Thunderstorms on the eastern slopes of the southern Sierra led to large mud slides two days in a row.
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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.
Thunderstorms on the eastern slopes of the southern Sierra led to large mud slides two days in a row.
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 Jul 22, 9:00 AM PST, 4 hours 41 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 1000 AM PDT Sun Jul 22 2018 .SYNOPSIS...Moist air will remain over the region through Monday, providing fuel for afternoon and evening thunderstorms, especially over the higher terrain north of Las Vegas. High pressure will bring very hot temperatures to the area Tuesday through Thursday, along with less thunderstorm coverage. && .UPDATE...A mostly clear sky was allowing good surface heating over the forecast area except central and northern Lincoln County where extensive clouds and scattered showers were still occurring with the lingering circulation that moved up late Saturday. The the most favorable spots for afternoon thunderstorms appear to be the Spring Mountains, the southern Sierra and Esmeralda/central Nye counties. The 12Z Las Vegas sounding indicates there is still plenty of moisture below 500 mb. A light westerly flow is evident on the sounding below 500 mb which backs to southerly above that level. So, storms that develop will move slowly to the east-northeast. This will leave the northwest part of the Las Vegas Valley susceptible to storms that develop over the Spring Mountains. The latest HRRR indicates central Nevada convection will propagate southward late this afternoon and evening. This will need to watched for the potential to move into Clark County this evening, but the HRRR indicates convection will dissipate before reaching the northern border. This supports the going forecast trends and no immediate changes are needed. -Adair && .PREV DISCUSSION...224 AM PDT .SHORT TERM...through Tuesday night. Mesoscale convective vortex which overachieved yesterday was over Lincoln County this morning, with a tail of clouds extending south over the Overton Arm. Areas to its south were under descending air, bringing clear skies early this morning. These areas were also significantly cooler than 24 hours ago, which will inhibit thunderstorm development. The best chances for today and Monday should be from Inyo County through Lincoln County, with lesser chances over the Mojave Preserve, the Clark County mountains, and the higher terrain of Mohave County. The focus will shift to temperatures Monday and Tuesday as the long advertised heat wave kicks in. Excessive Heat Warning beginning Tuesday still looks good and will not make any changes. .LONG TERM...Wednesday through Sunday. There is little change in overall thinking with high confidence that strong high pressure over the area will lead to excessive heat for much of next week. Still looking for temperatures to run about 10 degrees above normal for most areas which will put places like Las Vegas in the 111-115 degree range, the Colorado River Valley 116- 121, and Death Valley seeing highs 123-127. Extended numerical guidance shows some slight cooling occuring by next Friday and Saturday, but with the high not moving much not really sure how much temperatures will actually cool. With the strong high over the area, this will keep any significant moisture from working into the area. It does look like there will be enough residual moisture around leading to isolated higher terrain storms, but at this time nothing widespread. However, this is monsoon season and thing can change rather quickly. && .AVIATION...For McCarran...Looks like a down day for convection as storms should miss the Las Vegas Valley. It does look like isolated storms will be possible over the Spring Mountains this afternoon, but they should drift off to the north. Otherwise look for mainly terrain winds with speeds less than 8 kts. Few clouds around 12k feet between 18z-02z. For the rest of southern Nevada, northwest Arizona and southeast California...Isolated storms expected to develop over the mountains this afternoon. Except for influences from storms, winds will be light through today. Clouds will generally be few-sct 12k feet or above. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && SHORT TERM...Morgan LONG TERM/AVIATION...Gorelow For more forecast information...see us on our webpage: http://weather.gov/lasvegas or follow us on Facebook and Twitter
The San Joaquin Valley radar (KHNX), 136 km away, was scanning. The volume nearest the first event began at 21:39 UTC.
2 flash flood. Local standard time, as filed.
Several large mud slides covered and closed Highway 168 near Aspendell, with about 50 people stranded. The highway was closed for several days.
More mud slides occurred across Highway 168 near Aspendell, essentially erasing progress made by crews cleaning up from the previous day's event.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2018Every state in 2018This day in weather historyWarnings in California, July 2018
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: 774111, 774112.