textproduct: Las Vegas

KEY MESSAGES

* Unsettled conditions expected in our far northwestern areas through Monday, though any impacts should be minor.

* Dry and mild conditions prevail across the rest of the area with breezy afternoons over the southern Mojave Desert.

* The chance of rain, snow, and wind impacts around Christmastime continues to increase.

DISCUSSION

through Christmas Day.

A shortwave trough passing through the PacNW today will kick up strong winds in the Sierra, with a 75% chance of 60+ mph gusts. As a result, a Wind Advisory has been issued for our Sierra zone from 7AM this morning through 4AM Saturday. Down in the Owens Valley, breezes should be more in the 20-35 mph range, but a few gusts of 40-45 mph cannot be ruled out (25%). The aforementioned shortwave will also direct a plume of moisture into the central Sierra Saturday - Monday. The mountain range will intercept the majority of precipitation, with up to 1.50" of liquid equivalent at the crest. However, snow levels are forecast to be 9-10 kft throughout the event, so the potential for winter impacts is limited. In the northern Owens Valley, there is a 25% chance of seeing more than 0.10" of rain during this time period.

Elsewhere, dry conditions prevail as precipitation chances stay below 10% through Monday. High temperatures will continue to run 10- 15 degrees above normal. Breezy afternoons are expected across the southern Mojave Desert, with gusts 15-25 mph likely (70%) along the I-15 and I-40 corridors south of Las Vegas.

Models continue to hone in on an impactful system around Christmastime. Latest guidance has precipitation chances moving in as early as Tuesday and sticking around through Christmas day. Forecast PWAT and IVT values are near the max of December climatology, so moisture will not be a limiting factor. The record December PWAT value in Vegas is 1.00" set in early December 2014. Looking back at that date, Vegas only got 0.16" which is a nice rain but nothing crazy (not even in the top 50 wettest December days). This is a nice reminder that moisture is only part of the rainfall equation. Forcing (lifting mechanism) is crucial as well and the strength, track, and timing of the forcing with the upcoming system remains uncertain. Mountains benefit from the ever-present forcing that is orographic lift, and will almost certainly fair well with this system due to the strong moisture flux. The biggest question for our mountain locations is snow level. With deep moisture often comes a deep layer of warm air. Looking back at the early December 2014 event, Mt. Charleston (town) received nearly 2.00" of rain and ZERO snow. This could very well be the same scenario here, as forecast snow levels range from 6.5-7.5kft in our northwestern areas to 9-10kft in our southeastern locations. We're still over 5 days out from the bulk of the precipitation so things can, and will, change. But the key takeaways should be that weather impacts are growing more likely around the holiday. Those with travel plans should be prepared for wet conditions on most roads and wintry weather above 7-8kft.

AVIATION...For Harry Reid...For the 12Z Forecast Package

Winds will generally remain light and variable through mid-morning before turning northeast to east from late morning through the afternoon. There is a low chance (less than 20 percent) for elevated south or southwest winds Friday evening after 23Z, but most likely conditions will continue to feature typical southwest winds under 8 knots. VFR conditions will prevail, with periods of high clouds with bases AOA 20kft AGL.

For the rest of southern Nevada, northwest Arizona and southeast California...For the 12Z Forecast Package...Winds across much of the region will follow typical wind patterns, with speeds generally 10 knots or less through this evening. The exception will be at KBIH, where light northwest winds are expected in the morning before becoming gusty at times out of the north to around 20 knots after 19Z. Winds are then expected to settle back to around 10 knots during the evening. VFR conditions will prevail through tonight, as bands of high clouds stream over the region, with bases remaining AOA 15kft AGL.

CLIMATE

Numerous climate locations have a forecast high temperature and/or forecast warm low temperature within 3 degrees of the daily record for Wednesday, Thursday, and Friday.

The table below shows the daily record maximum temperature and the year the record was last set. An asterisk (*) denotes which records are in jeopardy (within 3 degrees of the forecast).

MAX FRI, DEC 19 SAT, DEC 20 SUN, DEC 21 Record(Yr) Record(Yr) Record(Yr)

Las Vegas 68(2024)* 73(1981) 68(2023)* Bishop 69(1985)* 71(1972) 70(2018) Needles 76(2024)* 76(1981)* 75(2005)* Daggett 76(1950)* 78(1981) 76(2018)* Kingman 76(1917) 74(1917) 73(1917) Desert Rock 69(2024) 69(2020) 70(2020) Death Valley 75(1950) 79(1999) 81(1999) The table below shows the daily record warm minimum temperature and the year the record was last set. An asterisk (*) denotes which records are in jeopardy (within 3 degrees of the forecast).

WARM MIN FRI, DEC 19 SAT, DEC 20 SUN, DEC 21 Record(Yr) Record(Yr) Record(Yr)

Las Vegas 55(2010) 50(2010)* 53(2023)* Bishop 48(1999) 42(1981) 40(2023) Needles 58(2010) 61(1901) 58(2010) Daggett 48(1980)* 52(1981)* 53(1981)* Kingman 49(2010)* 51(2010) 51(1904) Desert Rock 50(2010) 45(2010)* 44(2010)* Death Valley 56(1914) 65(1999) 60(1914)

SPOTTER INFORMATION STATEMENT

Spotters are encouraged to report any significant weather or impacts according to standard operating procedures.