After a brief break, another push of monsoon moisture fueled another round of thunderstorms over the Mojave Desert. Some storms produced 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.
After a brief break, another push of monsoon moisture fueled another round of thunderstorms over the Mojave Desert. Some storms produced 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 29, 2:40 PM MST, 1 hour 50 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 240 PM PDT Thu Jul 29 2021 .SYNOPSIS...Another episode of high monsoonal moisture is expected through the weekend which will lead to an increased threat of flash flooding and strong outflow winds. A Flash Flood Watch has been issued for much of the region through Sunday morning. Beginning late Sunday, drier conditions are expected to move in and result in several days of drier and warmer conditions through next week. && .SHORT TERM...Today through Sunday. The focus of the near and short term forecast is the return of anomalous monsoonal moisture and the prospects for flash flooding through the weekend. Beginning today, low level moisture is expected to begin spreading into the region from the south. This is well evident on GOES17 WV imagery and already this afternoon, several areas of high terrain convection have begun. The 12Z KLAS sounding (and continued through 20Z in the RAP) indicated a stout inverted V sounding paired with increasing moisture. While the better upper level support arrives tomorrow, today's convection will be mostly rooted on high terrain areas and push northwestward with the mean flow. That being said, today will likely be the best opportunity for downburst wind potential as the column continues to moisten but mid and low level dry air still exists. Especially if this convection intensifies on high terrain and downdrafts fall through much drier low desert areas. Of course, as convection continues, outflows will largely steer the potential for organized convection, but a lack of effective shear today should help to keep that from growing too far upscale. Best potential for impacts to the Las Vegas Valley would come in the way of wind most likely, either by convection that initiates over the Black Mountain area or inheriting outflow winds from convection in Arizona or southwest Utah...or both. Moving to Friday and over the weekend, PWATs begin to exceed 200% of normal, which is seasonally our period of highest moisture climatologically. At the same time, inverted troughing from Mexico slides northward adding additional upper level lifting to graduate flash flood risk from isolated to more widespread, hence the decision to issue a watch. The track of the trough will enhance lifting across much of the area but especially the high terrain mountain areas of Clark and Inyo counties. 12Z HREF is really highlighting enhanced upslope lifting due to this trough passage and this is also supported in the 12Z GFS. If this comes to fruition, the flash flood and damaging wind threat could be of particular concern for these areas. Yet another disturbance is progged to follow northward, but this time from the Pacific Saturday, leading to a similar concern Saturday and Saturday night. PWAT values don't change much afternoon/evening convection will again produce similar threats. The highest impact areas are less certain Saturday but any location that sees significant impacts Friday will be highly vulnerable for further or exacerbated impacts Saturday. Sunday is a little less certain as there are some indications that this second shortwave lingers across the Great Basin, pushes farther north into Idaho, or northeast and accelerates regional drying. There may be a need to extend our Flash Flood Watch for part of the area into Sunday but did not have the confidence yet in this coming to fruition nor the areas that would be affected. All this to say that the preparations should be taken to prepare for flash flooding impacts and strong, possibly damaging outflow winds through the weekend. Ensuring you are capable of receiving Flash Flood Warnings and other weather alerts is key and staying weather aware will be important. && .LONG TERM....Next Week. A chance in pattern over the long term looks to be on the horizon as a reprieve from anomalous moisture takes shape in the long range ensembles. PWAT anomalies actually swing to below average, in both the EC and GEFS by early next week with high pressure solidly in place over southern California. This would allow for temperatures to rise back to around normal values and give a break to the region that has seen an extended period of monsoonal thunderstorms. However, moisture gradually increases late week and by next weekend, precip chances may return to the CWA. && .AVIATION...For McCarran...Scattered thunderstorms are expected to increase across the area this afternoon and evening. CIGS will drop to around 8kft in and near any storms. The best chance for storms impacting the terminal is between 01 and 07z Friday. Erratic winds can be expected near any storms. After 09Z, storms will decrease in intensity. When storms are not impacting the terminal, expect light and diurnal winds with CIGS aoa 15kft. Thunderstorms are possible through Sunday with the greatest chance Friday and Saturday. For the rest of southern Nevada, northwest Arizona and southeast California...Scattered thunderstorms will impact most terminals as storms become more widespread through the evening into the overnight hours. Winds will be erratic with CIGS around 8kft near any thunderstorms. When storms are not around terminals, expect typical diurnal winds and periods of CIGS around 15kft. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant flash flooding impacts or wind gust/damage reports over the weekend. && DISCUSSIONS...TB3 AVIATION...Berc 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), 158 km away, was scanning. The volume nearest the first event began at 23:32 UTC.
3 flash flood. Local standard time, as filed.
Pump Station Road was closed from Highway 93 to Back Road due to flooding.
Water and debris flowed over Stockton Hill Road.
Antares Road was closed after flooding carved a foot deep rut into the road.
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: 976201, 976202, 976203.