A cutoff low near the southern California coast helped fuel isolated thunderstorms over southern San Bernardino County. One storm produced severe weather.
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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 near the southern California coast helped fuel isolated thunderstorms over southern San Bernardino County. One storm produced 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 Sep 24, 12:10 PM PST, 1 hour 5 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 110 PM PDT Fri Sep 24 2021 .SYNOPSIS...Isolated showers and thunderstorms can be expected mainly southeast of I-15 this evening and again on Saturday, followed by a better chance in Mohave County on Sunday. Near or slightly above normal temperatures will continue through early next week before breezy winds and a brief period of cooler conditions arrive for the middle of next week. && .SHORT TERM...through Sunday night. Early afternoon satellite loop showed cumulus bubbling over the Spring Mountains as well as the higher terrain southeast of I-15. Deeper cumulus were along and south of a line from Kingman to Twentynine Palms, with a few thunderstorms along I-10 in Riverside County, fueled in part by a cutoff upper level low pressure just south of Tijuana. Chances for thunderstorms will slowly increase from the Morongo Basin to the Mojave Preserve to the Hualapai Mountains as the atmosphere destabilizes this afternoon, then quickly end after sunset. The upper low is forecast to drift west tonight and Saturday, leading to another afternoon of only slight chances for storms in our southern CWA, with plenty of sun for areas along and northwest of I-15. By Saturday night, low pressure which was near 38N 153W this afternoon will be reaching the Pacific Northwest, close enough to kick the cutoff low northeastward. This will bring increasing chances for showers and thunderstorms to areas southeast of I-15 Saturday night through Sunday, with the best chances in Mohave County Sunday. Newer model runs have backed away from earlier forecasts of up to a half inch of rain in Mohave County, with new data suggesting amounts over a quarter inch will likely be confined to the far eastern and southeastern portions of the county. This implies a lower risk of flash flooding on the Flag Fire scar than previously thought. By Sunday night, precip chances should be coming to an end, with wraparound clouds on the back side of the low also clearing out as the night goes on. .LONG TERM...Monday through Thursday. Closed low responsible for scattered convection in southern parts of the forecast area over the weekend will drift into the southern Rockies by early next week. Meanwhile, a short wave ridge will very briefly build into the region Monday before a much stronger trough pushes into the West Coast on Tuesday. Gusty winds will materialize ahead of the trough as pressure gradients tighten, especially across the Western Mojave Desert and I-15 corridor. This will be followed by a frontal passage on Wednesday with temperatures cooling a few degrees below daily normals. Thereafter, confidence in forecast details degrades as ensembles hint at holding back some energy over the Great Basin, and possibly closing off a weak low somewhere between the Great Basin and the Four Corners. The main influence of this feature, should it materialize, would be to reduce the temperature rebound behind Wednesdays front. The latest NBM deterministic forecast favors the cooler side of the temperature envelope along with about 2/3rds of the cluster guidance members, suggesting near normal temperatures to finish off the week. && .AVIATION...For McCarran...Expect light winds following typical wind patterns with easterly winds in the afternoon and southwest winds in the evening. Some FEW aoa 12-15 Kft along the higher terrain will be possible this afternoon. More cloud cover is expected tomorrow. No other impacts are expected. For the rest of southern Nevada, northwest Arizona and southeast California...Winds are expected to remain mostly light following typical diurnal trends across the region through tomorrow morning. Some occasionally breezy southerly winds with gusts around 15 knots are possible tomorrow afternoon across the region. A few isolated showers and thunderstorms are possible this afternoon and again tomorrow, but are not expected to impact any TAF sites. Residual lofted smoke from yesterday is keeping a mid-level deck of hazy skies across the western Mojave Desert. These hazy conditions are expected to scattered out through the remainder of the afternoon. Closer to the wildfires, periods of light winds may bring smoke and haze into the Owens Valley Saturday morning, occasionally reducing visibilities at KBIH down to 5-6 SM. Outside of potential impacts from smoke and haze, no other significant impacts due to weather are expected. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && SHORT TERM...Morgan LONG TERM...Outler AVIATION...Peters 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), 115 km away, was scanning. The volume nearest the first event began at 21:13 UTC.
1 hail. Local standard time, as filed.
Lots of small hail fell in and around Yucca Valley, with a few stones as large as one inch in diameter.
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, September 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: 984988.