With high pressure aloft still centered in northern New Mexico, easterly flow was maintained for southeast Arizona. The atmosphere was unseasonably dry with limited moisture available.
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.
With high pressure aloft still centered in northern New Mexico, easterly flow was maintained for southeast Arizona. The atmosphere was unseasonably dry with limited moisture available. Thunderstorms that initiated near the White Mountains remained rather weak, but their outflows generated areas of blowing dust as they propagated to the southwest.
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 4, 2:40 PM MST, 2 hours 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TUCSON AZ 240 PM MST TUE AUG 4 2009 .SYNOPSIS...UPPER LEVEL HIGH PRESSURE WILL REMAIN CENTERED OVER NEW MEXICO THROUGH AT LEAST THURSDAY AFTERNOON...ALLOWING FOR FAVORABLE MONSOONAL FLOW ACROSS THE REGION. THE SOUTHEASTERLY FLOW ALOFT WILL ADVECT MOISTURE FROM NORTHERN SONORA INTO SOUTHEAST ARIZONA DURING THIS TIME FRAME...ALONG WITH WELL ABOVE NORMAL TEMPERATURES. AN UNSEASONABLY STRONG LOW PRESSURE SYSTEM OFF THE CALIFORNIA COAST WILL MOVE INLAND EARLY THURSDAY AS THE HIGH PRESSURE SYSTEM MOVES EAST. THIS WILL USHER IN NEAR NORMAL TEMPERATURES AND DRIER AIR FOR THE WEEKEND. && .DISCUSSION...THUNDERSTORMS BEGINNING TO FIRE OVER HIGHER TERRAIN OF THE EASTERN CWA. MOISTURE HOLDING A BIT BETTER THAN I WOULD HAVE THOUGHT...WITH DEWPOINTS STILL IN THE LOWER 50S MOST AREAS. THIS IS DUE TO MOISTURE ADVECTING FROM THE WESTERN DESERTS DUE TO MORNING GULF SURGE. STILL...EXPECT DEWPOINTS TO DROP INTO THE MID 40S BY LATE AFTERNOON. CONVECTION ALSO SHOWING ORGANIZATION OVER THE RIM WITH POTENTIAL RIM OUTFLOW SPREADING SOUTHWEST THIS AFTERNOON. WILL HAVE TO WATCH HOW RIM OUTFLOW INTERACTS WITH STORMS FIRING OVER HIGHER TERRAIN AREAS OF GRAHAM AND COCHISE COUNTIES. UNSEASONABLY STRONG UPPER LOW IS SEVERAL HUNDRED MILES WEST OF SAN FRANSISCO. UPPER HIGH CONTINUES ITS SLOW MIGRATION NORTHEASTWARD AND IS CURRENTLY OVER WESTERN NEW MEXICO BETWEEN GRANTS AND RESERVE. THE HIGH IS PROGGED TO SHIFT EAST ON WEDNESDAY TO A POSITION OVER EASTERN NEW MEXICO...AS INVERTED TROUGH CURRENTLY OVER EASTERN CHIHUAHUA MOVES NORTHWEST INTO NORTHERN SONORA. A RATHER COMPLICATED CONVECTIVE FORECAST TODAY. STRONG CONVECTION OVERNIGHT IN SONORA HAS PUSHED MOISTURE NORTHWARD INTO SOUTHEAST ARIZONA WITH DEWPOINTS UP 5-10 DEGREES VERSUS YESTERDAY AT THIS TIME. A SURGE OF MOISTURE HAS ALSO MOVED UP THE GULF OF CALIFORNIA AS NOTED ON YUMA OBS AND WIND PROFILE DATA...HOWEVER THIS SURGE IS RATHER SHALLOW...ONLY UP TO 3000-4000 FT MSL. THE 12Z TUS SOUNDING OFFERS SOME GOOD THINGS AND BAD THINGS FOR AFTERNOON CONVECTION. FIRST THE GOOD...MOISTURE INCREASE SHOWS PWAT VALUES NOW AROUND 1.40 INCHES...AS SUPPORTED BY GOES PWAT DATA...WITH SIGNIFICANT MOISTENING BETWEEN 12000-22000 FT. THE FLOW IS AS GOOD AS WE HAVE SEEN IN SEVERAL WEEKS WITH ABOUT 20 KTS BETWEEN 600-450 MB. THE SHEAR IS ALSO VERY GOOD WITH NORTHWEST FLOW UP TO 700 MB...EAST FROM 700-400 MB AND WEST ABOVE 300 MB WITH GOOD SPEEDS. NOW THE BAD AN UGLY INVERSION HAS DEVELOPED AROUND 450 MB AND WILL BE HARD TO OVERCOME. WHILE MOISTURE HAS INCREASED AT THE SURFACE AND AT MID-LEVELS IT IS STILL ON THE DRY SIDE BETWEEN 800-700 MB AND THIS LAYER WILL LIKELY MIX OUR SURFACE DEWPOINT INTO THE MID 40S AGAIN. THIS LEAVES VERY LITTLE CAPE FOR THE VALLEYS TO WORK WITH AND THE GULF SURGE IS PROBABLY TOO SHALLOW TO MAINTAIN LOW-LEVEL MOISTURE. EXPECT AN OVERALL INCREASE IN CONVECTION TODAY WITH BETTER ORGANIZATION...HOWEVER ACTIVITY WILL STRUGGLE OVER VALLEY LOCATIONS WITH MAIN THREAT STRONG OUTFLOW WINDS AND DUST STORM POSSIBILITIES. THE BEST ACTIVITY WILL LIKELY BE OVER SANTA CRUZ COUNTY...WHERE I ANTICIPATE THE INVERSION TO BE WEAKER AND OVER GREENLEE COUNTY...WHERE RIM OUTFLOW MAY ORGANIZE. MUCH BETTER CONVECTIVE SET UP ON WEDNESDAY AS INVERTED TROUGH PUSHES INTO NORTHERN SONORA. THIS SHOULD HELP WEAKEN INVERSION AND MOISTURE SHOULD CONTINUE INCREASING AS FLOW/SHEAR PROFILE REMAINS FAVORABLE. WILL UP POPS ON WEDNESDAY TO STANDARD MONSOON CLIMO POPS. MADE A MORNING UPDATE TO INCREASE DEWPOINTS WITH GULF SURGE AND UPPED POPS TO SCATTERED CATEGORY OVER ALL OF SANTA CRUZ COUNTY. UPPER LOW WILL PUSH ACROSS THE GREAT BASIN OVER THE WEEKEND. THIS WILL BRING A HOSTILE SOUTHWESTERLY MONSOON FLOW PATTERN BACK TO THE AREA...WITH MOISTURE LEVELS FALLING ASTONISHINGLY LOW. THE GFS PROGS PWAT VALUES BELOW 0.50...AN APRIL PATTERN IN EARLY AUGUST. WILL KEEP STORMS CONFINED TO THE FAR SOUTHEAST OVER THE WEEKEND AND THIS IS PROBABLY OPTIMISTIC. && .AVIATION...ISOLATED-SCATTERED TSRA/SHRA WILL OCCUR DURING THE 18Z-05Z PERIOD. CLOUD BASES GENERALLY 9-12K FT AGL THOUGH CEILINGS AROUND 3-5K FT AGL NEAR TSRA/SHRA. SURFACE WINDS WLY/NWLY 5-15 KTS DURING THE 18Z-05Z PERIOD. GUSTY/ERRATIC SURFACE WINDS VICINITY TSRA. WINDS BECOMING SOUTHEAST LESS THAN 10 KTS AFTER 05Z. SCT-BKN SKIES 10-15K AFTER 05Z. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...WHILE CONDITIONS REMAIN DRIER THAN WHAT IS TYPICALLY EXPECTED THIS TIME OF YEAR...RH VALUES OVER MUCH OF SOUTHEAST ARIZONA WILL STAY OVER RED FLAG THRESHOLDS. PORTIONS OF GRAHAM... SOUTHEASTERN PINAL AND NORTHERN PIMA COUNTY WILL SEE AFTERNOON MIN RH VALUES LESS THAN 15 PERCENT. WINDS WILL NOT BE AN ISSUE FOR MUCH OF THE REMAINDER OF THE WEEK. HOWEVER...A TROF OFF THE PACIFIC COAST WILL TIGHTEN GRADIENTS OVER SE AZ FOR THURSDAY INTO FRIDAY. THIS TROF WILL HAVE MINIMAL IMPACT ON RH VALUES...BUT WILL INCREASE WINDS SOMEWHAT. TO WHAT DEGREE REMAINS A QUESTION UNTIL THIS FEATURE ENTERS INTO THE REALM OF THE NEAR TERM MODELS. ONCE THIS TROF PASSES FOR THE START OF NEXT WEEK...MOISTURE IS TRENDED TO INCREASE ONCE MORE...BUT AS TO HOW THAT PERTAINS TO REEMERGENCE OF DAILY AFTERNOON AND EVENING SHOWER AND THUNDERSTORM ACTIVITY...AGAIN...IS BETTER LEFT UNANSWERED FOR NOW...ALLOWING FOR MODEL DATA TO CRYSTALLIZE AROUND A SOLUTION. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. SHOEMAKER WEATHER.GOV/TUCSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TUCSON AZ 1206 PM MST TUE AUG 4 2009 AZZ019-029>035-051915- 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- 1206 PM MST TUE AUG 4 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARIZONA AND SOUTHEAST ARIZONA. .DAY ONE...THIS AFTERNOON AND TONIGHT HIGH PRESSURE CENTERED OVER WEST CENTRAL NEW MEXICO THIS MORNING HAS RESULTED IN AN EASTERLY FLOW INTO SOUTHEAST ARIZONA. A MOIST OUTFLOW FROM CONVECTION IN SONORA MEXICO LAST EVENING PUSHED INTO THE AREA FROM THE SOUTH OVERNIGHT. ALTHOUGH THIS HAS MOISTENED UP THE LOWER LEVELS...THIS MOISTURE IS RATHER SHALLOW. IT WILL BE ENOUGH MOISTURE HOWEVER TO ALLOW ISOLATED THUNDERSTORM ACTIVITY TO DEVELOP THIS AFTERNOON AND EVENING...ESPECIALLY HIGHER TERRAIN SOUTHEAST OF TUCSON. ALTHOUGH AN INCREASING MID LEVEL EASTERLY FLOW THIS AFTERNOON SHOULD ALLOW FOR A FEW THUNDERSTORMS TO ORGANIZE INTO CLUSTERS...MOST THUNDERSTORMS WILL BE PULSE-TYPE IN NATURE. GIVEN THE FAIRLY DRY AIRMASS...THE MAIN THREAT FROM THESE STORMS TODAY WILL BE DAMAGING THUNDERSTORM WINDS AND BLOWING DUST. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY HIGH PRESSURE ALOFT WILL REMAIN CENTERED IN NEW MEXICO THROUGH THURSDAY...MAINTAINING SOUTHERLY FLOW OVER SOUTHEAST ARIZONA. THIS FLOW WILL HELP IMPORT ENOUGH MOISTURE FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS MAINLY AFTERNOON AND EVENING HOURS. AS A TROUGH OF LOW PRESSURE PUSHES THROUGH THE GREAT BASIN THURSDAY AND FRIDAY...MOISTURE WILL SHIFT EASTWARD FOR A DECREASING CHANCE OF THUNDERSTORMS AND A FEW DEGREES OF COOLING BY THIS WEEKEND. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. WEATHER.GOV/TUCSON
1 dust storm. Local standard time, as filed.
A trained spotter reported visibility less than 50 feet in blowing dust along U.S. Highway 191 south of Safford. Wind gusts of 50-55 mph were reported by ASOS and trained spotters in the Safford area.
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, August 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: 177747.