Southerly flow pulled moisture into the Mojave Desert, fueling scattered thunderstorms. Some storms produced severe weather and/or flash flooding.
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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 Mojave Desert, fueling scattered thunderstorms. Some storms produced severe weather and/or 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 14, 9:06 AM MST, 4 hours 59 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 906 AM PDT Tue Aug 14 2018 .SYNOPSIS...Isolated thunderstorms are possible again today over the southern Sierra and mountains of southern Nevada and northwest Arizona. Storm coverage will ramp up across Mohave County Wednesday and possibly spread farther north and west Thursday. Temperatures will remain a few degrees above normal today, then start to come down as thunderstorm chances increase. Decreasing thunderstorm chances and increasing temperatures will return Friday into the weekend. && .UPDATE...Expanded POPS this afternoon and evening to include the southern Clark County mountains and Sheep Range while keeping the POPs for the Spring Mountains. This based on the latest HRRR runs and other hi-res convective allowing models. Setup looks very similar to yesterday for Clark and Mohave Counties. No specific feature evident to provide additional lift so counting on surface heating for initiation. Lack of shear will mean most storms will likely weaken as they move into the lower valleys. More organized areas of convection should occur over central Nevada associated with weak trough lifting northward. However, storms still likely along the southern Sierra of Inyo County becoming more isolated in south central Nevada. Updated products are already out. Focus this afternoon will be for Wednesday and Thursday. && .PREV DISCUSSION...236 AM PDT Tue Aug 14 2018 .SHORT TERM...through Wednesday night. Early this morning, thicker clouds and a few weak radar returns were limited to Mohave and northern Lincoln counties. Expect another low grade monsoon day today as forcing which helped drive storms over the southern Great Basin Monday evening drifts away to the north, leaving no obvious feature to focus thunderstorm development today. The next feature to watch is the weak wave lifting north over Sonora this morning. This is forecast to drift around the southwest side of the ridge today and tonight, bringing a push of deeper moisture up the Colorado River valley tonight into Wednesday, which will lead to increasing thunderstorm chances especially for Mohave County. The wave may also help maintain storms through Wednesday night. Temperatures today should be similar to yesterday, with a cooling trend from Las Vegas southeastward on Wednesday as clouds and precip chances increase. .LONG TERM...Thursday through Tuesday. Thursday continues to look like the most active day across the area as moisture streams further north and west, reaching portions of the southern Great Basin and southern Inyo County. Along this line southward is where the highest chances for storms will be located. Activity could begin by mid to late morning on Thursday over the higher elevations of Clark and Mohave counties with a ramp up in coverage and intensity of storms during the afternoon and evening. Storms will have a general movement to the north to northeast with the ridge still centered to our east. The disturbance that moved into northern Arizona on Wednesday looks to drift away from the local area on Thursday but should still be close enough to provide some potential for intensification of storms. The environment will be conducive for flash flooding on Thursday as well as strong winds and hail. On Friday, a shortwave trough will progress eastward across the Great Basin as the ridge builds back westward over the Southwest U.S. which will provide some suppression for storms. However, with moisture and instability still in place, storms will continue to be a threat on Friday; primarily over Mohave County and the higher elevations of Clark County. The downward trend in storm activity will continue over the weekend as the ridge strengthens over the region. Temps will bottom out a few degrees below normal on Thursday but this cool down will be brief as high pressure facilitates a warming trend Friday into the weekend. && .AVIATION...For McCarran...Expect light winds this morning, becoming south southwest around 10 knots this afternoon and evening. Gusts of 15-20 knots will be possible this afternoon. Thunderstorm chances will increase Wednesday, especially in the Peach Springs corridor, with a chance of outflow winds affecting the terminal in the evening or overnight. For the rest of southern Nevada, northwest Arizona and southeast California...Thunderstorm chances this afternoon and evening will be over the mountains of Esmeralda, northern Inyo, northeast Lincoln, and eastern Mohave counties. A stray storm cannot be ruled out over the Clark County mountains as well. Away from storms, expect breezy southwesterly winds with gusts of 15-25 knots this afternoon. Thunderstorm chances will increase southeast of I-15 Wednesday, with the main threats being mountain obscuration, heavy rain, erratic gusty winds, and hail. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && UPDATE...Pierce SHORT TERM/AVIATION...Morgan LONG TERM...Guillet For more forecast information...see us on our webpage: http://weather.gov/lasvegas or follow us on Facebook and Twitter
The Las Vegas radar (KESX), 106 km away, was scanning. The volume nearest the first event began at 21:04 UTC.
5 flash flood. Local standard time, as filed.
DW Ranch Road was closed due to flooding.
Hackberry Road was closed from Highway 93 to Highway 66.
Antares Road was closed from Highway 66 to Pierce Ferry Road.
County Road 145 was closed due to flooding at Detrital Wash. A flood control gauge registered 3.5 feet of water.
Seventeen Mile Road was closed from Highway 93 to Signal Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2018Every state in 2018This day in weather historyWarnings in Arizona, 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: 779142, 779143, 779144, 779145, 779146.