A big push of monsoon moisture fueled an outbreak of thunderstorms over the Desert Southwest. Many storms in the Mojave Desert produced flash flooding and severe weather.
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 fueled an outbreak of thunderstorms over the Desert Southwest. Many storms in the Mojave Desert produced flash flooding and severe weather.
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 25, 3:20 AM MST, 4 hours 10 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 320 AM PDT Tue Jul 25 2017 .SYNOPSIS...Another day of fairly widespread showers and thunderstorms is expected today. Any storms will be capable of producing flash flooding and strong winds. Gradually drying conditions are expected Wednesday through Friday with temperatures warming back to above normal. Another uptick in moisture is expected this weekend into early next week. && .SHORT TERM...Today through Wednesday Night. Showers and thunderstorms have persisted through the night, mainly over northern Clark, northern Mohave, and southern Lincoln counties. This activity has been courtesy of upper level divergence associated with a jet streak extending from the Bay Area across the Great Basin as well as a PV anomaly moving north through Mohave County. Both of these features should combine to push the centroid of activity from northeast Clark County eastward across northern Mohave County through the morning. Just as that convection moves out of the area, more general daytime convection is expected to fire late this morning/early afternoon. Only weakly aided by upper level divergence associated with the aforementioned jet, this activity will be primarily orographically/diurnally driven. Therefore storms will taper off more rapidly during the evening hours (except perhaps over the far northern reaches of the forecast area where stronger divergence will exist). Current RAP/HRRR analyses indicate an axis of significant instability extending from near Lake Havasu City north to Lake Mead, then curving west toward Tonopah. This is a bit further south than previously expected and both models indicate convection firing across the southern reaches of that axis by late morning. PW values are still in the 1.5-2.0" range in those areas, and the 1.0" line extends north to Tonopah. This means that any storms that do form will be capable of Flash Flooding. As a result I opted to expand the Flash Flood Watch back south to include southern Mohave County and the Colorado River Valley. Areas that are experiencing storms early this morning (see first paragraph) will see lower (but non-zero) odds of significant thunderstorm activity later this afternoon. A secondary weak axis of instability will develop near Twentynine Palms, but overall coverage should be more isolated. Drying conditions are expected Wednesday, with storms being diurnally driven once again. The best chances will extend from the Spring/Sheep ranges north across the southern Great Basin. Chances will also exist over the high terrain of Mohave and Inyo counties. && .LONG TERM...Thursday through Monday Much quieter weather is expected for the end of the week into the weekend as high pressure works is way back over the area. A significant upper level ridge sets up over us, with increasing model agreement with the high being centered further west and that it will dry out for a few days. Decreased precip chances for Thursday afternoon from previous forecast. Heights will be increasing and with limited moisture, think precipitation activity will be isolated. Generally dry weather will continue on Friday before chances for precipitation return to the forecast. Models are not in an kind of agreement on the next push of moisture and how that will translate to shower and thunderstorm development. Some of the models bring in higher PWATs and theta-e values by Saturday afternoon, while others hold off until Sunday night. Favored the slower/drier solutions since models tend to bring in moisture too quickly. This would introduce showers and storm chances to Mohave County Saturday evening...and brings chance precipitation to the entire area by Sunday afternoon. Didnt make much in the way of chances after 18Z Sunday as confidence is too low, with general chance for precip across the entire area each day. Without a key feature to focus on for lift, it will be hard to determine where things will get active. The other thing to watch will be temperatures. Set up Friday and Saturday (and maybe Sunday depending on how quickly moisture returns to the region) is favorable for warmer than normal temperatures. 850- 700mb temperatures jump into the 30s on many of the longer term models- up from the middle 20s off this evening's sounding. A lot will depend on how quickly moisture and precip returns, which will make or break temps. Current model guidance isn't too impressive with high temperatures this weekend, and it will not be anything similar to the heatwave we saw in June, but anyone with outdoor plans Friday through Sunday should be prepared for the heat as above normal temperatures look likely. Temperatures will cool off with the wave of moisture pushing into the region. && .FIRE WEATHER...Scattered showers and thunderstorms will occur over much of the region again today with any storm capable of producing very heavy rainfall. Conditions will gradually dry out later this week, with thunderstorms decreasing in coverage each day. Temperatures will be near normal to somewhat below normal through Wednesday, before returning to slightly above normal late in the week. Another uptick in monsoon moisture is expected to arrive sometime this weekend. && .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. 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...Low confidence forecast for today as shower and thunderstorm activity continues. Currently have showers developing just to the north of the Valley, extending south into eastern parts of Las Vegas. Expect this first round of precipitation to continue the next few hours before it gets shoved eastward away from the LAS area. In addition to the precipitation, an outflow boundary developed and shifted southward through the airspace, veering winds to N-NE with gusts to around 15kts. This should also last about 2 or 3 hours at VGT and LAS before winds go variable again. After a brief lull this morning, more scattered shower and thunderstorms may develop this afternoon. Hard to say if things will get going in the Valley as the current precip may decrease redevelopment later today, however confident enough to keep it in the TAF forecast. If the Valley were to see more showers and storms, the most likely time period would be between 20Z-00Z. After 00Z, will need to watch if storms continue or quickly die off as models show both solutions. Anything that does develop has the potential to produce heavy rain, with lower ceilings below 100kft as well. Low confidence in the wind forecast for this afternoon too, as wind direction will depend on precipitation redevelopment. Current TAF forecast would be without the influence of storms. Quieter and drier conditions should return by late Wednesday morning. For the rest of southern Nevada, northwest Arizona and southeast California...Scattered showers and thunderstorms are again possible this afternoon, with the better chances over northwest AZ and southern NV. Will need to watch development and wind directions, especially in southern CA into the Colorado River Valley. .SPOTTER INFORMATION STATEMENT...Thunderstorms capable of strong winds and flash flooding are possible once again today. Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && SHORT TERM/FIRE WEATHER...Wolcott LONG TERM/AVIATION........Allen 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), 34 km away, was scanning. The volume nearest the first event began at 14:31 UTC.
7 flash flood. Local standard time, as filed.
Willow Beach Road was closed due to extensive flood damage, and Temple Bar Road was also closed due to flooding.
A tour bus was stuck when Pierce Ferry Road was flooded by a wash.
Flash flooding blocked Gregg's Hideout Road, trapping cars.
Stockton Hill Road was closed from Cactus Wren Road to Pierce Ferry Road due to flooding.
Signal Road was closed due to flooding.
Hackberry Road was closed due to flooding.
Blake Ranch Road was closed due to flooding.
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, July 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: 709558, 709559, 709560, 709561, 709562, 709563, 709564.