Microburst winds were reported northeast of Yuma as thundertorms moved through the area.
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 PSR wrote it up.
Microburst winds were reported northeast of Yuma as thundertorms moved through the area.
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 Phoenix, AZ wrote its last area forecast discussion before the first event at May 18, 5:45 AM MST, 2 hours 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 545 AM MST MON MAY 18 2009 .UPDATE...UPDATED FIRE WX DISCUSSION. && .SYNOPSIS... ONE MORE DAY OF RECORD OR NEAR RECORD HIGH TEMPERATURES ARE EXPECTED TODAY...MAINLY OVER SOUTH-CENTRAL ARIZONA. A COOLING TREND IS EXPECTED TUESDAY AND WEDNESDAY AS THE HIGH PRESSURE RIDGE WEAKENS AND SHIFTS EASTWARD IN ADVANCE OF AN APPROACHING UPPER LOW PRESSURE SYSTEM. THE APPROACHING LOW WILL AID IN THE DEVELOPMENT OF THUNDERSTORMS OVER ARIZONA WITH A SLIGHT CHANCE OF STORMS OFF AND ON OVER SOUTH-CENTRAL ARIZONA THROUGH THURSDAY EVENING...WITH BETTER CHANCES OVER THE HIGHER TERRAIN. THE EXITING LOW PRESSURE SYSTEM WILL LEAD TO WARMER TEMPERATURES AND DRY CONDITIONS FRIDAY THROUGH SUNDAY. && .DISCUSSION... EAST-SOUTHEASTERLY FLOW ALOFT WILL CONTINUE TODAY DUE TO THE POSITIONING OF THE HIGH CENTERED OVER THE NORTHERN GREAT BASIN AND THE LOW CENTERED WEST OF NORTHERN BAJA MEXICO. TWO MAIN FORECAST CHALLENGES ARE TEMPERATURES AND THUNDERSTORMS. MODELS INDICATE TEMPS TODAY SHOULD BE AS WARM AS SUNDAY AND FORECASTS REFLECT THIS. WILL KEEP SPS GOING TO HIGHLIGHT THE HEAT. CONDITIONS QUITE CLOSE TO EXCESSIVE HEAT THRESHOLDS. IN FACT...107 WOULD TIE THE RECORD FOR PHOENIX. AS THE RIDGE SHIFTS TO THE EAST AND A TROUGH SLOWLY ADVANCES...MAX TEMPERATURES WILL DECREASE SEVERAL DEGREES BEGINNING TUESDAY. EVEN MORE COOLING IS ANTICIPATED WEDNESDAY AS THE LOW CENTER MOVES OVERHEAD AND CONSIDERABLE CLOUDINESS IS EXPECTED. THIS WILL LEAD TO ADDITIONAL COOLING OF 5-10 DEGREES...ESPECIALLY OVER SOUTH-CENTRAL ARIZONA. ANTICIPATE LITTLE CHANGE IN TEMPS THURSDAY WITH THE LOW LINGERING. THUS HIGH TEMPS WILL DROP TO THE LOWER 90S OVER THE SOUTH-CENTRAL DESERTS...A BIT WARMER OVER THE LOWER DESERTS OF SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA. THERE WILL BE A THUNDERSTORM/PRECIP THREAT OFF AND ON OVER THE ARIZONA PORTION OF THE FORECAST AREA THROUGH THURSDAY EVENING. FOR TODAY...00Z RUNS OF GFS AND NAM BOTH INDICATED DRY ADVECTION TAKING PLACE OVER SOUTHEAST ARIZONA DURING THE DAY BUT WITH LINGERING MOISTURE OVER WESTERN PORTIONS OF MARICOPA AND PIMA COUNTIES. HOWEVER THEY BOTH SHOW AN EASTWARD EXPANSION OF MOISTURE TONIGHT. IN LIGHT OF STEERING FLOW AND MODEL VERTICAL MOTION FIELDS...INTRODUCED SLIGHT CHANCE POPS OVER MOST OF THE ARIZONA ZONES FOR TONIGHT. ANY STORMS THAT FORM WILL STRUGGLE TO PRODUCE MUCH PRECIP. THUNDERSTORM THREAT DECLINES TUESDAY AS THE STEERING FLOW BECOMES SOUTH-SOUTHWESTERLY...RELEGATING POPS TO ZONE 24. AS THE LOW CENTER MOVES CLOSER WEDNESDAY AND MORE MOISTURE IS ADVECTED INTO THE AREA POPS WERE REINTRODUCED...MAINLY TO THE SOUTH-CENTRAL DESERTS. THOUGH BOUNDARY LAYERS WONT BE AS UNSTABLE DUE TO THE EXPECTED CLOUDINESS...THE ADDED MOISTURE AND THE PRESENCE OF THE LOW IS EXPECTED TO OFFSET THAT. IT REMAINS TO BE SEEN WHAT KIND OF FORCING WILL BE PRESENT...BUT IT WOULDNT TAKE MUCH TO GET SOME PRECIP IF THE MOISTURE IS THERE. BETTER PRECIP AMOUNTS ARE POSSIBLE WEDNESDAY...BUT PWAT VALUES ARE STILL NOT THAT IMPRESSIVE AS THE MOISTURE IS PRIMARILY MID AND UPPER LEVEL. THE LOW IS PROGGED TO BE SLOW TO MOVE OUT SO POPS REMAIN OVER SOUTH-CENTRAL ARIZONA THROUGH THURSDAY EVENING. FRIDAY THROUGH SUNDAY...THE LOW FINALLY EXITS AND TEMPERATURES SLOWLY CLIMB. HOWEVER NEITHER GFS NOR ECMWF BUILD A STRONG RIDGE INTO THE AREA. IN FACT...BOTH ARE INDICATING SOME SORT OF WEAK TROUGHING DEVELOPING OVER THE SOUTHWEST STATES...BUT IN DIFFERENT CONFIGURATIONS. UNFORTUNATELY...IT LOOKS LIKE TEMPS WILL STILL GET A BIT ABOVE AVERAGE. && .AVIATION... MONSOON-LIKE PATTERN IS IN PLACE ACROSS THE DESERT SOUTHWEST. STEERING FLOW IS SOUTHEASTERLY...CONDUCIVE FOR BRINGING A GUST FRONT UP I-10 AND TOWARDS THE PHOENIX METRO AREA. WILL NOT INDICATE THIS IN THE KPHX AND KIWA TAFS AT THIS TIME. HOWEVER...IF THUNDERSTORMS DO IN FACT DEVELOP SOUTH OF THE AREA LATE THIS AFTERNOON OR EARLY THIS EVENING...AN OUTFLOW BOUNDARY WITH WINDS EXCEEDING 35 KT (AND BLOWING DUST) IS A GOOD BET. OUT WEST IN SE CA...NO AVIATION CONCERNS. JUST SOME MID AND HIGH LEVEL DEBRIS CLOUDINESS. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... BIGGEST THREAT THE NEXT FEW DAYS WILL BE THUNDERSTORMS...SOME DRY THAT HAVE THE POTENTIAL TO IGNITE FIRES ACROSS SOUTH-CENTRAL AZ. FIRE POTENTIAL WILL BE HIGHEST TODAY...GRADUALLY DECREASING THROUGH THE WEEK WITH SLIGHTLY COOLER TEMPERATURES AND INCREASING MOISTURE. ALTHOUGH THE PRESENCE OF DRY FUELS AND AN IGNITION TRIGGER WILL BE IN PLACE...WINDS WILL GENERALLY REMAIN LIGHT AND TERRAIN-DRIVEN THE NEXT FEW DAYS...LIMITING THE SPREAD OF ANY WILDFIRES THAT MAY DEVELOP. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX DISCUSSION...AJ AVIATION...HIRSCH FIRE WEATHER...HIRSCH
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE PHOENIX AZ 615 AM MST MON MAY 18 2009 AZZ020>028-CAZ030>033-190115- LOWER COLORADO RIVER VALLEY AZ-WEST CENTRAL DESERTS- NORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREA- SOUTHERN GILA COUNTY/TONTO NATIONAL FOREST FOOTHILLS- YUMA/MARTINEZ LAKE AND VICINITY-SOUTHWEST DESERTS- SOUTHWEST MARICOPA COUNTY-NORTHWEST AND NORTH CENTRAL PINAL COUNTY- JOSHUA TREE NATIONAL PARK-LOWER COLORADO RIVER VALLEY CA- RIVERSIDE COUNTY/EASTERN DESERTS-IMPERIAL COUNTY- 615 AM MST MON MAY 18 2009 /615 AM PDT MON MAY 18 2009/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST-CENTRAL ARIZONA...EXTREME SOUTHWEST ARIZONA...EXTREME WEST-CENTRAL ARIZONA... SOUTH-CENTRAL ARIZONA...SOUTHWEST ARIZONA...WEST-CENTRAL ARIZONA... EXTREME SOUTHEAST CALIFORNIA AND SOUTHEAST CALIFORNIA. .DAY ONE...TODAY AND TONIGHT THERE WILL BE A SLIGHT CHANCE OF THUNDERSTORMS TODAY AND TONIGHT. ANY STORMS THAT FORM DURING THE AFTERNOON AND EVENING WILL BE EFFECTIVE AT PRODUCING VERY STRONG GUSTY WINDS...POSSIBLY STRONG ENOUGH TO CAUSE DAMAGE. AREAS OF DENSE BLOWING DUST WILL ACCOMPANY THE STRONGER WINDS. ONLY MINOR AMOUNTS OF RAIN...IF ANY...SHOULD BE EXPECTED. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY STORM CHANCES ARE EXPECTED TO BE LIMITED TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA TUESDAY BEFORE EXPANDING TO THE LOWER ELEVATIONS OF SOUTH-CENTRAL AND SOUTHWEST ARIZONA WEDNESDAY AND THURSDAY. STORMS WILL BE CAPABLE OF LOCALLY VERY STRONG WINDS. .SPOTTER INFORMATION STATEMENT... WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX AJ
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE PHOENIX AZ 529 AM MST MON MAY 18 2009 AZZ020>028-CAZ030>033-182300- LOWER COLORADO RIVER VALLEY AZ-WEST CENTRAL DESERTS- NORTHWEST MARICOPA COUNTY-GREATER PHOENIX AREA- SOUTHERN GILA COUNTY/TONTO NATIONAL FOREST FOOTHILLS- YUMA/MARTINEZ LAKE AND VICINITY-SOUTHWEST DESERTS- SOUTHWEST MARICOPA COUNTY-NORTHWEST AND NORTH CENTRAL PINAL COUNTY- JOSHUA TREE NATIONAL PARK-LOWER COLORADO RIVER VALLEY CA- RIVERSIDE COUNTY/EASTERN DESERTS-IMPERIAL COUNTY- INCLUDING THE CITIES OF...EHRENBERG...PARKER...BOUSE...QUARTZSITE... SALOME...BUCKEYE...LAKE PLEASANT...MORRISTOWN...NEW RIVER... TONOPAH...WICKENBURG...CAREFREE...CAVE CREEK...CHANDLER... FOUNTAIN HILLS...GILBERT...GLENDALE...MESA...PEORIA...PHOENIX... SCOTTSDALE...SUN CITY...TEMPE...GLOBE...MIAMI...SAN CARLOS... AND SUPERIOR...ALSO INCLUDING APACHE...BARTLETT...CANYON... HORSESHOE...ROOSEVELT...AND SAGUARO LAKES...FORTUNA FOOTHILLS... SAN LUIS...SOMERTON...YUMA...DATELAND...TACNA...WELLTON... GILA BEND...APACHE JUNCTION...CASA GRANDE...COOLIDGE...FLORENCE... COTTONWOOD VISITOR CENTER...KEYS VIEW...LOST HORSE...BLYTHE... CHIRIACO SUMMIT...DESERT CENTER...EAGLE MOUNTAIN...BRAWLEY... CALEXICO...EL CENTRO...GLAMIS...IMPERIAL...AND THE SALTON SEA 530 PM MST MON MAY 18 2009 /530 AM PDT MON MAY 18 2009/ ...UNUSUALLY HOT TODAY WITH RECORD OR NEAR RECORD TEMPERATURES AT SOME LOCALES... A STRONG HIGH PRESSURE SYSTEM WILL PERSIST OVER THE REGION TODAY ...PRODUCING HIGH TEMPERATURES 10-15 DEGREES ABOVE AVERAGE FOR THE DATE. IN FACT...SOME LOCATIONS IN SOUTH-CENTRAL ARIZONA WILL BE AT OR NEAR RECORD LEVELS...INCLUDING PHOENIX. FORECAST HIGH TEMPERATURES FOR A FEW SELECT STATIONS TODAY INCLUDE... PHOENIX...107...WITH A RECORD OF 107. BLYTHE CALIFORNIA...107 WITH A RECORD OF 110. IMPERIAL CALIFORNIA...106 WITH A RECORD HIGH OF 110. AND PARKER ARIZONA...109 WITH A RECORD OF 108. TODAYS HEAT...ADDED TO THE HEAT EXPERIENCED THIS WEEKEND...COULD POSE HEAT-RELATED DANGERS TO INDIVIDUALS WHO WILL BE OUTDOORS FOR AN EXTENDED PERIOD. IF YOU MUST BE OUTSIDE FOR A PROLONG PERIOD...APPLY SUNBLOCK...WEAR A WIDE-BRIMMED HAT...AND DRINK PLENTY OF WATER. STAY UP-TO-DATE WITH THE LATEST FORECASTS ON WEATHER RADIO...OR FROM THE NATIONAL WEATHER SERVICE PHOENIX INTERNET SITE AT WEATHER.GOV/PHOENIX AJ
1 strong wind. Local standard time, as filed.
Microburst winds reached 55 mph. The blowing dust cut the visibility briefly to zero.
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, May 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: 174691.