A cutoff low moved from the Pacific Ocean through the Desert Southwest, triggering a round of thunderstorms. One storm produced strong winds.
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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 cutoff low moved from the Pacific Ocean through the Desert Southwest, triggering a round of thunderstorms. One storm produced strong winds.
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 Oct 4, 7:37 PM PST, 6 hours 23 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 837 PM PDT Mon Oct 4 2021 .SYNOPSIS...Low pressure moving in from Southern California will spread showers and thunderstorms across areas mainly along and south of Interstate 15 late tonight and into Tuesday. Heaviest rainfall and best chances for thunderstorms will be across San Bernardino and Mohave counties. Another weather system will approach the region late in the week with renewed shower chances and increased wind speeds. Temperatures for the remainder of the week will tend to be below average. && .UPDATE...Diffluent flow northeast of upper low producing widespread showers and thunderstorms from San Diego County northwestward to Santa Barbara County. So far, rainfall amounts running less than a quarter of an inch. Upper low progged to move toward San Diego tonight with that diffluent flow shifting eastward across the Mojave Desert and lower Colorado River Valley where showers and thunderstorms should develop after midnight. All that development should stay along and south of I-15. Upper low will weaken and accelerate eastward into western Arizona late Tuesday afternoon. Steepening lapse rates under cold pool aloft will generate scattered thunderstorms primarily across northwest Arizona, potentially stretching as far northwest into the Lake Mead National Recreation Area. Latest HRRR accumulated QPF still showing up to a 0.50" across eastern Mohave County with latest runs now supporting locally higher amounts of 0.25"-0.50" for the higher terrain of Clark County. Updated the tonight period which lowered the PoPs, or delayed the onset of precipitation for Clark until late tonight or around daybreak Tuesday. && .SHORT TERM...Through Tuesday night. Closed low off the coast of southern California will drift inland late tonight while filling as it pushes into central Arizona. Ahead of this low, diffluent flow aloft will spread increasing clouds northward as far as the southern Great Basin this evening, with increasing shower activity to follow late tonight. As the upper low and associated cold pool lifts into the southern Mojave Desert tomorrow, steepening lapse rates and breaks in the cloud cover will result in conditions becoming increasingly unstable, and pockets of showers and thunderstorms will form under the cold pocket aloft, particuarly across Mohave county which will be near the cold core center. Brief heavy downpours and a few instances of small hail/graupel will be possible as the low moves through Tuesday afternoon. Through the duration of the storm system, chances for precipitation will be focused along and south of the I-15 corridor, with precipitation coverage becoming increasingly spotty with northward extent. Precipitation amounts overall will be quite light, with between a trace and a tenth of an inch of rain for most of the Mojave Desert region along and south of I-15, including Las Vegas. Higher amounts of a quarter to a half inch will be most favored in Mohave County from Kingman eastward. The low will lift east Tuesday evening, with shower activity diminishing with the loss of daytime heating and increasing subsidence behind the departing low. .LONG TERM...Wednesday through early next week. The weather pattern looks to remain active through early next week, resembling a more typical late fall or winter pattern than early October. As Tuesdays storms system lifts east, another trough will reload off the West Coast by midweek before penetrating inland late in the week. There remains uncertainty in the depth of this next trough, but additional shower chances will likely spread into at least the high terrain by Friday along with increasing southwesterly surface winds. This system will be a little colder than the previous, and could spread some high elevation snow into the Sierra as it moves through. Dry and cool conditions will follow for the weekend, but yet another, potentially even deeper trough is advertised by the forecast guidance by early next week. In summary, dust off the jackets, fall temperatures are right around the corner. && .AVIATION...For McCarran...Winds will follow diurnal patterns overnight and Tuesday morning before becoming more south or southeast Tuesday afternoon. Speeds should remain at 8KT or less through the period. There is a very low chance for sudden gusty winds from nearby outflows Tuesday morning, potentially from the south or southeast. A system will move through on Tuesday and will bring periods of rain and lower ceilings to the terminals. Isolated showers are possible after 09Z Tuesday are ceilings down to around 10kft are likely with the early morning precipitation. More widespread showers are then expected late Tuesday morning through the afternoon, with ceilings 6000-8000ft possible at times. Isolated thunderstorms are also possible Tuesday afternoon, but confidence is too low at this time to include TS in the TAFs. Moderate rain, lower CIGs to 5000ft, and small hail would be possible with any thunderstorms that moved over the terminals. Precipitation is expected to end Tuesday evening, with conditions improving overnight. For the rest of southern Nevada, northwest Arizona and southeast California...Increasing clouds with ceilings between 10kft-15kft are expected through the evening across the region. The chances for showers and lower ceilings to around 10kft will begin south of Interstate 40 around 06Z and spread northeast through Tuesday. The only TAF site that will definitely remain dry through Tuesday is BIH. A few thunderstorms are possible as well, especially Tuesday afternoon in far southern Nevada and western Arizona. Ceilings to around 8000ft and mountain obscuration will be possible with any showers, and lower ceilings down to 5000ft, small hail, and moderate rain would be possible with any thunderstorm. Conditions will improve Tuesday evening and overnight as rain ends from southwest to northeast. && .SPOTTER INFORMATION STATEMENT...Showers and thunderstorms are likely to impact areas mainly along and south of I-15 Tuesday. Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && UPDATE...Pierce DISCUSSION...Outler AVIATION...Nickerson For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter
The Santa Ana Mts radar (KSOX), 116 km away, was scanning. The volume nearest the first event began at 10:01 UTC.
1 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds blew down a tree in Yucca Valley.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, October 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: 989154.