A big push of monsoon moisture led to ten days of scattered thunderstorms over the Mojave Desert and southern Great Basin. Many storms produced flash flooding and/or high winds.
Every event with a place to put it. Tap one for its entry below.
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 big push of monsoon moisture led to ten days of scattered thunderstorms over the Mojave Desert and southern Great Basin. Many storms produced flash flooding and/or high winds. Events in this episode are continued in the July 22-26 Thunderstorms episode.
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 18, 3:36 AM PST, 8 hours 54 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 436 AM PDT Sun Jul 18 2021 .SYNOPSIS...Showers and few thunderstorms are possible this morning with additional thunderstorms developing across much of the area on later today. There will be a chance of showers and thunderstorms pretty much every day of the week with better chances mid-late in the week. With the higher humidity levels, temperatures are expected to be at or below normal most days. && .SHORT TERM...Through Tuesday night. Since coming on shift late Saturday evening, areal coverage of showers has been expanding over central Mohave, far southern Clark and San Bernardino Counties. Lack of instability will limit thunderstorms but won't be surprised to see a few cloud flashes or cloud-to-ground discharges through sunrise. Weak upper level disturbance moving northwestward will allow the area of showers and a few embedded thunderstorms to continue to develop and shift into Inyo, Nye and the rest of Clark County through the rest of this morning. As the feature continues northwest it will help in the development of some showers and thunderstorms across northern Inyo and Esmeralda Counties this afternoon. For the remainder of the area. HREF indicates highest probability of stronger storms today will be over Clark, Lincoln and Mohave Counties. As moisture continues to advect northward into the area locally heavy rain a concern today for the higher terrain in the above mentioned counties. The Mahogany burn area in the Spring Mountains from 2020 will need to be monitored today for runoff concerns. Hi-res guidance is showing a lower probability for heavy rain around the Flag burn area in the Hualapai Mountains today but we will continue to closely monitor that area after yesterday. Storms look capable of easily producing wind gusts of 35 to 50 mph today as well. More defined feature presently moving north near the Baja Spur is progged to move north along the southern California Coast tonight. Modest jet streak of 50-60 kts moving over the area could contribute into another nocturnal round of scattered showers and isolated thunderstorms. As this feature continues northward along the central California coast Monday, HREF indicated highest probability of stronger storms across northern Inyo, Esmeralda and central Nevada Monday afternoon. Locally heavy rain will occur over the higher terrain and again gusty winds of 35 to 50 mph possible. Heavy rain threat looks to increase on Monday for the Flag burn area. No feature evident in models circulating around the high center at this time for Tuesday. This could be the down day as global models and NBM PoPs showing best chances across Mohave County with isolated showers and thunderstorms possible over the higher terrain of southern Nevada and southeast California. Combination of additional clouds and shower/thunderstorm chances, temperatures will be at or slightly below normal. Outside of thunderstorms no significant winds expected. .LONG TERM...Wednesday through Saturday. High pressure centered east of the area will keep a favorable monsoonal flow pattern through the extended period. Late in the week, ensembles have been consistently forecasting an easterly wave undercutting the ridge as it moves from southern New Mexico on Friday westward to southern California on Saturday. The setup will allow westward propagating disturbances or boundaries to move across and tap a deeper pool of moisture over southwestern Arizona and then inject it into our area. The amount of concern regarding potential impacts could be high if any of the disturbances are dynamically robust, providing instability and a lifting mechanism to go along with the moisture. We will likely not see any of these features too far in advance so keep an active ear and eye to the weather this week. && .FIRE WEATHER...Shower and thunderstorm activity moving into the area early today will bring the threat of lightning to a dry lower atmosphere. Given the precarious state of fuels in the Sierra this will create the potential for lighting to start fires in an environment where rapid spread is possible. Luckily, the atmosphere moistens up relatively quickly. By Monday morning, the threat of dry thunderstorms diminishes to the point where a Red Flag Warning is no longer needed. It should be noted though that thunderstorms remain in the forecast through the period and have the potential to start wildland fires. && .AVIATION...For McCarran...Moderate impacts possible today due to the potential for vicinity thunderstorms and potentially strong outflow winds that could impact the terminal this afternoon. Passing showers this morning will keep southeast winds breezy for the first hour or so of the TAF then light winds expected until the early afternoon. Initial TSRA development is expected over the Spring Mountains but developing eastward and pushing outflow east into the valley after. Best timing for this looks to be aoa 21Z give or take an hour or so. Amendments may be needed and AWW issuances are not out of the question either depending on the strength of the storms and whether a direct impact to the terminal occurs. Most activity should be concluded after 02Z and returning to typical overnight winds late tonight. For the rest of southern Nevada, northwest Arizona and southeast California...Minor to moderate impacts are possible for several TAF sites today due to isolated TSRA producing outflow winds across the Great Basin. Most simulations put the bulk of the activity north of KEED/KIFP but opted to include VCTS anyway given the very favorable moisture today. Expecting impacts in the LV Valley this afternoon as well as KDAG/KBIH this afternoon as well resulting in periods of TSRA and gusty outflow winds. Activity is expected to wane after 05- 06Z tonight returning most locations back to typical wind patterns. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && SHORT TERM...Pierce LONG TERM...Salmen FIRE WEATHER...Lericos AVIATION...TB3 For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter
The Las Vegas radar (KESX), 111 km away, was scanning. The volume nearest the first event began at 20:31 UTC.
5 flash flood, 1 thunderstorm wind. Local standard time, as filed.
Flash flooding in Cold Creek washed out the shoulders of some roads.
One foot of water flowed over the intersection of Boulder Highway and Sunset.
Hidden Valley Road was closed at the Muddy River crossing due to flooding.
Water flowed over Interstate 15 near Moapa, causing traffic to be diverted.
Thunderstorm winds grounded a houseboat just outside Callville Bay, necessitating a rescue.
The Overton Wash flooded Highway 169 about two feet deep.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2021Every state in 2021This day in weather historyWarnings in Nevada, July 2021
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: 975429, 975431, 975433, 975434, 975435, 975439.