Southerly flow pulled moisture into the Desert Southwest, fueling thunderstorms over the Mojave Desert and the Sierra Nevada. Many storms produced flash flooding and/or 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.
Southerly flow pulled moisture into the Desert Southwest, fueling thunderstorms over the Mojave Desert and the Sierra Nevada. Many storms produced flash flooding and/or 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 Aug 1, 12:57 PM PST, 1 hour 9 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 157 PM PDT Wed Aug 1 2018 .SYNOPSIS... Another day or two of isolated to scattered showers and thunderstorms will be possible before rain chances begin to diminish moving into late week and into the weekend. Temperatures will drop a few degrees relative to the last several days with a drier pattern expected moving into next week. && .SHORT TERM...Tonight through Saturday night. Beginning to see some convection occuring over the Sierra Nevada Mountains this afternoon in addition to a few isolated cells southwest of Rachel and near Mount Trumbull. HREF/HRRR solutions diminish the activity over the Sierra Nevada by around 03-04Z but hangs on to isolated activity in Mohave county a little longer. PWAT values between 1.1 to 1.2 inches have been noted in RAP mesoanalysis in this area with increasing DCAPE values as you approach the Mohave/Clark County borders a bit farther west of the current convection. This will likely be the area of highest concern through the rest of the afternoon and evening due the better potential for strong outflow winds and heavy downpours. All activity subsides according to these hi-res solutions after 06Z, thus have decreased PoPs substantially at that point. An H5 shortwave from the Pacific Northwest will begin to push this stubborn ridge eastward Thursday which will begin the downtrend of precip chances moving into the weekend. During this evolution Thursday and Thursday evening, mid level convergence and modest upper level effects appear to phase, especially in the 12Z GFS20 which could be the trigger for the last significant round of precip Thursday afternoon and evening beginning first over the Sierra Nevada and traversing the northern periphery of the CWA including Esmeralda, Nye, and Lincoln Counties. As this feature shifts eastward moving into Friday morning, drier air will dominate the region and PoP chances dwindle moving into the weekend. && .LONG TERM...Sunday through Tuesday A short period of H5 zonal flow will occur throughout the southwest CONUS and a large, broad closed low approaches the western seaboard by Sunday night. It does appear in the 12Z long range models however that ridging will recover by mid-week and not back down to this Pacific low. There is still some model disagreement on the magnitude and orientation of the rebuilding ridge axis, with the GFS much more amplified whereas the Canadian/ECWMF are more broad. This may have some implications on the possibility for moisture to return to the area and thus PoP chances for the latter half of the week. At this time, opted for the Canadian/ECWMF solutions which are the drier options. Either way, the return of the ridge would likely kick high temperatures up again a few degrees ending the slightly cooler temperatures expected this weekend and early next week. && .AVIATION...For McCarran...South winds, with gusts up to 20 knots, will be likely this afternoon. The only complication to the wind forecast will be outflow from thunderstorms that develop south and west of the terminal. There is a slight chance of thunderstorms developing in the valley this afternoon. Without influence from convection, winds will remain south to southwesterly through the evening and gusts will wane after sunset. A drying pattern will limit thunderstorm activity Thursday and through at least Monday. Gusty south winds are anticipated Thursday with speeds between 10-20 knots. For the rest of southern Nevada, northwest Arizona and southeast California...Scattered to isolated thunderstorms possible in the Spring Mountains, Las Vegas valley, south Sierra, central Nevada, and northwest Arizona this afternoon and evening. Erratic, sudden, gusty outflows will be possible with thunderstorms. Best chances for thunderstorm development will be in KBIH today. Outside of thunderstorm influence, gusty south winds between 10-20 knots will be favored. Thursday, thunderstorms will be isolated to central Nevada, northwest Arizona and the Sierra. Elsewhere, dry conditions with gusty southerly winds, with speeds similar to Wednesday, are expected. SHORT TERM...Boucher AVIATION...Boothe LONG TERM...Boucher 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), 171 km away, was scanning. The volume nearest the first event began at 22:07 UTC.
2 flash flood, 1 thunderstorm wind, 1 flood. Local standard time, as filed.
Highway 168 was flooded and impassable just west of Westgard Pass.
Horseshoe Meadows Road was closed at Lubken Canyon Road due to mud slides.
Thunderstorm winds overturned two big rigs on I-15, injuring one person.
Water, rocks, and mud washed onto Highway 95, but the road remained passable.
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, August 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: 779111, 779112, 779113, 779114.