A moist and unstable atmosphere resulted in scattered thunderstorms developing across southeast Arizona, beginning relatively early during the midday hours. With the large amounts of moisture available, the primary threats from thunderstorms were heavy rain and flash flooding.
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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 moist and unstable atmosphere resulted in scattered thunderstorms developing across southeast Arizona, beginning relatively early during the midday hours. With the large amounts of moisture available, the primary threats from thunderstorms were heavy rain and flash flooding.
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 21, 9:50 AM MST, 2 hours 10 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TUCSON AZ 950 AM MST WED JUL 21 2010 .SYNOPSIS...AN UPSWING IN SHOWERS AND THUNDERSTORMS CAN BE EXPECTED TODAY AND THURSDAY WITH LOCALLY HEAVY RAINFALL BEING THE MAIN THREAT. OTHERWISE...PLENTY OF MOISTURE WILL REMAIN IN PLACE THE NEXT SEVERAL DAYS FOR A CHANCE OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. DAYTIME HIGH TEMPERATURES WILL BE NEAR SEASONABLE READINGS. && .DISCUSSION...SCATTERED SHOWERS AND A FEW THUNDERSTORMS CONTINUED THIS MORNING ACROSS MAINLY CENTRAL PIMA AND PINAL COUNTIES. THIS AREA OF SHOWERS AND THUNDERSTORMS APPEARED TO BE FOCUSED ALONG A WEAK DISTURBANCE TRACKING NORTHWARD THROUGH THE AREA. THE TUCSON 12Z UPPER AIR SOUNDING INDICATED A MORE UNSTABLE AIR MASS OVER THE AREA TODAY...WITH COOLER TEMPERATURES ALOFT AND A WARMER BOUNDARY LAYER COMPARED TO YESTERDAY. THE SOUNDING ALSO INDICATED A DEEPER SOUTHEASTERLY FLOW WHICH COULD RESULT IN TRAINING THUNDERSTORM CELLS TODAY. THE COMBINATION OF A FAVORABLE THERMODYNAMIC AND KINEMATIC PROFILE ALONG WITH ANOTHER DISTURBANCE TRACKING WEST OUT OF THE TEXAS BIG BEND AREA WILL INCREASE THE THREAT OF HEAVY RAINFALL TODAY. CURRENT THINKING IS THAT THE DISTURBANCE FOCUSING ACTIVITY IN CENTRAL PIMA AND PINAL COUNTIES WILL LIFT NORTHWARD WITH WEAK SUBSIDENCE SOUTH OF IT CAUSING A DIMINISH IN ACTIVITY THIS AFTERNOON THERE. THE BULK OF THE ACTIVITY IS EXPECTED TO DEVELOP ACROSS COCHISE AND SANTA CRUZ COUNTIES SOUTHWARD INTO SONORA MEXICO AS THE NEXT DISTURBANCE EXITING THE TEXAS BIG BEND AREA MOVES CLOSER. THIS ACTIVITY SHOULD TRACK/PROPAGATE NORTHWARD IMPACTING PIMA...PINAL... AND PARTS OF SOUTHERN AND WESTERN GRAHAM COUNTIES LATE THIS AFTERNOON INTO THE EVENING HOURS. ALSO EXPECTING SOME LINGER ACTIVITY OVERNIGHT TONIGHT FROM TUCSON WESTWARD. PLEASE REFER TO THE PREV DISCUSSION BELOW FOR MORE DETAILS. && .AVIATION...VALID 21/12Z-22/12Z SCT TSRA/SHRA WEST AND NW OF KTUS TO CONTINUE THRU 18Z. OTHERWISE... SCT TSRA/SHRA DEVELOPING ELSEWHERE ACROSS SE AZ AND CONTINUING INTO TONIGHT. BULK OF CONVECTIVE ACTIVITY TO END BY DAYBREAK THURSDAY. CLOUD DECKS MOSTLY 10-15K FT AGL THRU THIS PERIOD...ALTHOUGH BASES AROUND 3-6K FT AGL WITH REDUCED VSBYS VICINITY STRONGER TSTMS. SURFACE WIND THRU THURSDAY MORNING GENERALLY LESS THAN 10 KTS. HOWEVER WIND GUSTS APPROACHING 50 KTS VICINITY STRONGEST TSTMS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...NO FIRE WEATHER CONCERNS. AMPLE MOISTURE WILL BRING AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS TO SOUTHEAST ARIZONA INTO THE WEEKEND. && .PREV DISCUSSION...GFS/ECMWF CONTINUED TO BE IN FAIRLY DECENT AGREEMENT IN DEPICTING WEAK MID-LEVEL CYCLONIC CIRCULATION FEATURE TO MOVE NWD ACROSS THIS FORECAST AREA AND POTENTIALLY ENHANCING CONVECTIVE ACTIVITY ESPECIALLY DURING THE AFTERNOON AND EVENING. WILL CONTINUE TO OPT FOR HIGH-END CHANCE-CATEGORY POPS FROM TUCSON EWD WITH ISOLATED SHOWERS/TSTMS ACROSS FAR WRN PIMA COUNTY. FRIDAY...POPS TO DECREASE ABOUT 5-10 PERCENT MOST LOCALES VS THUR. SATURDAY-TUESDAY...21/00Z GFS/ECMWF WERE SIMILAR IN DEPICTING DEEP- LAYER MOISTURE TO SHIFT SOMEWHAT EWD THIS WEEKEND. POPS WILL DEPICT A SLIGHT DOWNWARD TREND TO REFLECT THESE SOLUTIONS. POPS WERE THEN TRENDED UPWARD SLIGHTLY MON-TUE AS DEEPER MOISTURE IS PROGGED TO SHIFT BACK WWD OVER SE AZ. THE UPSHOT...SCATTERED MAINLY AFTERNOON AND EVENING SHOWERS AND TSTMS EAST OF TUCSON THIS WEEKEND INTO EARLY NEXT WEEK...WITH LESSER CHANCES OF PRECIP FROM TUCSON WWD/NWWD. DAYTIME HIGH TEMPS FORECAST TO BE A FEW DEGS ABOVE NORMAL INTO EARLY NEXT WEEK. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. WEATHER.GOV/TUCSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TUCSON AZ 915 AM MST WED JUL 21 2010 AZZ029-032>035-220415- SOUTHEAST PINAL COUNTY-TOHONO OODHAM NATION- TUCSON METRO/MARANA/GREEN VALLEY-SANTA CRUZ COUNTY-COCHISE COUNTY- 915 AM MST WED JUL 21 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARIZONA AND SOUTHEAST ARIZONA. .DAY ONE...TODAY AND TONIGHT THERE IS AN INCREASED THREAT OF MORE WIDESPREAD HEAVY RAINFALL TODAY AND TONIGHT COMPARED TO THE PAST COUPLE OF DAYS. A FEW DISTURBANCES EMBEDDED IN A MODERATELY STRONG SOUTHEAST FLOW...COMBINED WITH A VERY MOIST AND UNSTABLE AIR MASS WILL RESULT IN SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TODAY. INDIVIDUAL STORM MOVEMENT WILL BE TO THE NORTH AT 15 MPH...WITH MULTIPLE STORMS PASSING OVER THE SAME AREA OFF AND ON THROUGHOUT THE DAY. LOCALLY HEAVY RAINFALL AMOUNTS ON THE ORDER TO 1 TO 2 INCHES WILL BE POSSIBLE IN SOME AREAS...ESPECIALLY IN THE MOUNTAINS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE EXPECTED AGAIN THURSDAY WITH LOCALLY RAINFALL AND STRONG WINDS BEING THE MAIN THREATS. THE GENERAL FLOW PATTERN WILL REMAIN FAVORABLE FOR SCATTERED SHOWERS AND THUNDERSTORMS THE NEXT SEVERAL DAYS. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. AZZ031-220415- WESTERN PIMA COUNTY- 915 AM MST WED JUL 21 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARIZONA. .DAY ONE...TODAY AND TONIGHT ISOLATED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED TODAY AND TONIGHT...WITH THE BULK OF THE THUNDERSTORM ACTIVITY REMAINING JUST EAST OF THE AREA ACROSS THE TOHONO OODHAM NATION. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SCATTERED THUNDERSTORMS CAN BE EXPECTED THURSDAY WITH LOCALLY RAINFALL AND STRONG WINDS BEING THE MAIN THREATS. THE GENERAL FLOW PATTERN WILL REMAIN FAVORABLE FOR SCATTERED SHOWERS AND THUNDERSTORMS THE NEXT SEVERAL DAYS. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. AZZ019-030-220415- NORTHERN GREENLEE COUNTY-UPPER GILA RIVER VALLEY- 915 AM MST WED JUL 21 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST ARIZONA. .DAY ONE...TODAY AND TONIGHT A LATER START TO SHOWER AND THUNDERSTORM DEVELOPMENT IN THE MOUNTAINS CAN BE ANTICIPATED TODAY. HOWEVER...BY LATE AFTERNOON INTO THE EVENING HOURS...SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED ACROSS MUCH OF THE AREA. THE MAIN AREA OF CONCERN WILL BE ACROSS WESTERN AND SOUTHERN GRAHAM COUNTY TODAY AND TONIGHT. A FEW OF THE STRONGER THUNDERSTORMS COULD PRODUCE LOCALLY HEAVY RAINFALL UP TO ONE INCH ALONG WITH STRONG WINDS IN EXCESS OF 50 MPH. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE EXPECTED AGAIN THURSDAY WITH LOCALLY RAINFALL AND STRONG WINDS BEING THE MAIN THREATS. THE GENERAL FLOW PATTERN WILL REMAIN FAVORABLE FOR SCATTERED SHOWERS AND THUNDERSTORMS THE NEXT SEVERAL DAYS. .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 1025 AM MST WED JUL 21 2010 AZZ034-035-211815- COCHISE COUNTY AZ-SANTA CRUZ COUNTY AZ- 1025 AM MST WED JUL 21 2010 ...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN SANTA CRUZ AND SOUTHWESTERN COCHISE COUNTIES UNTIL 1115 AM MST... AT 1018 AM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 7 MILES WEST OF SIERRA VISTA...MOVING NORTH AT 10 MPH. WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. AREAS AFFECTED BY THIS STORM INCLUDE...HUACHUCA CITY...CANELO...FORT HUACHUCA...ELGIN AND WHETSTONE. LAT...LON 3170 11062 3174 11026 3144 11028 3143 11048 TIME...MOT...LOC 1724Z 163DEG 11KT 3154 11041 CS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE TUCSON AZ 1105 AM MST WED JUL 21 2010 AZZ035-211845- COCHISE COUNTY AZ- 1105 AM MST WED JUL 21 2010 ...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN COCHISE COUNTY UNTIL 1145 AM MST... AT 1100 AM MST...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 6 MILES NORTHWEST OF BISBEE...MOVING NORTH AT 5 MPH. WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING. AREAS AFFECTED BY THIS STORM INCLUDE...MAINLY RURAL AREAS OF SOUTHERN COCHISE COUNTY. LAT...LON 3161 11011 3164 10988 3145 10985 3143 11005 TIME...MOT...LOC 1805Z 302DEG 3KT 3150 10994 CS
The Tucson radar (KEMX), 64 km away, was scanning. The volume nearest the first event began at 19:01 UTC.
3 flash flood, 1 thunderstorm wind, 1 lightning. Local standard time, as filed.
Torrential rainfall in the Huachuca Mountains led to flash flooding at the Ramsey Canyon Preserve. USGS rain gauges measured 3.82 inches of rainfall, leading to rapid rises in Ramsey Creek. Ramsey Canyon Road was closed at Calle Metate due to flooding and debris.
Severe thunderstorm winds downed three power poles on Manville Road, with one of them falling on a police vehicle. The police officer was safely extracted from the vehicle with no injuries.
Thunderstorms produced torrential rainfall on the north side of the Catalina Mountains, producing flash flooding. Rainfall estimates were locally as high as six inches in portions of southeast Pinal County, specifically near Camp Bonito. Law enforcement barricaded Mt. Lemmon and Peppersauce Roads due to flash flooding. A trained spotter measured 2.40 inches of rain 4 miles southeast of Oracle.
A pecan grove worker was struck by lightning while working near Green Valley. The man received non-life threatening injuries. A palm tree was also set ablaze by a lightning strike in the 700 block of West Rio San Pedro in Green Valley.
Law enforcement reported U.S. Highway 191 flooded near Wards Canyon and Clifton.
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: 235519, 235513, 235551, 235827, 235562.