A push of monsoon moisture fueled an outbreak of thunderstorms with 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 push of monsoon moisture fueled an outbreak of thunderstorms with 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 Aug 1, 5:52 PM MST, 17 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 552 PM PDT Tue Aug 1 2017 .SYNOPSIS...Monsoon moisture will continue to push in from the south, bringing chances for thunderstorms through the week. Temperatures will remain near normal, except in areas where thunderstorms occur. Humid conditions will also persist, most notably near and southeast of Interstate 15. && .UPDATE...Quick update was made around 5pm this evening to significantly boost precipitation chances for southern Mohave County across Lake Havasu City. Now at 550pm, storms are just about to roll through Lake Havasu City with a Severe Thunderstorm Warning in effect for that area. Other tweaks were made across the southern portions of Death Valley and Inyo County where storm activity was ongoing. Storms are expected to decrease in coverage with the loss of daytime heating over the next 2 hours. Will continue to monitor and update as needed through the evening. -Wolcott- && .PREV DISCUSSION... 220 PM PDT Tue Aug 1 2017 .DISCUSSION...Showers and storms were a bit more numerous this afternoon than 24 hours ago, but none were getting particularly strong as of 2 PM. As noted by previous shifts, the main concern for this period appears to be flash flooding Wednesday. Analyses showed higher precipitable water lurking south of our area, and models show values as high as 2 inches being pulled north and west tomorrow, perhaps reaching as far as Needles and Twentynine Palms. Discussed the possibility of a Flash Flood Watch for portions of San Bernardino County, but eventually decided against it due to forecast storm motions being a little too fast to favor flash flooding. With that said, any storms which anchor onto terrain or train across the same location will likely produce flash flooding, but the coverage is expected to be too low to justify a Watch. Precip chances will remain elevated on Thursday, then the forecast becomes more uncertain from Friday onward. The models are disagreeing on how to handle a weak trough approaching the West Coast, which may or may not bring some drying southwest flow to our area. The GFS is more aggressive with the drying than the ECMWF, which has been the case for a few days now. Tried to paint a compromise in the grids, showing precip chances across the north as a nod to the GFS and also across the east as a nod to the ECMWF, with dry conditions for most of San Bernardino County and nearby areas. In general, temperatures should be within a few degrees of normal through the period, except for spots where thunderstorms occur early in the day. && .FIRE WEATHER...The atmosphere will be fairly moist and unstable through the week, leading to isolated to scattered thunderstorms which will have the potential to produce heavy rain. High pressure developing over northern Nevada may suppress thunderstorm activity over Lincoln, Nye and Esmeralda Counties for much of the upcoming week. && .HYDROLOGY...Creeks, streams and rivers in northern Inyo County have shown decreasing flows over the last couple of days. However, some road closures continue in the area. Bishop Creek Bypass and Big Pine Creek Bypass continue to be utilized to minimize flows through Bishop and Big Pine. Increasing moisture will bring increasing thunderstorm chances, which could produce additional runoff that could rapidly increase flows beginning on Wednesday. Remember, never drive through flooded roadways or around barricades. Also, pastureland or farmland adjacent to creeks, streams or rivers could experience areas of standing water. && .AVIATION...For McCarran...Light winds favoring diurnal patterns expected through early afternoon Wednesday. There is a small chance southerly outflow from thunderstorms near Laughlin could impact the airfield this evening (between 3-6z) but confidence is low and speeds are unlikely to be strong if it does occur. Otherwise, light south winds and scattered clouds expected overnight. Improved chances for thunderstorm activity expected tomorrow afternoon, and the potential is there for thunderstorms to impact the valley and any of the approach corridors. Gusty outflow winds and brief heavy rain will be the biggest concern, mainly after 20z. For the rest of southern Nevada, northwest Arizona and southeast California...Light winds favoring diurnal trends expected for most of the region. An area of thunderstorms developing out of northern Arizona is likely to impact the Colorado River Valley this evening and may bring rain and wind to KIFP and KEED between 00-06z this evening. Gusts over 35 knots will be possible. Elsewhere, SCT-BKN clouds expected overnight (especially south of I-40). Widespread thunderstorm activity returns tomorrow, with the greatest chances along and east of I-15. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && Morgan/Outler 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), 144 km away, was scanning. The volume nearest the first event began at 01:07 UTC.
5 thunderstorm wind, 5 flash flood, 1 lightning. Local standard time, as filed.
A spotter measured a gust to 58 mph, and the public reported an estimated gust to 60 mph. A large tree blew down at Wallingford and Saratoga.
The Bullhead City airport measured a gust to 58 mph, and the public reported an estimated gust to 60 mph with dense blowing dust. Winds and debris blew out a window in a home near Mohave Valley.
A spotter reported estimated gusts to 60 mph with one quarter mile visibility in blowing dust. Small limbs and street signs also blew down.
Water and mud flowed over Route 66 at Antares Road.
Visibility was down to less than a quarter mile in blowing dust.
A spotter reported 1.9 inches of rain in 30 minutes, with water running all over.
Several roads were closed due to flooding.
Lightning started eight palm tree fires and one small house fire in the Lake Havasu City area.
Boundary Cone Road was closed due to flooding.
Oatman-Topock Highway was closed due to flooding.
Thunderstorm winds capsized two boats near Body Beach.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2017Every state in 2017This day in weather historyWarnings in Arizona, August 2017
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: 714842, 714844, 714847, 714848, 714850, 714851, 714852, 714857, 714854, 714858, 714861.