Low pressure passing by to the south brought rain and isolated flooding to southern San Bernardino County.
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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.
Low pressure passing by to the south brought rain and isolated flooding to southern San Bernardino County.
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 Dec 21, 8:30 PM PST, 6 hours 12 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 0830 PM PST Thu Dec 21 2023 .SYNOPSIS...An incoming system is expected to bring widespread rainfall to areas south and east of Interstate-15 on Friday and Saturday. Heaviest rainfall expected south of Interstate-40, with flood concerns limited to the Highway-62 corridor and Lake Havasu City area, where a flood watch has been issued. Drier conditions return on Sunday while temperatures slowly warm next week. && .UPDATE...Current Multi-Radar Multi-Sensor (MRMS) imagery shows precipitation moving along the southern Californian coast, with some precipitation penetrating inland between San Diego and Santa Barbra. Water vapor and satellite imagery show the cut-off low responsible for said precipitation churning right along the southern California coast line. This system remains on track to impact our forecast area tomorrow through Saturday. However, this system is moving slower than previously anticipated. The latest HiRes guidance has caught on to this trend and now does not bring precipitation into the Morongo Basin and western Mojave Desert until around 12Z, whereas previous guidance had it moving in as early as 06Z. Despite this slight delay in precipitation onset time, the Flood Watched issued earlier this afternoon continues to look good. HiRes models continue to highlight areas south of Interstate 40 in San Bernardino and Mohave counties as areas where the highest QPF totals are expected. && .SHORT TERM...Today through Saturday. The well-advertised low pressure system coming in from SoCal is forecast to begin its turn east today. As it does, the plume of moisture and precipitation ahead of it will translate eastward as well. For today, any precipitation will be confined to our far western areas, namely western Inyo County. Despite the abundant mid- level and high clouds out there, high temperatures are forecast to be above normal across the area. Not much wind to speak of on the front side of this system, so other than some breezy east winds in San Bernardino County, light winds are forecast around the region. Early tomorrow morning, as the system begins to come ashore, increased moisture and precipitation will move into our southern deserts, spreading north and east throughout the day. Outside of the high terrain, the best chances for measurable precipitation will be along and south of the Interstate-15 corridor. In Las Vegas, the highest rain chances (50-70%) will be in the late morning through the early evening. Hi-res guidance depicts two distinct regimes of precipitation with this system. The first being the initial inland push from what's left of the atmospheric river ahead of the low. The second is wrap-around/deformation zone precipitation on the northwest side of the system. Precipitation in this regime should be relatively light and exit the CWA by Saturday night. In terms of amounts, precipitation totals will generally decrease as you move north. Many areas south and east of I-15 will see a nice, beneficial rain. Latest HREF has 30%+ probabilities of 0.25" with this system. Chances of seeing 1" or more are largely confined to locations south of I-40. Given extended time period over which this precip will fall (24-36 hours) and lack of heavy rainfall rates (10- 30% chances of 0.25"/hour), flood concerns are mainly limited to our more sensitive areas. This includes the Highway-62 corridor and Lake Havasu City. As a result, opted to issue a flood watch for these areas from late tonight through early Saturday morning. On the winter side of things, not expecting much, if any, impacts. Snow continues to fall on the Sierra and White Mountains through tonight, but amounts in populated/traveled areas are minimal. A similar story is set to unfold for the Spring Mountains, with the most impactful amounts expected to remain above populated/traveled areas. Minor impacts possible in upper Kyle Canyon and Lee Canyon, but shouldn't warrant any product issuance. .LONG TERM...Sunday through Wednesday. By Sunday, this system will be well east of us, with a northern shortwave diving south through Utah. This will keep the area dry and induce some breezy north winds, mainly in the Colorado River Valley. Temperatures are forecast to be closer to normal, with 50s and low 60s across most of the CWA. Ensemble guidance keeps the region under a northwesterly flow pattern through mid-week, resulting in dry conditions and light northerly breezes. Temperatures gradually warm to about 5 degrees above normal. && .AVIATION...For Harry Reid...Dry conditions are expected to continue at the terminal into Friday morning. Precipitation will begin approaching from the south late tonight into Friday morning but should not reach the field until after 17Z. FEW-SCT cloud bases will remain at 6-8kft through most of the night before CIGs of 6- 7kft develop tomorrow morning as the precipitation approaches and occasional CIGs below 5kft are possible in and near shower activity tomorrow afternoon and early evening. Approach paths from the south and southwest will be impacted earlier in the day with scattered showers and lower CIGs. The shower activity will continue into the evening before decreasing after 02Z. Winds are expected to remain less than 10kts through the TAF period. For the rest of southern Nevada, northwest Arizona and southeast California...Precipitation will spread south to north tonight and Friday, with most TAF sites seeing impacts at some point during the forecast period. The highest chances will be across southern areas, with KDAG, KEED, and KIFP seeing the best chance of showers starting tomorrow morning. Scattered showers are also possible in the Vegas Valley by tomorrow afternoon. SCT-BKN skies can be expected into this evening, with CIGs less than 8kft increasing south to north overnight. CIGs less than 4kft feet will be possible with the heavier shower activity tomorrow morning and afternoon. Winds will remain less than 10kts at most sites, except KDAG, where winds gusting to 20kts are expected through this afternoon before decreasing. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && DISCUSSION...Woods AVIATION...Planz 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), 110 km away, was scanning. The volume nearest the first event began at 10:39 UTC.
1 flash flood. Local standard time, as filed.
The intersection of Highway 62 and Yucca Park Rd was flooded, and water was flowing down the Morongo Grade.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2023Every state in 2023This day in weather historyWarnings in California, December 2023
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: 1147325.