG 21 2010 AZZ019-029>035-221800- 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- 1050 AM MST SAT AUG 21 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARIZONA AND SOUTHEAST ARIZONA. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS WILL DEVELOP LATER TODAY...WITH INITIAL DEVELOPMENT ACROSS SOUTHERN AREAS BEFORE DEVELOPING LATER IN THE NORTH AND SPREADING WESTWARD THROUGH THE EVENING HOURS. EXPECT SOME STORMS TO GENERATE STRONG GUSTY WINDS AND LOCALLY HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY A CHANCE OF SHOWERS AND THUNDERSTORMS MAINLY IN AFTERNOON AND EVENING HOURS TO START THE WEEK. EXPECT GUSTY WINDS AND LOCALLY HEAVY RAINFALL WITH SOME STORMS. THE PATTERN WILL BE LESS FAVORABLE FOR STORMS LATER IN THE WEEK. .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 333 PM MST SAT AUG 21 2010 AZZ034-212315- SANTA CRUZ COUNTY AZ- 333 PM MST SAT AUG 21 2010 ...SIGNIFICANT WEATHER ADVISORY FOR EASTERN SANTA CRUZ COUNTY UNTIL 415 PM MST... AT 324 PM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR CANELO...OR ABOUT 14 MILES WEST OF SIERRA VISTA...MOVING NORTHWEST AT 10 MPH. WIND GUSTS UP TO 45 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. AREAS AFFECTED BY THIS STORM INCLUDE...SONOITA AND PATAGONIA. IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A STURDY BUILDING. LAT...LON 3148 11081 3170 11068 3158 11047 3139 11046 TIME...MOT...LOC 2232Z 137DEG 9KT 3153 11054 MEYER
The Tucson radar (KEMX), 69 km away, was scanning. The volume nearest the first event began at 22:43 UTC.
2 flash flood. Local standard time, as filed.
Very heavy rain in Nogales, Sonora caused the Nogales Wash to rise 7 feet in less than one hour. The wash rose above flood stage, causing erosion to one roadway in Nogales, Arizona.
San Simon Wash west of Pisinimo overflowed its banks, cresting at 8.3 feet, just above its 7 foot flood stage. A tributary, Gu Vo Wash, flooded Indian Road 28.
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: 244260, 243677.