The outer fringes of the remnants of Hurricane Rosa produced isolated 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.
The outer fringes of the remnants of Hurricane Rosa produced isolated 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 Sep 30, 2:39 PM PST, 6 hours 22 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 339 PM PDT Sun Sep 30 2018 .SYNOPSIS...Tropical moisture from Hurricane Rosa will spread up from the south and across much of the region through Monday and Tuesday. This will result in widespread rainfall, which will be accompanied by thunderstorms and possible flash flooding. Additional weather systems will move across the region keeping unsettled and cooler weather in place through the week. && .SHORT TERM...through Wednesday night. Showers and thunderstorms will ramp up over areas southeast of I-15 tonight and Monday then become more extensive Monday night and Tuesday as tropical moisture spreads up from the south. Rapidly developing intense thunderstorms propagating north from Yuma were accompanying a surge of moisture from the Gulf of California. This prompted an immediate beginning to the Flash Flood Watch for southern Mohave County and nearby sections of the Colorado River Valley. Rainfall rates around 4 inches per hour were observed near Yuma early this afternoon which gives an indication of the potential of these storms over the next few days in our area as deeper moisture moves in. The core of Rosa is still forecast to move up across northern Baja and up through Arizona on Tuesday, but the moisture will begin to be pulled across our region over the next 24- 36 hours. The 12Z GFS, NAM and ECMWF all indicated the potential for showers and thunderstorms pushing up across southern Nevada Monday night through Tuesday morning. Differential heating will be in play Monday and Tuesday afternoon which will help enhance convection along with broad upward forcing provided by the closed upper low off the California Coast. Even though individual storms will be moving rather quickly from southwest to northeast, there will be the potential for cells to repeatedly move over areas...especially downwind of mountains which will enhance flash flood potential where these bands of showers/storms develop. There are indications of a dry slot spreading in late Tuesday through early Wednesday as the coastal closed low moves inland, then additional moisture rounding the base may focus more over the southern Sierra and Inyo County Wednesday. Meanwhile, there will be lingering low level moisture to produce at least scattered showers and thunderstorms across the region Wednesday afternoon and Wednesday night as the system lifts over Nevada. .LONG TERM...Thursday through Sunday. As the zonal jet across the Pacific buckles later this week, a highly amplified longwave is expected to develop with a highly amplified ridge over the eastern Pacific and broad trough draped across the western states. This pattern will keep northwest flow aloft over the Great Basin and Mojave desert and direct a parade of shortwaves into the region. As one trough ejects into the Intermountain west Thursday morning another shortwave will quickly trail behind and eject to the east by Friday morning. That second shortwave will lack any significant forcing but may allow a few showers across the portions of the southern Great Basin along an ill- defined cold front Thursday into Friday; elsewhere, dry conditions and breezy north winds are likely. With the region between weather systems Friday, conditions will be fair outside of lingering north breezes. Temperatures will stay steady through the latter part of the week with valley highs in low 80s and higher elevations in the upper 50s to lower 60s. Operational and ensemble guidance is in fairly decent agreement on a very broad, deep upper low developing across the northern Great Basin on Saturday. This setup has the potential to bring a significant cool down along with showers and gusty north winds along a cold front. && .AVIATION...For McCarran...Gusts will continue to increase to upward of 25-30 kts before subsiding around 03-04Z. Drainage southwesterly winds between through sunrise Monday then shifting to the southeast and increasing to 12-18 knots and gusts up to 25 knots by the afternoon. Increasing low clouds with CIGS between 5-8 kft and chances for rain showers and isolated thunderstorms on Monday. For the rest of southern Nevada, northwest Arizona and southeast California...Southerly winds will continue into the evening with gusts peaking between 20-30 knots. Similar to Saturday evening, gusts are expected to subside after sunset. Southerly winds will increase to 15-25 knots again during the early afternoon Monday. By this evening and through Monday, increasing low clouds with CIGS between 4-8 kft along with increasing chances for showers and isolated thunderstorms are expected at all sites but KBIH. && .AVIATION...For McCarran...Gusts will continue to increase to upward of 25-30 kts before subsiding around 03-04Z. Drainage southwesterly winds through sunrise Monday then shifting to the southeast and increasing to 12-18 knots and gusts up to 25 knots by the afternoon. Increasing low clouds with CIGS between 5-8 kft and chances for rain showers and isolated thunderstorms on Monday. For the rest of southern Nevada, northwest Arizona and southeast California...Southerly wind speeds are expected to increase through morning with gusts peaking between 25-35 knots. Similar to Saturday evening, gusts are expected to subside after sunset. Southerly winds will increase to 15-25 knots at all sites Monday afternoon. Increasing low clouds with CIGS between 4-8 kft and chances for rain showers and isolated thunderstorms this evening through Monday. && .SPOTTER INFORMATION STATEMENT...Heavy rainfall is expected Monday and Tuesday, and perhaps beyond. We encourage spotters to report any significant weather or impacts in your area. && SHORT TERM...Adair LONG TERM/AVIATION...Boothe 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), 171 km away, was scanning. The volume nearest the first event began at 04:58 UTC.
1 flash flood. Local standard time, as filed.
Water and rocks flowed across Highway 95 in several places north of Vidal Junction. The highway was closed all the way to Needles.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2018Every state in 2018This day in weather historyWarnings in California, September 2018
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: 779384.