A strong ridge of high pressure was centered over the southern plains on July 10th. A shortwave trough rotating around this upper high tracked from near Chihuahua, Mexico into southeast 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 TWC wrote it up.
A strong ridge of high pressure was centered over the southern plains on July 10th. A shortwave trough rotating around this upper high tracked from near Chihuahua, Mexico into southeast Arizona. This disturbance arrived at peak heating, encouraging the development of scattered thunderstorms. With a relatively dry boundary layer, the primary threat from thunderstorms was damaging wind gusts.
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 10, 2:00 PM MST, 2 hours earlier.
AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE TUCSON AZ 200 PM MST FRI JUL 10 2009 .SYNOPSIS...HIGH PRESSURE ALOFT WILL INHIBIT WIDESPREAD THUNDERSTORM DEVELOPMENT THIS WEEKEND INTO MONDAY WHILE BRINGING HOT TEMPERATURES TO MUCH OF SOUTHERN ARIZONA. SOME LOCALES WILL APPROACH RECORD HIGH TEMPERATURES...PARTICULARLY ON SUNDAY. INCREASED MOISTURE SHOULD LEAD TO MORE SUBSTANTIAL THUNDERSTORM ACTIVITY BY MIDWEEK. && CORRECTED MOVEMENT IN SECOND PARAGRAPH. .DISCUSSION... MAIN FORECAST ISSUES CONCERN BATTLE BETWEEN HIGH PRESSURE ALOFT AND RESIDUAL MOISTURE IN AREA. MOISTURE HAS THE UPPER HAND AT THIS POINT AS THUNDERSTORMS BEGINNING TO DEVELOP OVER THE HIGH TERRAIN WITH A GENERAL SOUTHEAST TO NORTHWEST MOVEMENT. COVERAGE A LITTLE LESS THAN EXPECTED BUT SHOULD GET GOING ALONG I 19 CORRIDOR NEAR MID LEVEL MOISTURE GRADIENT AS AFTERNOON PROGRESSES. SURFACE DEWPOINT DEPRESSIONS RUNNING AT ABOUT 50 DEGREES SO CONVECTIVE WIND POTENTIAL FAIRLY HIGH ESPECIALLY IF A GIVEN CELL CAN MAINTAIN AN UPDRAFT FOR A SUBSTANTIAL PERIOD OF TIME. HEAVY RAIN THREAT A LITTLE LOWER THAN PAST FEW DAYS BUT REPEAT CELLS OR TRAINING COULD LEAD TO LOCALLY HEAVY AMOUNTS. DESPITE ONGOING STORMS...THE LOWERING OF SURFACE DEW POINTS ARE AN INDICATION THAT THE HIGH IS GAINING STRENGTH WHICH WILL ULTIMATELY RESULT IN LESS THUNDERSTORM COVERAGE OVER THE WEEKEND. THE EXTENT/DURATION OF THE CORRESPONDING WARMUP IS STILL IN QUESTION BUT SOME AREAS WILL LIKELY APPROACH RECORD HIGHS AND/OR HEAT ADVISORY CRITERIA...AT LEAST ON SUNDAY. MODELS APPEAR TO BE HOLDING ON TO THE UPPER HIGH AND DELAYING THE RETURN OF MOISTURE THROUGH AT LEAST MONDAY AND POSSIBLY TIL TUESDAY OR WEDNESDAY DEPENDING ON MODEL OF CHOICE. FOR NOW HAVE LOWERED POPS MOST SIGNIFICANTLY MONDAY THEN ONLY NUDGED SLIGHTLY LOWER TUESDAY AND HELD ON TO ESSENTIALLY CLIMO POPS WED AND BEYOND. ACCORDINGLY HAVE RAISED HIGH TEMPS A TAD EARLY IN THE WEEK. && .AVIATION...ISOLATED SHOWERS AND THUNDERSTORMS HAVE BEGUN TO DEVELOP OVER HIGHER TERRAIN EAST AND SOUTH OF KTUS. MOISTURE BOUNDARY OVER KTUS COUPLED WITH APPROACHING DISTURBANCE FROM MEXICO WILL PUT RISK FOR SHOWER AND THUNDERSTORM DEVELOPMENT IN THE MID TO LATE AFTERNOON OVER ALL 3 TERMINAL SITES. MAIN THREAT FROM THESE STORMS STRONG WINDS TO 45 KTS AND BRIEF LOCALLY HEAVY RAIN. ACTIVITY IS EXPECTED TO END BY 03Z THIS EVENING AS CLOUDS SLOWLY DISSIPATE OVERNIGHT. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...BECAUSE OF RATHER WIDESPREAD RAINS TUE AND WED...NO SIGNIFICANT FIRE WEATHER CONCERNS THROUGH SAT. HOTTER AND DRIER WEATHER EXPECTED THIS WEEKEND WITH ANY THUNDERSTORMS BECOMING ISOLATED. THAT COULD DRY FUELS ENOUGH TO RAISE FIRE CONCERNS... PARTICULARLY IN LOWER ELEVATIONS. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. KD/SR WEATHER.GOV/TUCSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TUCSON AZ 1132 AM MST FRI JUL 10 2009 AZZ019-029>035-111200- 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- 1132 AM MST FRI JUL 10 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARIZONA AND SOUTHEAST ARIZONA. .DAY ONE...THIS AFTERNOON AND TONIGHT SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP AND SPREAD NORTH ACROSS COCHISE...SANTA CRUZ AND EASTERN PIMA COUNTIES THIS AFTERNOON INTO EARLY EVENING WITH ISOLATED STORMS ALSO POSSIBLE ACROSS GRAHAM AND GREENLEE COUNTIES. THUNDERSTORM MICROBURST WINDS COULD GUST TO 50 OR 60 MPH FROM THE STRONGEST STORMS. IN ADDITION...SOME OF THE STORMS COULD PRODUCE HEAVY RAIN ON THE ORDER OF ONE INCH IN LESS THAN AN HOUR WHICH COULD LEAD TO LOCALIZED FLOODING. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THUNDERSTORM COVERAGE SHOULD DECREASE OVER THE WEEKEND BUT TEMPERATURES WILL BE HOT WITH ABOVE NORMAL TO NEAR RECORD HIGHS FORECAST. SUNDAY SHOULD BE THE HOTTEST DAY WITH TEMPERATURES RANGING FROM NEAR 100 IN THE SOUTHERN AND EASTERN VALLEYS TO THE 106 TO 113 DEGREE RANGE FROM TUCSON METRO AREA TO THE WESTERN DESERTS. NIGHTTIME LOWS WILL ALSO BE QUITE WARM AS SOME LOCALES FROM TUCSON WESTWARD REMAIN IN THE 80S OVERNIGHT. THESE TEMPERATURES MAY WARRANT HEAT ADVISORIES FOR THE LATTER HALF OF THE WEEKEND. EMERGENCY MANAGERS...HEALTH CARE OFFICIALS...AND THOSE WITH OUTDOOR PLANS SHOULD CONTINUE THEIR PREPARATIONS FOR THIS HEAT WAVE. THE HEAT MAY EASE SLIGHTLY AS THE NEW WORK WEEK UNFOLDS AND THUNDERSTORMS CHANCES INCREASE. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT DAMAGING WINDS AND FLOODING TO LOCAL LAW ENFORCEMENT OR THE NATIONAL WEATHER SERVICE. WEATHER.GOV/TUCSON
The Tucson radar (KEMX), 92 km away, was scanning. The volume nearest the first event began at 23:01 UTC.
2 thunderstorm wind, 2 lightning. Local standard time, as filed.
Law enforcement reported a ramada was blown down at the Mammoth swimming pool.
Law enforcement reported numerous tree fires started by lightning, centered near the intersection of Golf Links Road and Kolb Road.
Severe thunderstorm downburst winds blew off approximately one half of the roof of a tire shop at Golf Links Road and Kolb Road. The ceiling collapsed causing extensive damage. Downed power lines were reported near 20th and Craycroft Streets. Roof damage to a house was reported near Scarlett Street and Koralee Street. Several trees fell on cars parked at the Tucson Convention Center.
Lightning struck a tree near a restaurant parking lot, near the intersection of Wilmot Road and Tanque Verde Road. The tree caught fire and was destroyed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2009Every state in 2009This day in weather historyWarnings in Arizona, July 2009
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: 171351, 171370, 175372, 171375.