An upper level disturbance and monsoon moisture combined to trigger an outbreak of thunderstorms across the Mojave Desert.
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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 VEF wrote it up.
An upper level disturbance and monsoon moisture combined to trigger an outbreak of thunderstorms across the Mojave Desert.
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 Las Vegas, NV wrote its last area forecast discussion before the first event at Aug 23, 8:50 AM PST, 5 hours 21 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 950 AM PDT SUN AUG 23 2009 .SYNOPSIS...A TROUGH OF LOW PRESSURE WILL MOVE INLAND TODAY BRINGING SCATTERED SHOWERS AND THUNDERSTORMS...WHICH WILL LINGER INTO MONDAY. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH MONDAY...THEN A DRYING AND WARMING TREND IS EXPECTED FOR TUESDAY THROUGH THE END OF THE WEEK. && .UPDATE...GEARING UP FOR POTENTIAL SEVERE WEATHER TODAY. CURRENT FORECAST HAS THAT COVERED AND NO UPDATE PLANNED. && .AVIATION...FOR MCCARRAN...MOSTLY SUNNY SKIES THIS MORNING BECOMING PARTLY CLOUDY THIS AFTERNOON AS THUNDERSTORMS FORM OVER THE LOCAL MOUNTAINS. VALLEY THUNDERSTORMS BECOME A POSSIBILITY THIS AFTERNOON AND EVENING. CURRENT LIGHT WINDS WILL BECOME SOUTHEAST IN THE LATE MORNING AND THEN SOUTH TO SOUTHWEST THIS AFTERNOON AROUND 10 TO 15KTS EXCEPT NEAR THUNDERSTORMS AND OUTFLOW BOUNDARIES. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...MOSTLY CLEAR SKIES SOUTH WITH PARTLY CLOUDY CONDITIONS NORTH THIS MORNING. INCREASING CLOUD COVER AND THUNDERSTORM ACTIVITY BEGINNING OVER THE HIGHER TERRAIN BY EARLY AFTERNOON AND THEN IN THE VALLEY LOCATIONS LATE AFTERNOON AND EVENING. WINDS GENERALLY WILL BE UNDER 10KTS BUT ERRATIC AND GUSTY NEAR THUNDERSTORMS AND OUTFLOW BOUNDARIES. && .PREV DISCUSSION... 308 AM PDT SUN AUG 23 2009 .SHORT TERM...SKIES HAD CLEARED OUT ACROSS THE SOUTHERN ZONES EARLY THIS MORNING WHILE CLOUDS AND LIGHT SHOWERS ASSOCIATED WITH AN EXITING SHORTWAVE WERE MOVING ACROSS THE NORTH. THE TROUGH THAT HAS BEEN OFFSHORE WILL MOVE INLAND TODAY AND WILL COMBINE WITH LEFT OVER MOISTURE AND MORNING SUNSHINE TO GENERATE SCATTERED TO NUMEROUS THUNDERSTORMS THIS AFTERNOON AND EVENING. MODEL SOUNDINGS INDICATE THE POTENTIAL FOR ISOLATED SEVERE THUNDERSTORMS ACROSS PORTIONS OF SAN BERNARDINO...CLARK AND MOHAVE COUNTIES WITH LIFTED INDEX VALUES AROUND -6 AND POSITIVE BUOYANT ENERGY 1500 TO 2000 JOULES. IN ADDITION A JET MAX WILL BE MOVING INTO THE AREA PROVIDING LIFT AND SHEAR. THE TROUGH WILL BE SLOW TO MOVE EAST AND WILL STILL BE IN THE AREA MONDAY WITH A CHANCE OF THUNDERSTORMS OVER MOST OF THE AREA EXCEPT WESTERN SAN BERNARDINO COUNTY. A DRIER AND MORE STABLE AIR MASS WILL START TO MOVE IN TUESDAY BEHIND THE TROUGH WITH ISOLATED THUNDERSTORMS CONFINED TO EASTERN LINCOLN AND NORTHEAST MOHAVE COUNTY. TEMPERATURES WILL REMAIN 5 OR 6 DEGREES BELOW NORMAL TODAY AND WILL WARM SLIGHTLY MONDAY AND TUESDAY. .LONG TERM...STRONG HIGH PRESSURE BUILDS BACK OVER THE DESERT SOUTHWEST AND SOUTHERN GREAT BASIN DURING THE EXTENDED PERIOD. THERE IS VERY LITTLE QUESTION THAT TEMPERATURES WILL WARM BACK TO ABOVE NORMAL UNDER THIS SCENARIO. HOWEVER...THE BIG QUESTION REMAINS TO BE JUST HOW EFFECTIVELY DOES MOISTURE GET SCOURED OUT PRIOR TO THE HIGH RE-CENTERING OVERHEAD. THIS COULD EASILY BE A CASE WHERE MOISTURE BECOMES TRAPPED UNDER THE HIGH AND IS RE-CYCLED DAILY FOR DAYTIME THUNDERSTORMS. FOR NOW...MAINTAINED A DRY FORECAST BUT THE POSSIBILITY SHOULD BE CONSIDERED IN FUTURE PACKAGES. .AVIATION...FOR MCCARRAN...MOSTLY SUNNY SKIES THIS MORNING BECOMING PARTLY CLOUDY THIS AFTERNOON AS THUNDERSTORMS FORM OVER THE LOCAL MOUNTAINS. VALLEY THUNDERSTORMS BECOME A POSSIBILITY THIS AFTERNOON AND EVENING. CURRENT LIGHT WINDS WILL BECOME SOUTHEAST TO SOUTH AROUND 10KTS TODAY EXCEPT NEAR THUNDERSTORMS AND OUTFLOW BOUNDARIES. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...MOSTLY CLEAR SKIES SOUTH WITH PARTLY CLOUDY CONDITIONS NORTH THIS MORNING. INCREASING CLOUD COVER AND THUNDERSTORM ACTIVITY BEGINNING OVER THE HIGHER TERRAIN BY EARLY AFTERNOON AND THEN IN THE VALLEY LOCATIONS LATE AFTERNOON AND EVENING. WINDS GENERALLY WILL BE UNDER 10KTS BUT ERRATIC AND GUSTY NEAR THUNDERSTORMS AND OUTFLOW BOUNDARIES. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...NONE. CA...NONE. && MORGAN/JACQUES/HARRISON/SALMEN HTTP://WEATHER.GOV/LASVEGAS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LAS VEGAS NV 542 AM PDT SUN AUG 23 2009 AZZ001>003-036-CAZ519>527-NVZ014>022-240500- NORTHWEST PLATEAU-LOWER COLORADO RIVER VALLEY-NORTHWEST DESERTS- LAKE MEAD NATIONAL RECREATION AREA-EASTERN SIERRA SLOPES- OWENS VALLEY-WHITE MOUNTAINS OF INYO COUNTY- DEATH VALLEY NATIONAL PARK-WESTERN MOJAVE DESERT- EASTERN MOJAVE DESERT-MORONGO BASIN-CADIZ BASIN- SAN BERNARDINO COUNTY-UPPER COLORADO RIVER VALLEY- ESMERALDA AND CENTRAL NYE COUNTY-LINCOLN COUNTY- NORTHEAST CLARK COUNTY-WESTERN CLARK AND SOUTHERN NYE COUNTY- SHEEP RANGE-SPRING MOUNTAINS-LAS VEGAS VALLEY- SOUTHERN CLARK COUNTY- 542 AM PDT SUN AUG 23 2009 /542 AM MST SUN AUG 23 2009/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST ARIZONA...CALIFORNIA AND SOUTHERN NEVADA. .DAY ONE...TODAY AND TONIGHT A MOIST AND UNSTABLE AIR MASS IS IN PLACE OVER THE AREA. A LOW PRESSURE SYSTEM APPROACHING FROM THE WEST AND SOLAR HEATING WILL COMBINE WITH THIS AIR MASS TO GENERATE SCATTERED TO NUMEROUS THUNDERSTORMS THIS AFTERNOON AND EVENING. THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN SAN BERNARDINO COUNTY AND MUCH OF CLARK AND MOHAVE COUNTIES. SEVERE THUNDERSTORMS PRODUCE WIND GUSTS 58 MPH OR GREATER AND HAIL AN INCH OR MORE IN DIAMETER. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY ISOLATED TO SCATTERED THUNDERSTORMS WILL LINGER MONDAY AS THE LOW PRESSURE SYSTEM CONTINUES TO MOVE SLOWLY ACROSS THE AREA. A DRIER AND MORE STABLE AIR MASS WILL MOVE IN BEGINNING TUESDAY WITH HIGH PRESSURE BUILDING OVER THE AREA THROUGH THE END OF THE WEEK. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS POSSIBLE LATE THIS MORNING OR EARLY THIS AFTERNOON. SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
The Las Vegas radar (KESX), 44 km away, was scanning. The volume nearest the first event began at 22:13 UTC.
1 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Nipton Road (NV Highway 164) was closed due to flooding.
The Henderson Airport AWOS measured a 58 mph wind gust at 527 PM. 13 minutes later, the same thunderstorm blew down three 15-foot tall mesquite trees at the intersection of Pecos and Pebble.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2009Every state in 2009This day in weather historyWarnings in Nevada, 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: 187070, 187069.