A more substantial push of monsoon moisture helped trigger widespread thunderstorms across the Mojave Desert and southern Great Basin. Many storms produced severe weather and 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.
A more substantial push of monsoon moisture helped trigger widespread thunderstorms across the Mojave Desert and southern Great Basin. Many storms produced severe weather and 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 Jul 11, 10:57 AM PST, 3 hours 18 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 1157 AM PDT Wed Jul 11 2018 .SYNOPSIS...Plentiful moisture will remain in place through the upcoming weekend resulting in daily chances for showers and thunderstorms. Best chances for storm activity today will be across southern Mohave and San Bernardino counties as well as across Lincoln County. For the coming days the best chances for storms will be across the high terrain with the lower Mojave Desert beginning to gradually dry and warm late this week into the weekend. Heavy rainfall and gusty winds will be possible with storms. && .UPDATE...Flash Flood Watch has been issued until 11 pm this evening for parts of southern Nevada, southeast California and southern Mohave county. Air mass rapidly destabilized with thunderstorms firing over the higher terrain of the watch area. Generally looking a rainfall rates of 1-2 inches, but can not rule out localized rates of 2-3 inches. && .PREV UPDATE...922 AM PDT Wed Jul 11 2018 Radar has been detecting light rain showers developing, then quickly dissipating in the lower Colorado River Valley near Lake Havasu City, northern Clark and northern Mohave Counties the past two hours. Daybreak started off with extensive cloud cover over Clark, Mohave and San Bernardino Counties. Satellite starting to show some breaks developing within the cloud shield. Within the cloud shield we will be keying on differential heating boundaries as region for convective initiation. With less cloud cover across western San Bernardino, Inyo, Esmeralda, Nye and Lincoln counties am expecting convective initiation sooner. Localized heavy rain fall concern across the Mojave Desert with precipitable water values between 1- 1.5 inches. Can not rule out gusty winds as well, especially if storms become organized into lines or multi-cellular clusters. See no lightning yet so will do a minor update to mention showers as the primary weather with a slight chance of thunderstorms for the rest of this morning. && .PREV DISCUSSION...431 AM PDT Wed Jul 11 2018 .DISCUSSION...Today through Tuesday. Now...Main area of concern at this hour is convection drifting west/southwest from near Pahrump, across southern Death Valley NP into northwest San Bernardino County. This activity is being forced by a weak vorticity lobe and upper level divergence associated with the easterly wave/inverted trough that has been impacting the area for the last couple days now. Expect this activity to continue to push southwest out of the area through mid-morning. Elsewhere (mainly south of I-15) low clouds have been enhancing and a few weak echos noted on the backside of the vorticity lobe. This activity may develop further through the morning hours, though there is some question about the intensity if the clouds hang around a limit surface heating. Today/Tonight...At least weak instability is expected across the entire forecast area today. In general, models agree that the strongest instability (CAPE of 1000 J/kg+) will develop across eastern San Bernardino and southern Mohave counties - this is the area where low clouds are currently enhancing which leads to some increased uncertainty. If this area can get going then this will be the main area of concern through mid-late afternoon. Elsewhere convection will rely on surface heating and terrain to drive development. Individual cells today will generally move west around 5-10 MPH. There are hints that enough convection across the central Nevada and southwest Utah could result in a strong enough cold pool to organize one or more MCSs. With modest S/SW inflow layer this could lead to a MCS that propagate south/SW towards Clark County by this evening. However, I would like to see a stronger inflow, indications of more cohesive cold pool development, and slightly earlier timing for me to forecast this activity to make it all the way to Vegas. Right now, I'd guess that any MCSs would fall apart before reaching this far south. We will have to monitor this through the day. Most activity should die off after sunset. However, some weak convection could continue during the overnight hours courtesy continued influence of weak vorticity lobes pushing through the area. Thursday/Thursday Night...Overall convective setup on Thursday appears similar to today with a slight northward shift. This could result in slightly more favorable conditions for the MCS scenario outlined above. In general through, convection will be diurnally driven. Friday and beyond...High pressure begins to shift overhead and broaden through the period. Moisture will remain in place, but a lack of significant forcing and the shifting high will result in a downward trend in convection over the lower Mojave Desert and diurnal terrain-driven storms to the north. Temperatures will also rise, though at this time it appears that temperatures will remain below excessive heat levels. It will continue to feel somewhat muggy by desert standards into next week. && .AVIATION...For McCarran...Light and variable winds this morning will turn easterly mid to late this morning; remaining around 10 knots or less. Going into the afternoon a southerly shift is expected between 21z-23z and an increase to around 10-12 knots. Isolated showers and storms are possible again this afternoon around the valley which could produce gusty, erratic winds moving through the terminal late this afternoon and evening. Confidence is low on which direction these gusts would come from but current model trends lean toward south to southeasterly gusts, similar to what was seen yesterday. SCT to BKN mid/high clouds will persist through the period; remaining at or above 10k feet. For the rest of southern Nevada, northwest Arizona and southeast California...Isolated showers with a few lightning strikes have lingered into early this morning across portions of the area. Coverage of showers and storms will increase this afternoon across the Mojave Desert followed by increasing potential over the Arizona Strip and the southern Great Basin later in the afternoon and evening hours. With storms that develop, erratic, gusty winds and locally heavy downpours will be likely along with periods of lower cigs between 6k-9k feet. There is slightly higher confidence in activity in the vicinity of the Colorado River Valley terminals and KDAG where VCTS has been included. Outside of storm activity, winds will favor the southerly direction between 10-15 knots with intermittent gusts to around 20 knots possible this afternoon into this evening before winds decrease overnight. && .SPOTTER INFORMATION STATEMENT...There will be chances for thunderstorms each day through next week. Spotter activation may be needed at times. Regardless of activation, spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && UPDATE...Pierce DISCUSSION...Wolcott AVIATION.....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), 84 km away, was scanning. The volume nearest the first event began at 22:14 UTC.
15 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Washes overflowed and flooded roads west northwest of Needles.
Flood waters came down from Dante's View and crossed Badwater Road.
Goffs Road was flooded between I-40 and Highway 95.
Major flooding in Twentynine Palms closed Adobe Road between Civic Center Drive and Gorgonio, and also closed the gates at Ocotillo and Split Rock.
Cars were stuck in deep flooding on Highway 62 at mile marker 42.
Eureka Valley Road was flooded.
Water flowed over a road at Havasu Landing on the Chemeheuvi reservation.
Highway 95 was closed just north of I-40 due to mud, rocks, and trees covering the road.
Flash flooding closed Goffs Road.
The intersection of Highways 127 and 190 was flooded and closed.
Several OHV roads at Ancient Bristlecone Pine Forest were flooded and had sinkholes, and a stretch of Highway 168 was closed.
The intersection of Nipton Road and Ivanpah Road was washed out.
Cima Road was covered in mud near I-15, and one vehicle was stuck in flood waters.
Thunderstorm winds derailed 15 train cars, blocking Highway 95.
Highway 95 was covered with mud and closed.
Racetrack Valley Road was flooded.
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: 774018, 774020, 774019, 774021, 774022, 774023, 774024, 774025, 774026, 774027, 774030, 774032, 774033, 774034, 774036, 774037.