Monsoon moisture fueled another round of thunderstorms over the Mojave Desert and southern Great Basin. Several storms produced severe weather and flash flooding.
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.
Monsoon moisture fueled another round of thunderstorms over the Mojave Desert and southern Great Basin. Several storms produced severe weather and flash flooding.
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 11, 2:39 PM MST, 4 hours 54 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 239 PM PDT SAT AUG 11 2012 .SYNOPSIS...A MOIST SOUTHERLY FLOW WILL RESULT IN ISOLATED TO SCATTERED AFTERNOON AND EVENING THUNDERSTORMS THROUGH THE MIDDLE OF NEXT WEEK. MEANWHILE...TEMPERATURES ARE EXPECTED TO BE ABOVE NORMAL THROUGH THE MIDDLE OF NEXT WEEK. && .SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...INVERTED TROUGH PUSHING NORTH INTO THE CWA...WITH A CYCLONIC ROTATION SEEN IN THE CLOUDS LOCATED OVER SOUTHEAST SAN BERNARDINO COUNTY THIS AFTERNOON WILL CONTINUE TO SHIFT NORTHWEST OVERNIGHT. TROUGH HAS NOT PRODUCED THE EXPECTED INCREASE IN THUNDERSTORMS WHICH WAS EARLIER EXPECTED...BUT SHOULD STILL BE A FOCUS FOR LATE AFTERNOON/EVENING. THE MAIN THUNDERSTORM ACTIVITY HAS BEEN AROUND THE PERIPHERY OF THE TROUGH WITH WESTERN SAN BERNARDINO/INYO/ESMERALDA/CENTRAL NYE/LINCOLN AND NORTHERN MOHAVE COUNTIES SEEING ISOLATED ACTIVITY SO FAR TODAY. THE NORTHERN PORTION APPEARS TO BE ALONG THE BOUNDARY BETWEEN THE TAIL END FEATURE OF A SHORT WAVE TROUGH MOVING INTO THE NORTHERN PLAINS AND THE RIDGE CENTERED OVER WESTERN NEW MEXICO. ALTHOUGH ISOLATED ACTIVITY MAY BE SEEN OVERNIGHT...ESPECIALLY ASSOCIATED WITH THE INVERTED TROUGH...HOWEVER...FOR THE MOST PART ACTIVITY SHOULD DECREASE THIS EVENING AND END OVERNIGHT. THE INVERTED TROUGH LOSSES ITS DEFINITION WITH VERY LITTLE FOCUS BEING SEEN ON SUNDAY AS SOUTH TO SOUTHEAST FLOW ALOFT REMAINS OVER THE CWA. THIS CONTINUES INTO MONDAY AS THE OVERALL SYNOPTIC PATTERN KEEPS THE RIDGE CENTERED OVER WESTERN NEW MEXICO. THIS WILL CONTINUE TO ALLOW MOISTURE TO FLOW INTO THE AREA WITH MODELS SHOWING GENERALLY GENERALLY AN INCH OF PW OVER THE CWA WITH 1.25 INCHES OVER MORE OVER THE SOUTH. THIS COMBINED WITH GENERAL -1/-2 LI AND DAYTIME HEATING WILL KEEP THE MAINLY DIURNAL AFTERNOON/EVENING THUNDERSTORM CYCLE GOING THROUGH THE SHORT TERM. CONVECTION SHOULD INITIATE OVER THE HIGHER TERRAIN BEFORE MOVING INTO THE VALLEYS LATE AFTERNOON/EVENING. TEMPERATURES WILL CONTINUE TO BE ABOVE NORMAL THROUGH THE PERIOD. .LONG TERM...TUESDAY THROUGH SATURDAY...MODELS FORECAST A DECENT AMOUNT OF MOISTURE AROUND THE AREA ON TUESDAY. BOTH THE GFS/ECMWF HAVE A WEAK UPPER LEVEL CIRCULATION OFF THE CALIFORNIA COAST WHICH MAY PROVIDE DYNAMIC SUPPORT FOR STORM DEVELOP...ESPECIALLY ACROSS THE SOUTHERN SIERRA AND THE NORTHERN ZONES. SOME DRYING IS INDICATED BEYOND TUESDAY AND THUNDERSTORM CHANCES SHOULD DECREASE OVER THE CWA LACKING ANY SO FAR UNRESOLVED TRIGGER FEATURE. MODELS SHOW AN AREA OF DEFORMATION NORTHWEST OF THE CWA ON WEDNESDAY WHICH SHOULD NOT HAVE AN IMPACT FOR OUR AREA. THE THURSDAY AND FRIDAY MODEL FORECAST RAISES MORE QUESTIONS THAN IT GIVES ANSWERS AS THE AFOREMENTIONED DEFORMATION ZONE MOVES EAST OF ITS PREVIOUS DAY FORECASTED POSITION AND COULD BEGIN TO BRING FOCUS FOR STORM DEVELOPMENT ACROSS MUCH OF THE NORTHERN FORECAST AREA. IN ADDITION...THE 12Z ECMWF IS WAY MORE BULLISH ON ADVECTING TROPICAL MOISTURE INTO THE FORECAST AREA BY FRIDAY. WITHOUT QUESTION...THE UNCERTAINTY FROM THURS/FRI CARRIES INTO SATURDAY. TEMPERATURES WILL BE MOISTURE/CLOUD/STORM DEPENDENT BUT FOR NOW MODELS POINT TO WARMER CONDITIONS TUE/WED FOLLOWED BY MORE NORMAL TEMPERATURES THU-SAT. && .AVIATION...FOR MCCARRAN...THUNDERSTORMS ARE SLOW TO DEVELOP TODAY OTHER THAN A FEW STORMS OVER THE SHEEP RANGE AND SPRING MTNS. VCTS WAS REMOVED FROM THE KLAS TAF COMPLETELY BASED ON TRENDS BUT MAY NEED TO BE REINTRODUCED AT SOME POINT LATER THIS AFTERNOON OR EARLY EVENING. WIND DIRECTION AND SPEED HAVE BEEN ALL OVER THE PLACE SO FAR TODAY BUT SHOULD GENERALLY BE OUT OF THE SOUTH THROUGH THE AFTERNOON AND OCCASIONALLY GUSTY THEN BECOMING MORE SOUTHWEST THIS EVENING. GUSTY AND ERRATIC OUTFLOW WINDS MAY BE MORE OF A FACTOR LATER ON AS WELL. TEMPERATURES ARE EXPECTED TO DROP BELOW 100F AROUND 05Z. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...ISOLATED TO SCATTERED THUNDERSTORMS TO CONTINUE OVER MUCH OF THE REGION TODAY LEADING TO GUSTY AND ERRATIC WINDS AT TIMES AT THE TAF SITES. OUTSIDE OF THUNDERSTORM INFLUENCES...WINDS ARE SHOULD FAVOR A SOUTHERLY DIRECTION AROUND 10-15KTS THROUGH THE AFTERNOON BECOMING DIURNALLY DRIVEN TONIGHT. CLOUDS MAINLY FEW-SCT080-100 AND SCT-BKN120-140. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...NONE. AZ...NONE. CA...NONE. && JENSEN/SALMEN HTTP://WEATHER.GOV/LASVEGAS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LAS VEGAS NV 449 AM PDT SAT AUG 11 2012 AZZ001>003-036-CAZ519>527-NVZ014>022-120700- 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- 449 AM PDT SAT AUG 11 2012 /449 AM MST SAT AUG 11 2012/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST ARIZONA...SOUTHEAST CALIFORNIA AND SOUTHERN NEVADA. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS CAN BE EXPECTED ACROSS MUCH OF THE AREA THROUGH THIS EVENING THOUGH SOUTHEAST CALIFORNIA AND SOUTHERN NEVADA WILL LIKELY SEE THE HIGHEST CONCENTRATION OF STORMS AS A DISTURBANCE MOVES UP THROUGH SOUTHEAST CALIFORNIA. THE MAIN HAZARD ASIDE FROM LIGHTNING WILL BE THE POTENTIAL FOR HEAVY RAIN AND FLASH FLOODING WITH A FEW OF THE STORMS. STRONG GUSTY WINDS MAY ALSO OCCUR. .DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY ISOLATED TO SCATTERED THUNDERSTORMS CAN BE EXPECTED EACH DAY THROUGH AT LEAST WEDNESDAY WITH COVERAGE DECREASING SOMEWHAT ACROSS SOUTHEAST CALIFORNIA AND SOUTHERN NEVADA AFTER MONDAY. .SPOTTER INFORMATION STATEMENT... THERE IS A POSSIBILITY OF SPOTTER ACTIVATION THIS AFTERNOON... PARTICULARLY FOR SAN BERNARDINO AND CLARK COUNTIES DEPENDING ON THUNDERSTORM COVERAGE AND INTENSITY. SPOTTERS ARE ALSO ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. JA
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
324 PM PDT SAT AUG 11 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0235 PM HAIL SSE LANDERS (AR190) 34.22N 116.41W
08/11/2012 E0.25 INCH SAN BERNARDINO CA TRAINED SPOTTER
0249 PM FLASH FLOOD 1 NNW YUCCA VALLEY 34.13N 116.44W
08/11/2012 SAN BERNARDINO CA TRAINED SPOTTER
6 INCHES OF WATER FLOWING DOWN THE CENTER OF BUENA VISTA
DRIVE.
0253 PM HEAVY RAIN 3 W LANDERS (AR190) 34.23N 116.46W
08/11/2012 M0.20 INCH SAN BERNARDINO CA TRAINED SPOTTER
SPOTTER IN YUCCA VALLEY REPORTS 0.2 INCHES OF RAIN IN A 5
MINUTE PERIOD.
&&
METZGERThe Las Vegas radar (KESX), 94 km away, was scanning. The volume nearest the first event began at 02:32 UTC.
1 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Bank Street was completely under water near the high school.
Thunderstorm winds knocked down two trees near Airway and Heather.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2012Every state in 2012This day in weather historyWarnings in Arizona, 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: 397507, 397508.