A slow moving upper level low and monsoon moisture fueled thunderstorms over the Mojave Desert. Many storms produced flash flooding and severe weather.
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.
A slow moving upper level low and monsoon moisture fueled thunderstorms over the Mojave Desert. Many storms produced flash flooding and severe weather.
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 Sep 13, 2:45 AM PST, 5 hours 15 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 345 AM PDT TUE SEP 13 2011 .SYNOPSIS...AN AREA OF LOW PRESSURE WILL SLOWLY MOVE ACROSS SOUTHERN CALIFORNIA AND SOUTHERN NEVADA THEN INTO ARIZONA THROUGH THE MIDDLE OF THE WEEK LEADING TO A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS EACH DAY...WITH SOME STORMS PERSISTING OVERNIGHT. HEAVY RAIN AND HAIL WILL OCCUR WITH STRONGER THUNDERSTORMS. A DRIER SOUTHWEST FLOW WILL DEVELOP OVER THE REGION GOING INTO THE WEEKEND WITH TEMPERATURES REMAINING A LITTLE BELOW NORMAL. && .SHORT TERM...TODAY THROUGH THURSDAY NIGHT...STORMS DIMINISHED SOME LATE IN THE EVENING BUT SINCE MIDNIGHT AREAL EXTENT OF THUNDERSTORMS HAS INCREASED IN CLARK...MOHAVE AND EASTERN SAN BERNARDINO COUNTY. BRIEF HEAVY RAIN IS THE ISSUE WITH STORMS AS A FEW OF THE CLARK COUNTY AND MOHAVE COUNTY ALERT STATIONS HAVE RECORDED ABOUT A THIRD OF AN INCH OF RAINFALL OVER A 20 MINUTE PERIOD. UPPER LOW JUST OFF THE SOUTHERN CALIFORNIA COAST THIS MORNING IS PROGGED BY THE MODELS TO SHIFT INLAND AND BE OVER THE MOJAVE DESERT BY LATE THIS EVENING. UPPER LOW HAS ITS SIGHTS ON THE SOUTHERN HALF OF THE FORECAST AREA WITH NEAR STORM ENVIRONMENT THAT PRODUCED LARGE HAIL SUNDAY AND MONDAY...TRANSITIONING INTO HEAVY RAIN MAKERS TODAY. POSITIVE VORTICITY ADVECTION...WELL ABOVE NORMAL PRECIPITABLE WATER VALUES AND IF MODEL PROGGED LIFTED INDICES/CAPE VALUES ARE REALIZED IT WILL CONTINUE TO BE QUITE ACTIVE IN CLARK...SAN BERNARDINO AND MOHAVE COUNTIES. THE POTENTIAL OF CELLS TRAINING LEADS TO A HIGHER POTENTIAL OF FLASH FLOODING AS WELL SO DECIDED TO ISSUE A FLASH FLOOD WATCH WHICH WILL RUN THROUGH MIDNIGHT FOR PORTIONS CLARK...SAN BERNARDINO AND MOHAVE COUNTIES. LITTLE CHANGE WAS DONE TO THE WEDNESDAY AND THURSDAY PERIODS AS LOW EVER SO SLOWLY MOVES INTO ARIZONA. .LONG TERM...MODELS REMAIN IN SO-SO AGREEMENT THROUGH THE MIDDLE OF NEXT WEEK. A WEAK MID-LEVEL RIDGE IS EXPECTED TO GET PUSHED EAST OF NEVADA ON FRIDAY BY A TROUGH IN THE MID AND UPPER LEVELS THAT SWINGS INTO THE WEST COAST. BOTH THE GFS AND ECMWF SHOW 700-500 MB LAYER RELATIVE HUMIDITY VALUES OF AT LEAST 60 PERCENT ACROSS MOST OF OUR AREA AND KEEP SOME MARGINAL INSTABILITY OVER PORTIONS OF THE AREA MAINLY BEING MOHAVE...CLARK AND LINCOLN COUNTIES. THUS...BATCHES OF CLOUDS SHOULD STILL BE AROUND AND THE POSSIBILITY OF A FEW SHOWERS AND THUNDERSTORMS WILL LINGER ON FRIDAY IN THE AFTERNOON AND EVENING HOURS. WE KEPT IN SLIGHT CHANCE POPS OVER MOST OF MOHAVE AND EASTERN LINCOLN COUNTIES AS WELL AS PARTS OF THE EASTERN SOUTHERN SIERRA AND THE WHITE MOUNTAINS. THE LATEST MODELS ARE IN BETTER AGREEMENT WITH KEEPING THIS A TROUGH RATHER THAN CLOSING OFF AN AREA OF LOW PRESSURE AS SOME PREVIOUS RUNS SHOWED...AND THUS LEANED WITH THIS IDEA FOR THE FORECAST. AS THE TROUGH SWINGS INLAND ON SATURDAY...THE TROUGH SHOULD INTERACT WITH WHATEVER MOISTURE IS IN PLACE TO TRIGGER A FEW SHOWERS AND THUNDERSTORMS. ONCE AGAIN THIS LOOKS TO MAINLY BE IN MOHAVE AND EASTERN LINCOLN COUNTIES AND THE WHITE MOUNTAINS. THE TROUGH SHOULD ENHANCE AFTERNOON AND EVENING WINDS SLIGHTLY WITH GUSTS OF 20-30 MPH FROM THE SOUTHWEST A POSSIBILITY BOTH FRIDAY AND SATURDAY AFTERNOONS. HIGH TEMPS ARE FORECAST TO BE A FEW DEGREES BELOW NORMAL. BY SUNDAY DRY NORTHWEST FLOW SHOULD TAKE OVER BEHIND THE TROUGH THOUGH SOME HIGH LEVEL CLOUDS LOOK TO BE AROUND. THE ECMWF AND THE GFS OPERATIONAL RUNS AND ENSEMBLES AGREE TO BUILDING IN AN MID AND UPPER LEVEL RIDGE INTO SOCAL BY NEXT TUESDAY AND WEDNESDAY. THIS SHOULD LEAD TOWARDS A WARMING TREND WITH RISING HEIGHTS. 500 MB HEIGHTS ARE SHOWN TO BE NEAR 590 DM...SO IF THIS VERIFIES WE SHOULD EASILY SEE ABOVE NORMAL HIGH TEMPERATURES BY THE MIDDLE OF NEXT WEEK. THE LAST TRIPLE DIGITS OF 2011 MAY BE IN STORE FOR LAS VEGAS IN THIS TIME PERIOD. && .AVIATION...FOR MCCARRAN...A MOIST AND UNSTABLE ATMOSPHERE WILL KEEP SHRA AND TSRA AROUND THROUGH TONIGHT IN AND AROUND THE LAS VEGAS VALLEY. THE MOST LIKELY PERIOD FOR ACTIVITY SHOULD BE AFTER 17Z TUESDAY AND THIS IS WHEN THE COVERAGE OF SHRA/TSRA IN AND AROUND THE VALLEY AND IN THE APPROACH CORRIDORS SHOULD INCREASE. THUS WITH THE POSSIBILITY OF SHRA/TSRA AROUND AT ANYTIME AND THE CHALLENGE OF TIMING INDIVIDUAL ROUNDS OF ACTIVITY WILL KEEP THE TAF KIND OF GENERIC IN LATER PERIODS AND TIME LIKELY WITH AMENDMENTS WHAT GOES ON IN THE EARLIER PERIODS OF THE TAF WHERE CONFIDENCE WILL BE GREATER ON WHAT TAKES PLACE. THE MAIN THREATS IN AND NEAR SHRA/TSRA WILL BE GUSTY AND ERRATIC WINDS AND REDUCED CIGS AND VSBY. OTHERWISE WINDS WILL FAVOR DIURNAL DIRECTIONAL TRENDS WITH MAINLY BKN CLOUDS AOA 8K-12K FEET. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...SCT SHRA/TSRA WILL CONTINUE THROUGH TONIGHT ACROSS THE AREA. THE GREATEST COVERAGE OF ACTIVITY AND THUS CHANCES OF IT WILL BE OVER MOHAVE...CLARK...AND EASTERN SAN BERNARDINO COUNTIES. THE MAIN THREATS IN AND NEAR SHRA/TSRA WILL BE GUSTY AND ERRATIC WINDS AND REDUCED CIGS AND VSBY. OTHERWISE WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONS WITH MAINLY BKN CLOUDS AOA 8K-12K FEET. THE COVERAGE OF STORMS SHOULD BE GREATEST BETWEEN 17Z TUESDAY AND 06Z WEDNESDAY. CONFIDENCE IN THE TAFS WITH RESPECT TO SHRA/TSRA IS GREATEST IN EARLIEST PERIODS AND REDUCED IN LATER. && .VEF WATCHES/WARNINGS/ADVISORIES... NV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR NVZ020>022. AZ...FLASH FLOOD WATCH THROUGH THIS EVENING FOR AZZ002-003-036. CA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR CAZ524>527. && PIERCE/STACHELSKI HTTP://WEATHER.GOV/LASVEGAS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LAS VEGAS NV 423 AM PDT TUE SEP 13 2011 AZZ002-003-036-CAZ524>527-NVZ020>022-140700- LOWER COLORADO RIVER VALLEY-NORTHWEST DESERTS- LAKE MEAD NATIONAL RECREATION AREA-EASTERN MOJAVE DESERT- MORONGO BASIN-CADIZ BASIN-SAN BERNARDINO COUNTY- UPPER COLORADO RIVER VALLEY-LAS VEGAS VALLEY- SOUTHERN CLARK COUNTY- 423 AM PDT TUE SEP 13 2011 /423 AM MST TUE SEP 13 2011/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST ARIZONA...CALIFORNIA AND SOUTHERN NEVADA. .DAY ONE...TODAY AND TONIGHT A FLASH FLOOD WATCH IS IN EFFECT UNTIL MIDNIGHT FOR PORTIONS OF NORTHWEST ARIZONA...CALIFORNIA AND SOUTHERN NEVADA...INCLUDING THE FOLLOWING AREAS...IN NORTHWEST ARIZONA...LAKE HAVASU AND FORT MOHAVE... LAKE MEAD NATIONAL RECREATION AREA AND NORTHWEST DESERTS. IN CALIFORNIA...CADIZ BASIN...EASTERN MOJAVE DESERT...MORONGO BASIN AND SAN BERNARDINO COUNTY-UPPER COLORADO RIVER VALLEY. IN SOUTHERN NEVADA...LAKE MEAD NATIONAL RECREATION AREA...LAS VEGAS VALLEY AND SOUTHERN CLARK COUNTY. CONDITIONS COULD BE FAVORABLE FOR TRAINING OF THUNDERSTORMS OVER THE SAME AREA WHICH COULD PRODUCE RAINFALL RATES BETWEEN 1 AND 2 INCHES AN HOUR. AVOID AREAS ALREADY FLOODED ESPECIALLY IF THE WATER IS FLOWING FAST. DO NOT ATTEMPT TO CROSS FLOODED ROADWAYS OR NORMALLY DRY WASHES. TURN AROUND DON'T DROWN. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH THURSDAY AS AN AREA OF LOW PRESSURE SLOWLY MOVES EAST OVER THE MOJAVE DESERT AND SOUTHERN GREAT BASIN. BRIEF HEAVY RAIN AND SMALL HAIL WILL CONTINUE TO BE A THREAT. NO HAZARDOUS WEATHER IS EXPECTED FRIDAY THROUGH MONDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. HOWEVER... SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. AZZ001-CAZ519>523-NVZ014>019-140700- NORTHWEST PLATEAU-EASTERN SIERRA SLOPES-OWENS VALLEY- WHITE MOUNTAINS OF INYO COUNTY-DEATH VALLEY NATIONAL PARK- WESTERN MOJAVE DESERT-ESMERALDA AND CENTRAL NYE COUNTY- LINCOLN COUNTY-NORTHEAST CLARK COUNTY- WESTERN CLARK AND SOUTHERN NYE COUNTY-SHEEP RANGE- SPRING MOUNTAINS- 423 AM PDT TUE SEP 13 2011 /423 AM MST TUE SEP 13 2011/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST ARIZONA...CALIFORNIA AND SOUTHERN NEVADA. .DAY ONE...TODAY AND TONIGHT ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR TODAY AND TONIGHT. BRIEF HEAVY RAIN AND SMALL HAIL WILL OCCUR WITH THE STRONGEST THUNDERSTORMS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH THURSDAY AS AN AREA OF LOW PRESSURE SLOWLY MOVES EAST OVER THE MOJAVE DESERT AND SOUTHERN GREAT BASIN. BRIEF HEAVY RAIN AND SMALL HAIL WILL CONTINUE TO BE A THREAT. NO HAZARDOUS WEATHER IS EXPECTED FRIDAY THROUGH SUNDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. HOWEVER... SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE LAS VEGAS NV
406 AM PDT TUE SEP 13 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0105 AM HAIL HUALAPAI MOUNTAIN 35.10N 113.89W
09/13/2011 E0.50 INCH MOHAVE AZ TRAINED SPOTTER
A SPOTTER REPORTED HAIL UP TO DIME SIZE ON HUALAPAI
MOUNTAIN.
0215 AM LIGHTNING KINGMAN 35.21N 114.03W
09/13/2011 MOHAVE AZ TRAINED SPOTTER
A SPOTTER REPORTED LIGHTNING STRUCK A HOUSE AND SET IT ON
FIRE IN KINGMAN.
0311 AM TSTM WND GST NORTH LAS VEGAS AP 36.21N 115.20W
09/13/2011 M52.00 MPH CLARK NV ASOS
0316 AM HAIL 3 W NORTH LAS VEGAS 36.27N 115.20W
09/13/2011 E0.50 INCH CLARK NV NWS EMPLOYEE
AN OFF DUTY NWS EMPLOYEE REPORTED HAIL UP TO A HALF INCH
IN DIAMETER.
0332 AM HEAVY RAIN NORTH LAS VEGAS AP 36.21N 115.20W
09/13/2011 M0.52 INCH CLARK NV ASOS
THE ASOS AT THE NORTH LAS VEGAS AIRPORT MEASURED 0.52
INCH FROM A THUNDERSTORM IN 22 MINUTES. 0.26 INCH FELL IN
JUST 5 MINUTES.
&&
STACHELSKIPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
529 AM PDT TUE SEP 13 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0440 AM HEAVY RAIN SE TOPOCK 34.72N 114.47W
09/13/2011 M1.00 INCH MOHAVE AZ TRAINED SPOTTER
ONE INCH RECEIVED IN 30 TO 45 MINUTES.
&&
DMAKERPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
641 AM PDT TUE SEP 13 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0540 AM FLASH FLOOD 4 NNW TOPOCK 34.77N 114.50W
09/13/2011 MOHAVE AZ TRAINED SPOTTER
0.90 INCH OF RAIN IN AN HOUR OR LESS. MUD SLID OVER SOME
ROADS. THE EVENT TIME IS ESTIMATED.
&&
MORGANPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
834 AM PDT TUE SEP 13 2011
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0800 AM FLASH FLOOD 5 E DOWNTOWN LAS VEGAS 36.17N 115.06W
09/13/2011 CLARK NV TRAINED SPOTTER
A WEATHER SPOTTER REPORTED THAT 12 TO 14 INCHES OF WATER
WAS FLOWING ACROSS THE INTERSECTION OF NELLIS BOULEVARD
AND STEWART AVENUE. BOTH ROADS WERE COVERED WITH WATER A
QUARTER-MILE IN EACH DIRECTION.
0804 AM FLASH FLOOD 1 SE EAST LAS VEGAS 36.08N 115.03W
09/13/2011 CLARK NV PUBLIC
WATER WAS REPORTED FLOWING ACROSS THE INTERSECTION OF
BOULDER HIGHWAY AND RUSSEL ROAD AND SPILLING OVER INTO A
NEARBY FLOOD CHANNEL.
0809 AM FLASH FLOOD 4 NE DOWNTOWN LAS VEGAS 36.22N 115.09W
09/13/2011 CLARK NV FIRE DEPT/RESCUE
A SWIFT WATER RESCUE WAS REPORTED BY THE CLARK COUNTY
FIRE DEPARTMENT AT THE INTERSECTION OF CHEYENNE AVENUE
AND LAS VEGAS BOULEVARD.
&&
JAThe Santa Ana Mts radar (KSOX), 139 km away, was scanning. The volume nearest the first event began at 15:57 UTC.
1 lightning, 1 flash flood, 1 wildfire. Local standard time, as filed.
Lightning struck a power line at Highway 62 and Dorth Place.
A big rig got stuck in mud on Highway 62 at Ironage Road, closing the highway.
The John Fire burned 5,353 acres, but no structures. Two firefighters were injured during the fire.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2011Every state in 2011This day in weather historyWarnings in California, September 2011
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: 334121, 334122, 344570.