Another surge of monsoon moisture led to an outbreak of thunderstorms over the Mojave Desert and southern Great Basin. A low pressure system further enhanced the storms on the 22nd.
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 VEF wrote it up.
Another surge of monsoon moisture led to an outbreak of thunderstorms over the Mojave Desert and southern Great Basin. A low pressure system further enhanced the storms on the 22nd.
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 22, 1:55 AM PST, 8 hours 10 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 255 AM PDT WED AUG 22 2012 .SYNOPSIS...SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED TODAY AND INTO THURSDAY AS MONSOON MOISTURE REMAINS IN PLACE AND A WEAK LOW PRESSURE SYSTEM MOVES OVER THE AREA. HEAVY RAIN...HAIL AND GUSTY WINDS ARE POSSIBLE WITH THESE THUNDERSTORMS. GRADUAL DRYING TAKES PLACE FRIDAY THROUGH MONDAY. TEMPERATURES ARE EXPECTED TO BE NEAR TO SLIGHTLY BELOW NORMAL THROUGH THE WEEKEND. && .SHORT TERM...TODAY THROUGH FRIDAY...FAIRLY ACTIVE MORNING AS SCATTERED THUNDERSTORMS ARE CONTINUING ACROSS NORTHERN MOHAVE/NORTHEAST CLARK/LINCOLN COUNTIES WITH ISOLATED ACTIVITY ACROSS SOUTHERN NYE AND INYO COUNTIES. THIS EARLY MORNING ACTIVITY IS DUE TO THE INCREASING MID/UPPER LEVEL DYNAMICS THAT IS BEING GENERATED BY A WEAK LOW PUSHING ONTO THE CENTRAL CALIFORNIA COAST. MODELS INDICATE THAT A JET NUDGING OVER SOUTHERN NEVADA/PRECIPITABLE WATER VALUES OVER AN INCH CWA WIDE AND APPROACHING TWO INCHES OVER THE EXTREME SOUTHERN PORTION/LI VALUES TRENDING TOWARDS -4 OR LOWER BY THIS AFTERNOON AND THE CONTINUED DYNAMICS OF THE WEAK LOW AS IT SLOWLY SHIFTS EAST DURING THE DAY WILL CONTINUE TO KEEP NUMEROUS SHOWERS/THUNDERSTORMS GOING ACROSS MUCH OF THE CWA THROUGH THE DAY. THE FLASH FLOOD WATCH WHICH WAS ORIGINALLY SUPPOSED TO START AT 18Z WILL BE CHANGED TO START WITH THE ISSUANCE OF THE MORNING FORECAST. THE UPPER LOW IS EXPECTED TO BE CENTERED OVER THE INYO/NYE COUNTY BORDER BY 06Z THURSDAY WHICH SHOULD RESULT IN SCATTERED THUNDERSTORMS CONTINUING THROUGH MUCH OF TONIGHT OVER THE EASTERN PORTION OF THE CWA. WILL NEED TO LOOK AT POSSIBLY EXTENDING THE FLASH FLOOD WATCH FOR THIS AREA IN LATER PACKAGES. BY THURSDAY MOIST AND UNSTABLE CONDITIONS CONTINUE OVER LINCOLN/CLARK/MOHAVE COUNTIES WITH SCATTERED THUNDERSTORMS EXPECTED TO CONTINUE. PRECIPITABLE WATER VALUES DECREASE BUT STILL EXPECTED TO BE OVER 1.25 INCHES...RESULTING IN ISOLATED FLASH FLOOD PROBLEMS. A MORE STABLE AIRMASS THEN MOVES OVER THE REGION ON FRIDAY AS THE LOW SHIFTS WELL EAST OF THE AREA. HOWEVER THE MOISTURE IS STILL NOT TOTALLY FLUSHED OUT OF THE EASTERN PORTION OF THE CWA...ESPECIALLY MOHAVE COUNTY AND WILL CONTINUE TO SHOW ISOLATED CONVECTION FOR FRIDAY. TEMPERATURES...ESPECIALLY TODAY WILL BE BELOW NORMAL DUE TO THE AMOUNT OF EXPECTED CLOUD COVER/THUNDERSTORM ACTIVITY...WITH BELOW NORMAL TEMPERATURES THEN CONTINUING ON THURSDAY AND FRIDAY. && .LONG TERM...MOSTLY DRY CONDITIONS ARE EXPECTED SATURDAY THROUGH TUESDAY...GENERALLY SPEAKING ANYWAY AND RELATIVE TO THE EXPECTED WEATHER FOR TODAY. HOWEVER...MODELS DO STILL FORECAST A DECENT AMOUNT OF MOISTURE AND WEAK INSTABILITY EACH AFTERNOON AND EVENING OVER THE EASTERN REGIONS OF THE CWA...MAINLY MOHAVE COUNTY. THIS WILL KEEP A FEW STORMS FIRING ALMOST EVERY DAY. TEMPERATURES SHOULD RISE TO NORMAL LEVELS BY THE END OF THE WEEKEND OR EARLY NEXT WEEK. && .AVIATION...FOR MCCARRAN..THUNDERSTORMS COVERAGE WILL LIKELY INCREASE THIS MORNING AND CONTINUE THROUGH TONIGHT IN ALL THE APPROACH CORRIDORS. PIN POINTING TIMING OF DEVELOPMENT IN THE VALLEY IS MORE DIFFICULT HOWEVER AND WILL HAVE TO SEE HOW THINGS PROGRESS OVER THE NEXT SEVERAL HOURS. CIGS AOB 5K FEET POSSIBLE AT TIMES NEAR THUNDERSTORMS WITH A MORE GENERAL CIG BASE AT 8K FEET THIS AFTERNOON. AWAY FROM THUNDERSTORM INFLUENCES...WINDS WILL BE SOUTH AROUND 10KTS. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...ISOLATED TO SCATTERED THUNDERSTORM COVERAGE IS EXPECTED THROUGH TODAY WITH A MARKED INCREASE IN COVERAGE AFTER 18Z...WITH EMPHASIS ON THE EASTERN HALF OF THE CWA. CIGS DOWN TO 5K FEET AT TIMES BUT GENERALLY 8-10K FEET. SOUTH WINDS 10-15KTS ARE EXPECTED AWAY FROM STORM INFLUENCES. && && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR NVZ015>022. AZ...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR AZZ001>003-036. CA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR CAZ522>527. && JENSEN/SALMEN HTTP://WEATHER.GOV/LASVEGAS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LAS VEGAS NV 458 AM PDT WED AUG 22 2012 AZZ001>003-036-CAZ522>527-NVZ015>022-230300- NORTHWEST PLATEAU-LOWER COLORADO RIVER VALLEY-NORTHWEST DESERTS- LAKE MEAD NATIONAL RECREATION AREA-DEATH VALLEY NATIONAL PARK- WESTERN MOJAVE DESERT-EASTERN MOJAVE DESERT-MORONGO BASIN- CADIZ BASIN-SAN BERNARDINO COUNTY-UPPER COLORADO RIVER VALLEY- LINCOLN COUNTY-NORTHEAST CLARK COUNTY- WESTERN CLARK AND SOUTHERN NYE COUNTY-SHEEP RANGE- SPRING MOUNTAINS-LAS VEGAS VALLEY-SOUTHERN CLARK COUNTY- 458 AM PDT WED AUG 22 2012 /458 AM MST WED AUG 22 2012/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST ARIZONA...CALIFORNIA AND SOUTHERN NEVADA. .DAY ONE...TODAY AND TONIGHT MOIST AND UNSTABLE CONDITIONS WILL CONTINUE OVER THE AREA...RESULTING IN ISOLATED TO SCATTERED THUNDERSTORMS. BRIEF HEAVY RAINFALL MAY BE SEEN FROM THESE STORMS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY ISOLATED THUNDERSTORMS ARE EXPECTED ONCE AGAIN THURSDAY AFTERNOON. NO HAZARDOUS WEATHER IS EXPECTED FRIDAY THROUGH TUESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED FOR TODAY. HOWEVER... SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. CAZ519>521-NVZ014-230300- EASTERN SIERRA SLOPES-OWENS VALLEY-WHITE MOUNTAINS OF INYO COUNTY- ESMERALDA AND CENTRAL NYE COUNTY- 458 AM PDT WED AUG 22 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CALIFORNIA AND SOUTHERN NEVADA. .DAY ONE...TODAY AND TONIGHT A FLASH FLOOD WATCH IS IN EFFECT THROUGH LATE TONIGHT AS A VERY MOIST AND UNSTABLE AIR MASS COMBINES WITH A WEAK LOW PRESSURE AREA TO RESULT IN WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY DURING THE DAY AND TONIGHT. THESE THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE HEAVY DOWNPOURS IN A VERY SHORT PERIOD OF TIME. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY IMPROVING CONDITIONS WILL BE SEEN FROM THE WEST ON THURSDAY...HOWEVER ISOLATED TO SCATTERED THUNDERSTORMS WILL CONTINUE OVER MAINLY LINCOLN/CLARK/MOHAVE COUNTIES ON THURSDAY. THESE THUNDERSTORMS WILL STILL HAVE THE POTENTIAL OF PRODUCING ISOLATED FLASH FLOOD PROBLEMS. BY FRIDAY AND INTO THE WEEKEND... THUNDERSTORMS WILL BE CONFINED TO MAINLY MOHAVE COUNTY SATURDAY THROUGH TUESDAY. .SPOTTER INFORMATION STATEMENT... DUE TO THE FLASH FLOOD WATCH IN EFFECT...SPOTTER ACTIVATION MAY BE REQUESTED LATER TODAY.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
839 AM PDT WED AUG 22 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0825 AM FLOOD E OVERTON 36.53N 114.44W
08/22/2012 CLARK NV LAW ENFORCEMENT
HIGHWAY 169 CLOSED NEAR WHITMORE STREET SOUTH OF OVERTON.
&&
BPPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
847 AM PDT WED AUG 22 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0700 PM TSTM WND DMG ESE LOGANDALE 36.62N 114.48W
08/21/2012 CLARK NV PUBLIC
PUBLIC REPORTED FENCE AND HOUSE DAMAGE DUE TO STRONG
WINDS. PARTY STATED THAT 8 TO 10 POUND ROCKS WERE BEING
THROWN INTO HIS HOUSE CAUSING DAMAGE TO THE STUCCO. PARTY
ALSO STATED THAT THE FENCE SURROUNDING HIS CATTLE PEN WAS
BLOWN DOWN DUE TO THE WIND. NO WIND ESTIMATION WAS GIVEN.
ESTIMATED DAMAGE TO PROPERTY WAS APPROXIMATELY 1,500
DOLLARS.
&&
ASGPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
854 AM PDT WED AUG 22 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0730 AM HEAVY RAIN 2 NE MESQUITE 36.81N 114.05W
08/22/2012 M2.04 INCH MOHAVE AZ CO-OP OBSERVER
CO-OP OBSERVER HAS BEEN KEEPING RAINFALL RECORDS SINCE
JANUARY 1992. THIS 24 HOUR AMOUNT BROKE HIS PREVIOUS 24
HOUR RECORD OF 1.82 INCHES ON 30 NOVEMBER 2007.
&&
BFUISThe Las Vegas radar (KESX), 80 km away, was scanning. The volume nearest the first event began at 18:06 UTC.
10 flash flood. Local standard time, as filed.
The Mid Hills and Hole in the Wall campgrounds in the Mojave National Preserve were cut off by flash flooding, stranding campers.
Water flowed over Highway 62 at Sunburst Street, leaving mud and debris on the highway.
Several unpaved roads were closed due to flooding in the southeast part of the Mojave National Preserve. Sections of paved roads were covered with debris and grapefruit sized rocks.
Rocks and debris were washed across the Bailey Road off ramp from I-15 North.
Amboy Road was closed near Shadow Mountain Road due to flash flooding.
Water with rocks and debris ran across Highway 62 near Godwin Road.
One foot of water and debris flowed across Goffs Road. A truck was stuck in the water.
Highway 136 was closed between Highways 395 and 190 due to flash flooding.
Flash flooding caused significant pavement damage to Scotty's Castle Road between the castle and the Death Valley National Park boundary. The road to Ubehebe Crater was also closed due to flooding.
Highway 95 was closed due to water and debris flowing across the road in multiple places from mile marker 61 to just south of the Nevada state line. A big rig was stalled in one of the flooded areas.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2012Every state in 2012This day in weather historyWarnings in California, August 2012
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: 400906, 400907, 400908, 400909, 400910, 400911, 400912, 400913, 400914, 400915.