A weak upper level disturbance rotating northward out of Mexico along with abundant moisture set the stage for afternoon thunderstorms that produced winds in excess of 60 mph.
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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.
A weak upper level disturbance rotating northward out of Mexico along with abundant moisture set the stage for afternoon thunderstorms that produced winds in excess of 60 mph.
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 Jul 17, 1:25 PM MST, 2 hours 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TUCSON AZ 125 PM MST SUN JUL 17 2011 .SYNOPSIS...MOISTURE NEEDED FOR SHOWERS AND THUNDERSTORMS HAD MOVED BACK INTO THE REGION LAST NIGHT AND THIS MORNING. THIS MOISTURE RETURN WILL RESULT IN ISOLATED TO SCATTERED THUNDERSTORMS ACROSS SOUTHEAST ARIZONA EACH AFTERNOON AND EVENING THIS WEEK. A MORE SIGNIFICANT INCREASE IN MOISTURE CAN BE EXPECTED NEXT WEEKEND WITH A PRONOUNCED UPSWING IN THUNDERSTORM ACTIVITY. && .DISCUSSION...THE MOISTURE INCREASE ANTICIPATED THE PAST FEW DAYS OCCURRED LAST NIGHT AND THIS MORNING...WITH SURFACE DEWPOINTS IN THE UPPER 40S TO AROUND 60 DEGREES THIS AFTERNOON. THE 12Z UPPER-AIR SOUNDINGS AT KTWC AND KPSR BOTH SHOWED A SIGNIFICANT INCREASE IN MID-LEVEL MOISTURE WITH SATELLITE BLENDED PWATER IMAGERY SHOWING VALUES OF OVER 1 INCH ACROSS SOUTHERN ARIZONA. THIS MOISTURE IN COMBINATION WITH DAYTIME HEATING AND AN UPPER LEVEL INVERTED TROUGH APPROACHING FROM MEXICO HAD ALREADY RESULTED IN SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON. EXPECT THIS INITIAL SHOWER AND THUNDERSTORM DEVELOPMENT TO EXPAND IN COVERAGE THE REST OF THIS AFTERNOON AND THIS EVENING. A FEW SHOWERS MAY LINGER OVERNIGHT TONIGHT INTO EARLY MONDAY MORNING AS THE TROUGH PASSES THROUGH SOUTHEAST ARIZONA. THAT SAID...SHOWERS AND THUNDERSTORMS MONDAY AFTERNOON AND EVENING MIGHT BE LIMITED IN AREAL COVERAGE. THUNDERSTORM ACTIVITY TUESDAY INTO FRIDAY MAY ALSO BE SOMEWHAT LIMITED IN COVERAGE AS THE STEERING FLOW BECOMES LIGHT AND MORE WESTERLY. HOWEVER...A MORE SIGNIFICANT RETURN IN DEEP MOISTURE WAS PROGGED BY BOTH THE GFS AND ECMWF MODELS ALONG WITH A MUCH MORE FAVORABLE FLOW PATTERN/CLASSIC MONSOON PATTERN/FOR NEXT WEEKEND INTO NEXT WEEK. THEREFORE...WILL TREND RAIN CHANCES UPWARD FOR DAY 6 AND BEYOND. && .AVIATION...ISOLD-SCT -TSRA WILL CONTINUE INTO THIS EVENING ESPECIALLY EAST OF A LINE FROM CASA GRANDE-ELOY-SASABE. WINDS WILL MAINLY BE SE-SW 5-15 KTS THROUGH 17/04Z THEN GENERALLY LESS THAN 10 KTS OVERNIGHT. WINDS NEAR TSRA WILL BE GUSTY AND ERRATIC WITH GUSTS UP TO 40 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...INCREASING MOISTURE FROM THE SOUTH AND EAST WILL BRING SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS BACK TO THE AREA THIS WEEK. STRONG AND GUSTY THUNDERSTORM OUTFLOWS WILL CAUSE ERRATIC WIND CONDITIONS NEAR THUNDERSTORMS. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. WEATHER.GOV/TUCSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TUCSON AZ 955 AM MST SUN JUL 17 2011 AZZ501>515-180600- WESTERN PIMA COUNTY-TOHONO O'ODHAM NATION- UPPER SANTA CRUZ RIVER VALLEY/ALTAR VALLEY-TUCSON METRO AREA- SOUTH CENTRAL PINAL COUNTY-SOUTHEAST PINAL COUNTY- UPPER SAN PEDRO RIVER VALLEY- EASTERN COCHISE COUNTY BELOW 5000 FEET-UPPER GILA RIVER VALLEY- WHITE MOUNTAINS OF GRAHAM AND GREENLEE COUNTIES- GALIURO AND PINALENO MOUNTAINS-CHIRICAHUA MOUNTAINS- DRAGOON AND MULE AND HUACHUCA AND SANTA RITA MOUNTAINS- CATALINA AND RINCON MOUNTAINS-BABOQUIVARI MOUNTAINS- 955 AM MST SUN JUL 17 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST ARIZONA. .DAY ONE...TODAY AND TONIGHT AN INCREASE IN MOISTURE OCCURRED LAST NIGHT WHICH WILL SET THE STAGE FOR AN UPSWING IN THUNDERSTORM ACTIVITY TODAY AND TONIGHT. THIS MOISTURE IN COMBINATION WITH DAYTIME HEATING AND A WEATHER DISTURBANCE APPROACHING FROM MEXICO WILL RESULT IN ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. THE MAIN THREAT FROM THESE THUNDERSTORMS TODAY AND TONIGHT WILL BE LOCALLY STRONG WINDS IN EXCESS OF 50 MPH. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THE MOISTURE RETURN WILL RESULT IN ISOLATED TO SCATTERED THUNDERSTORMS EACH AFTERNOON AND EVENING THROUGH THE WEEK. THE MAIN THREATS FROM THUNDERSTORMS WILL BE GUSTY WINDS OVER 50 MPH...LOCALLY HEAVY RAIN...AND DANGEROUS LIGHTNING. A MORE SIGNIFICANT INCREASE IN MOISTURE AND THEREFORE THUNDERSTORM ACTIVITY WILL BE POSSIBLE OVER THE WEEKEND. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. WEATHER.GOV/TUCSON
The Tucson radar (KEMX), 41 km away, was scanning. The volume nearest the first event began at 23:01 UTC.
2 thunderstorm wind. Local standard time, as filed.
A microburst caused localized damage near 22nd and Wilmot in Tucson. A roof was peeled off a house, with part of it landing 22nd Street.
A microburst over downtown Willcox caused damage along Haskell Street. A tin roof was blown off one building while part of a roof was peeled off another. Several trees were downed including a large tree in Railroad Park.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2011Every state in 2011This day in weather historyWarnings in Arizona, July 2011
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: 329299, 329308.