Monsoon moisture slowly seeped into the region under the big dome of high pressure which was causing record-breaking temperatures, fueling isolated to scattered thunderstorms. As the moisture increased, the main thunderstorm impact transitioned from high winds to flash flooding.
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.
Monsoon moisture slowly seeped into the region under the big dome of high pressure which was causing record-breaking temperatures, fueling isolated to scattered thunderstorms. As the moisture increased, the main thunderstorm impact transitioned from high winds to 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 10, 2:10 PM MST, 5 hours 30 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 210 PM PDT Sat Jul 10 2021 .SYNOPSIS...Major heat wave will peak across the region over the weekend with long standing and all-time record high temperatures being challenged or exceeded in some areas. Isolated thunderstorms will continue to be possible in the afternoon and evening hours, but mainly in the higher terrain and in northwest Arizona. Heat will gradually moderate next week as high pressure weakens and deeper monsoonal moisture moves into eastern areas. && .DISCUSSION...Through next Saturday. Through Tuesday...Intense high center with H5 heights greater than 597 dm will stay positioned over the southern Great Basin and Mojave Desert. Extremely dangerous temperatures will continue to occur. The heat product may need to be extended out one more day to Tuesday for our western zones but we can cross that bridge either tonight or tomorrow. Modest monsoon moisture is in place across parts of southern Clark, southern Mohave and eastern San Bernardino Counties. This moisture will generally remain in place or get nudged slightly further west and north through Tuesday; generally staying along and southeast of I-15. Latest HRRR run continues to indicate isolated thunderstorms in southern Mohave County into this evening, working as far west as around Kingman before starting to weaken. Outflow easterly winds from the storms have the potential of making it into the Colorado River Valley between Lake Mohave and Lake Havasu. Winds speeds do not look that intense maybe gusts up to 30 mph. As the moisture seeps northward the threat of isolated thunderstorms increases slightly Sunday into Tuesday. Any storms along and southeast of I-15 should be wet, while elsewhere isolated dry thunderstorms are possible over south central Nevada and Inyo County. Will continue to monitor the need for any fire weather headlines regarding dry lightning. Wednesday and Beyond: Trough along the West Coast will allow H5 heights to retreat slightly during the period as the high center shifts east toward the Four Corners region by next Saturday. This will bring an end to the extreme temperatures as values return closer to our mid-July normals. Southwest flow associated with the trough will spread drier air in from the west limiting any chance for showers and thunderstorms to Mohave County Thursday-Saturday. && .CLIMATE...Listed below are a few climate locations showing both the record high maximum and high minimum temperature for each location and the year the record was last set for Saturday, Sunday and Monday. LOCATION SAT-JULY 10 SUN-JULY 11 MON-JULY 12 (HIGH MAX) Record(year) Record(year) Record(year) Las Vegas NV 114(2012) 116(1959) 114(2003) Bishop CA 110(2002) 107(2020) 108(2020) Barstow CA 115(1961) 115(2003) 115(2020) Needles CA 121(2003) 120(2020) 124(1925) Kingman AZ 111(2003) 110(1961) 111(2020) Desert Rock NV 110(2002) 110(2012) 111(2020) Death Valley CA 134(1913) 129(1913) 130(1913) LOCATION SAT-JULY 10 SUN-JULY 11 MON-JULY 12 (HIGH MIN) Record(year) Record(year) Record(year) Las Vegas NV 89(2002) 91(2012) 94(2020) Bishop CA 71(1985) 70(2013) 69(1990) Barstow CA 84(2013) 85(2002) 87(2012) Needles CA 92(2002) 94(2012) 92(2019) Kingman AZ 79(1913) 81(1906) 83(1925) Desert Rock NV 81(1981) 81(1996) 81(2003) Death Valley CA 100(1924) 105(1920) 107(2012) && .AVIATION...For McCarran...Easterly or light and variable wind expected into early evening. Speeds should stay at 8 kts or less. After 02Z, typical south-southwesterly wind will develop and continue overnight. Light easterly wind will develop again Sunday with speeds 8 kts or less. Expecting more storm development over the mountains west of the valley tomorrow. Outflow from the decaying storms could impact the terminal late in the afternoon. Confidence to low to include the forecast at this point. SCT-BKN150 during the period. Extreme temperatures are expected through the weekend, with temperatures reaching 100 degrees each morning by 9-10 AM and falling below in the 12-2 AM time frame. High temperatures will be near 116 today and Sunday. For the rest of southern Nevada, northwest Arizona, and southeast California...Easterly outflow winds up to 25 kts could impact KEED and KIFP early this evening as storms weaken to the east over Mohave County. Gusty outflow winds from storms along the southern Sierra crest may also impact KBIH with gusty westerly winds. Elsewhere, isolated storms will dissipate this evening leaving behind partly to mostly cloudy skies and typical nighttime down valley winds. Similar conditions are forecast tomorrow with greatest thunderstorm threat being over Mohave County and the southern Sierra crest. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && DISCUSSION...Pierce CLIMATE...Peters 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), 94 km away, was scanning. The volume nearest the first event began at 02:37 UTC.
5 flash flood, 4 thunderstorm wind. Local standard time, as filed.
A 20X14 foot piece of roof was blown off a hay barn.
Mountain View Road was closed between Crystal Drive and Desert Greens Drive.
A tree was also blown down at the Mohave County Fairgrounds. This unusually long duration severe wind event was believed to be associated with a wake low.
Hackberry Road was closed from Main Street to Highway 66 due to flooding from runoff from storms which occurred hours earlier.
Antares Road was closed from Highway 66 to Pierce Ferry Road due to flooding from runoff from storms which occurred hours earlier.
Thunderstorm winds blew down numerous trees, some of which blocked roads and some of which fell on power lines. Trampolines were also blown into roads.
Flooding and debris covered Pierce Ferry Road from Highway 93 to mile marker 4.
Flooding and debris covered several roads in the Hualapai Mountains.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2021Every state in 2021This day in weather historyWarnings in Arizona, 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: 974588, 974597, 974599, 974601, 974602, 974604, 974606, 974608, 974610.