Moist southerly flow continued on August 23rd, with a high pressure ridge centered over West Texas, and a trough of low pressure over southern California. Disturbances embedded in the southerly flow enhanced thunderstorm development, resulting in both heavy rain and microburst potential.
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.
Moist southerly flow continued on August 23rd, with a high pressure ridge centered over West Texas, and a trough of low pressure over southern California. Disturbances embedded in the southerly flow enhanced thunderstorm development, resulting in both heavy rain and microburst potential.
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 23, 1:55 PM MST, 1 hour 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TUCSON AZ 155 PM MST SUN AUG 23 2009 .SYNOPSIS...A LOW PRESSURE SYSTEM NEAR NORTHERN BAJA WILL MOVE EAST TONIGHT WHILE ANOTHER DISTURBANCE APPROACHES FROM THE SOUTH. THESE SYSTEMS IN COMBINATION WITH AMPLE MOISTURE WILL LEAD TO SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. LINGERING MOISTURE FOR MORE SCATTERED SHOWERS AND THUNDERSTORMS MONDAY. DRIER AND WARMER CONDITIONS TO OCCUR DURING THE MIDDLE AND LATTER PART OF THE WEEK. && .DISCUSSION...SCATTERED SHOWERS AND THUNDERSTORMS ONGOING MAINLY ADJACENT THE HIGHER TERRAIN OF GREENLEE/GRAHAM/COCHISE COUNTIES. CELLS WERE ALSO NEAR THE SANTA RITA MOUNTAINS OF SANTA CRUZ COUNTY AS WELL AS THE CATALINA/RINCON MOUNTAINS IN ERN PIMA COUNTY. SPECIAL 18Z KTWC SOUNDING WAS SLIGHTLY DRIER VERSUS THE 12Z SOUNDING ALONG WITH VERY WEAK WIND FIELDS IN THE SURFACE-700 MB LAYER. MID-LEVEL STEERING WINDS HAD BACKED AND INCREASED SOMEWHAT VERSUS THE 12Z SOUNDING...APPARENTLY IN RESPONSE TO APPROACHING IMPULSE/VORT LOBE IN BASE OF TROUGH NEAR THE NRN/CENTRAL BAJA COAST. STILL APPEARS THAT THE PROSPECT OF SEVERE TSTMS WILL REMAIN JUST WEST OF THIS FORECAST AREA AS PER SWODY1/SWOMCD. ALTHOUGH PRECIP WATER HAS DECREASED SOMEWHAT VERSUS THE PAST 6-24 HOURS...MOISTURE IS EXPECTED TO INCREASE ACROSS SE AZ THIS EVENING AHEAD OF THE APPROACHING IMPULSE. ALSO...23/18Z NAM AND VARIOUS RUC SOLUTIONS WERE SIMILAR WITH REGARD TO DEPICTING FAIRLY DECENT RAINS ACROSS NRN SONORA THIS EVENING. THUS WILL MAINTAIN LIKELY-CATEGORY POPS FROM THE TUCSON METRO AREA EWD THIS EVENING AS WELL AS THE DEPICTION AND MENTION OF LOCALLY HEAVY RAINFALL MOST SECTIONS. PRECIP TO DIMINISH SOMEWHAT AFTER MIDNIGHT WITH THE BEST CHANCE OF MEASURABLE PRECIP EAST OF TUCSON ACROSS GREENLEE/GRAHAM/COCHISE COUNTIES. ONLY A SLIGHT CHANCE OF SHOWERS/TSTMS ACROSS FAR WRN PIMA COUNTY AFTER MIDNIGHT. CHANCE-TYPE POPS TUCSON METRO AREA LATE TONIGHT AND AGAIN MON AFTERNOON/EVENING WITH LESSER CHANCES WRN SECTIONS. DRYING TREND TO COMMENCE STARTING TUE AND SHOULD BE MOST PRONOUNCED WED-THUR AS BULK OF DEEPER MOISTURE PROGGED TO BE EAST OF THIS FORECAST AREA. MODEST MOISTURE RETURN BY THE WEEKEND AND THUS WILL DEPICT LOW-GRADE POPS FROM THE TUCSON METRO AREA EWD NEXT SAT-SUN. BELOW NORMAL DAYTIME TEMPS MON-TUE THEN WARMER WED...WITH HIGH TEMPS TRENDING ABOVE NORMAL DURING THE THUR-SUN PERIOD. && .AVIATION...SCATTERED-BROKEN CLOUDS WITH BASES GENERALLY 6-8K FT AGL ALONG WITH SCATTERED-NUMEROUS TSRA/SHRA THROUGH 24/06Z. SCATTERED TSRA/SHRA MAINLY EAST OF KTUS LATE TONIGHT AND INTO MONDAY MORNING. TSRA THRU 03Z CAPABLE OF WIND GUSTS TO 40 KTS ALONG WITH HEAVY RAIN RESULTING IN MVFR AND BRIEF IFR CONDITIONS. OTHERWISE SURFACE WINDS GENERALLY LESS THAN 10 KTS INTO MONDAY. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...NO FIRE WEATHER CONCERNS THROUGH AT LEAST TUESDAY AS AMPLE MOISTURE TO REMAIN ACROSS SOUTHEAST ARIZONA. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. BF WEATHER.GOV/TUCSON
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TUCSON AZ 335 AM MST SUN AUG 23 2009 AZZ019-029-030-033>035-240700- NORTHERN GREENLEE COUNTY-SOUTHEAST PINAL COUNTY- UPPER GILA RIVER VALLEY-TUCSON METRO/MARANA/GREEN VALLEY- SANTA CRUZ COUNTY-COCHISE COUNTY- 335 AM MST SUN AUG 23 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARIZONA AND SOUTHEAST ARIZONA. .DAY ONE...TODAY AND TONIGHT A UPPER TROUGH OF LOW PRESSURE OFF THE COAST OF NORTHERN BAJA WILL TRACK NORTHEAST TODAY INTO SOUTHERN CALIFORNIA. INITIALLY...THIS WILL RESULT IN STRONG THUNDERSTORMS OVER THE COLORADO RIVER VALLEY THIS AFTERNOON. THIS FEATURE WILL THEN ENHANCE STORM DEVELOPMENT ACROSS SOUTHEAST ARIZONA TONIGHT AND MONDAY. THE COMBINATION OF THE LIFTING MECHANISMS ASSOCIATED WITH THIS TROUGH...A MOIST AIRMASS ALREADY IN PLACE...AND A DISTURBANCE MOVING IN FROM NORTHWEST MEXICO WILL RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS TONIGHT AND MONDAY. THE MAIN THREAT FROM THESE STORMS WILL BE LOCALIZED FLASH FLOODING DUE TO WIDESPREAD HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY SOUTHEAST ARIZONA WILL CONTINUE TO RESIDE BETWEEN AN UPPER TROUGH OF LOW PRESSURE OVER SOUTHERN CALIFORNIA AND AN UPPER HIGH CENTERED OVER TEXAS MONDAY AND MONDAY NIGHT. THIS WILL CONTINUE TO PROVIDE THE AREA WITH AN ACTIVE PATTERN FOR SHOWERS AND THUNDERSTORMS. SOME STORMS WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL MONDAY INTO MONDAY EVENING. THEREAFTER...THE PATTERN BECOMES DRIER WITH SIGNIFICANTLY REDUCED CHANCES OF STORMS BY MIDWEEK. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. AZZ031-032-240700- WESTERN PIMA COUNTY-TOHONO OODHAM NATION- 335 AM MST SUN AUG 23 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL ARIZONA. .DAY ONE...TODAY AND TONIGHT A UPPER TROUGH OF LOW PRESSURE OFF THE COAST OF NORTHERN BAJA WILL TRACK NORTHEAST TODAY INTO SOUTHERN CALIFORNIA. INITIALLY...THIS WILL RESULT IN STRONG THUNDERSTORMS OVER THE COLORADO RIVER VALLEY THIS AFTERNOON. THESE STORMS WILL TRACK INTO CENTRAL AND WESTERN PIMA COUNTY LATE THIS AFTERNOON INTO THE EARLY EVENING. THE MAIN THREAT FROM THESE STORMS WILL BE DAMAGING THUNDERSTORM OUTFLOW WINDS. THIS TROUGH WILL THEN ENHANCE STORM DEVELOPMENT ACROSS SOUTHEAST ARIZONA TONIGHT AND MONDAY. THE COMBINATION OF THE LIFTING MECHANISMS ASSOCIATED WITH THIS TROUGH...A MOIST AIRMASS ALREADY IN PLACE...AND A DISTURBANCE MOVING IN FROM NORTHWEST MEXICO WILL RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS TONIGHT AND MONDAY. THE MAIN THREAT FROM THESE STORMS WILL BE LOCALIZED FLASH FLOODING DUE TO WIDESPREAD HEAVY RAINFALL. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY SOUTHEAST ARIZONA WILL CONTINUE TO RESIDE BETWEEN AN UPPER TROUGH OF LOW PRESSURE OVER SOUTHERN CALIFORNIA AND AN UPPER HIGH CENTERED OVER TEXAS MONDAY AND MONDAY NIGHT. THIS WILL CONTINUE TO PROVIDE THE AREA WITH AN ACTIVE PATTERN FOR SHOWERS AND THUNDERSTORMS. SOME STORMS WILL BE CAPABLE OF PRODUCING HEAVY RAINFALL MONDAY INTO MONDAY EVENING. THEREAFTER...THE PATTERN BECOMES DRIER WITH SIGNIFICANTLY REDUCED CHANCES OF STORMS BY MIDWEEK. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. WEATHER.GOV/TUCSON
The Tucson radar (KEMX), 21 km away, was scanning. The volume nearest the first event began at 22:23 UTC.
1 thunderstorm wind. Local standard time, as filed.
Severe thunderstorm microburst winds caused significant damage to mobile homes at Mescal. At least two mobile homes suffered roof damage or roof collapse. Several awnings on the mobile homes were destroyed. Thunderstorm winds were estimated to be near 70 mph.
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: 184211.