Area Forecast Discussion
Issued by NWS Las Vegas, NV
Issued by NWS Las Vegas, NV
388 FXUS65 KVEF 221643 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 843 AM PST Fri Nov 22 2024 .SYNOPSIS...Generally dry and warming conditions into Saturday. Low pressure off the Pacific Northwest coast will sag south, directing moisture into the Sierra Friday night into Saturday. This will result in high elevation snow in the Sierra. Winds will also increase across the Mojave Desert Saturday afternoon/evening. Another system will move across the region Sunday through Tuesday, bringing more widespread rain and mountain snow chances. && .UPDATE...Another quiet morning across the region with just a few high clouds streaming across the northern part of the CWA. The main focus for today will be on snow in the Sierra beginning tonight as well as breezy to windy conditions tonight through Saturday and any potential downslope wind signal. The current forecast is in good shape and no updates are planned this morning. && .PREV DISCUSSION...223 AM PST Fri Nov 22 2024 .SHORT TERM...Today through Saturday Night. One more day of quiet weather is in store for most of the region before we begin to experience the influence of the broad trough churning off the Pacific Northwest Coast. The base of this system will slowly drop into our region tonight through Saturday night. This will result in the tail end of the associated atmospheric river to impact the Southern Sierra beginning later today through Saturday. Also, strong southwest winds aloft will spread across southeastern California and Southern Nevada tonight through Saturday night. These strong winds will primarily impact the higher mountains and lead to the potential for downslope winds. This prompted the issuance of a Wind Advisory for the Spring Mountains-Red Rock Canyon from 1 AM PST Saturday to 4 AM PST Sunday. Southern Nye/western Clark County were also included from 10 AM PST Saturday to 4 AM PST Sunday where downslope conditions will be favorable to produce hazardous crosswinds between Indian Springs and the intersection with State Route 160. Precipitation over the Southern Sierra will likely counteract downslope winds in the Owens Valley, so confidence is not high enough for impacts along Highway 395, but will continue to monitor incoming high resolution model runs. Downslope winds could impact the western Las Vegas Valley with gusts over 40 mph near the foothills, but the latest NBM indicates the majority of the metro area has less than a 50 percent chance of gusts over 40 mph. Temperatures across the desert zones will climb into mid 60s today and lower 70s Saturday aided by the southwest winds then highs will pull back to the mid 60s Sunday and winds will decrease to 10 to 15 mph as the leading edge of the trough moves past. Leftover moisture that is not intercepted by the Sierra will result in 20-30 percent chances of light precipitation mainly over the higher terrain of Clark/Lincoln and northern Mohave counties with snow levels 6500- 7000 feet. .LONG TERM...Monday through Thursday. The gradual cooling trend continues Monday as the low-amplitude ridge breaks down and troughing starts to dominate the pattern. Uncertainty currently lies in the timing as we look at Tuesday through Thursday. ECMWF and GFS ensemble members are showing progressive troughing in the Tuesday/Wednesday timeframe while CMC ensemble members are delaying the trough progressing until the Wednesday/Thursday timeframe. The solution will have a significant impact on temperatures and timing of precipitation. The current forecast has PoPs increasing Monday morning through Tuesday afternoon before tapering off Tuesday night. Highest PoPs are in the Southern Great Basin, diminishing to the south with dismal PoPs in the Eastern Mojave Desert and Colorado River Valley. Snow levels are forecast to be lower in the Sierra and White Mountains with this system as compared to the weekend system; but again, it all depends on if the coldest air coincides with the greatest PoPs. && .LONG TERM...Monday through Thursday. The gradual cooling trend continues Monday as the low-amplitude ridge breaks down and troughing starts to dominate the pattern. Uncertainty currently lies in the timing as we look at Tuesday through Thursday. ECMWF and GFS ensemble members are showing progressive troughing in the Tuesday/Wednesday timeframe while CMC ensemble members are delaying the trough progressing until the Wednesday/Thursday timeframe. The solution will have a significant impact on temperatures and timing of precipitation. The current forecast has PoPs increasing Monday morning through Tuesday afternoon before tapering off Tuesday night. Highest PoPs are in the Southern Great Basin, diminishing to the south with dismal PoPs in the Eastern Mojave Desert and Colorado River Valley. Snow levels are forecast to be lower in the Sierra and White Mountains with this system as compared to the weekend system; but again, it all depends on if the coldest air coincides with the greatest PoPs. && .AVIATION...For Harry Reid...Surface winds will be light and variable in the morning hours before settling in from the east at less than 10 kts this afternoon. Winds will shift to a westerly direction at less than 10 kts during the evening hours. Guidance shows an increase in southerly winds developing around or after 11Z Saturday morning between 10 to 20 knots. Cloud bases at or above 20 kft through Friday night. For the rest of southern Nevada, northwest Arizona and southeast California...Surface winds across most of the Mojave Desert and southern Great Basin will remain under 10 kts today and tonight. The exception will be within the Owens Valley where southerly winds of 10-15 knots will develop this afternoon, further strengthening tonight with gusts of 20-30 kts. Ceilings in western Inyo County will remain at or above 20 kft through this afternoon before starting to lower tonight when mountain tops will become obscured. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Wolcott SHORT TERM...Adair LONG TERM...Sarment AVIATION...Pierce For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter