A strong push of monsoon moisture plus low pressure moving in from the west triggered an outbreak of thunderstorms over the Mojave Desert with a few thunderstorms over the southern Great Basin. Several storms produced flash flooding and severe weather.
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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.
A strong push of monsoon moisture plus low pressure moving in from the west triggered an outbreak of thunderstorms over the Mojave Desert with a few thunderstorms over the southern Great Basin. Several 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 7, 2:20 PM PST, 2 hours 59 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 320 PM PDT Thu Sep 7 2017 .SYNOPSIS...Moisture is expected to increase Friday through Sunday leading to more widespread showers and thunderstorms over portions of the southern Great Basin and Mojave Desert. Temperatures will cool to below normal readings Friday and Saturday with the additional cloud cover. && .SHORT TERM...tonight through Sunday. Moisture and instability over the eastern half of the forecast area has led to scattered showers and thunderstorms over Mohave, Clark and San Bernardino Counties this afternoon. The strongest storms are occurring over portions of eastern San Beranrdino and Clark counties where strong wind gusts have been an issue. DCAPES are generally around 1700 J/KG and we have seen several microbursts in the area. With ongoing outflow boundaries we may see storms continue through the evening before dissipating late. Upper low off the central California coast will move inland overnight and the associated trough will help pull low level monsoonal moisture northward early Friday. This moisture is expected to increase through the afternoon and into Saturday. Dynamics associated with low combined with increasing instability will lead to more widespread thunderstorms over Mohave, Clark, Lincoln, southern Nye, and eastern San Bernardino Counties Friday and Saturday. A sharp moisture/instability boundary stretching from roughly western Lincoln down through eastern San Bernardino County should keep things dry to the west, but storms along this boundary could become more organized. With the increased moisture and potential for training storms, heavy rain and long duration rainfall could be an issue. Have gone ahead and issued a flash flood watch for those aforementioned areas starting mid Friday morning and continuing into Monday morning. Moisture will remain on Sunday, but the upper low that moved inland over central California will retrograde and the moisture boundary is expected to shift further west. This could bring more of the heavy rain and thunderstorms to western San Bernardino and Inyo Counties Sunday. At this time will not issue any statements for those areas, but as we get close a Watch may be needed. .LONG TERM...Monday through Thursday. Lingering chances for thunderstorms, though lower than Saturday, will remain over much of the forecast area Sunday as moisture wraps around the closed low off the southern California Coast. Although moisture decreases, there will be broad diffluence over much of the forecast area and more surface heating to support thunderstorm development. There is good agreement among the GFS and ECMWF that a drier southwest flow will spread over the region Monday through Wednesday as the closed low slowly lifts toward central California then moves inland. The ECMWF depicts a deep broad trough diving out of the Pacific Northwest that looks like will scour all moisture out of the region by Thursday along with a noteworthy cooling trend. If this plays out, it will be the end of monsoon season about on schedule with the transition to a fall pattern as troughs drop down from the northwest. && .AVIATION...For McCarran...Afternoon thunderstorms will subside and gusty south winds will subside and favor the usual southwest overnight. By late tomorrow morning, southeast winds will kick in, bringing a push of monsoon moisture and thunderstorms to the region. Training thunderstorms will be possible much of the day into overnight, capable of producing gusty winds and very heavy rain. Ceilings may come down to below 10 kft under thunderstorms. For the rest of southern Nevada, northwest Arizona and southeast California...Increasing moisture will bring increasing thunderstorm chances and lowering ceilings across much of the region, especially along the Colorado River Valley. Storms are likely to be more widespread by the evening, with gusty winds and heavy rain the main threats. Ceilings look to fall to or under 10 kft under thunderstorms. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && SHORT TERM...Gorelow LONG TERM....Adair AVIATION.....Steele For more forecast information...see us on our webpage: http://weather.gov/lasvegas or follow us on Facebook and Twitter
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
551 PM PDT THU SEP 07 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0431 PM FLASH FLOOD 14 ESE TWENTYNINE PALMS 34.08N 115.56W
09/07/2017 SAN BERNARDINO CA LAW ENFORCEMENT
CHP REPORTED THAT HIGHWAY 62 WAS FLOODED AND IMPASSABLE
AT MILE MARKER 62.
&&
MORGANThe Cedar City radar (KICX), 209 km away, was scanning. The volume nearest the first event began at 01:20 UTC.
3 flash flood, 1 funnel cloud. Local standard time, as filed.
A 200-300 yard stretch of Highway 318 was flooded at Hiko.
Nipton Road was closed to Highway 95 due to flooding. This event continued into California.
Cottonwood Cove Road was closed due to flooding.
A funnel cloud was photographed between Searchlight and Nelson Landing.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2017Every state in 2017This day in weather historyWarnings in Nevada, September 2017
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: 716614, 716615, 716616, 716617.