559 FXUS65 KREV 262124 AFDREV Area Forecast Discussion National Weather Service Reno NV 124 PM PST Fri Jan 26 2024 .SYNOPSIS... Some isolated light rain showers are possible through Saturday across northeast CA and far northwest NV. An area of high pressure moves overhead late this weekend bringing dry conditions, light winds, and unseasonably mild temperatures into early next week. A cooler and wetter pattern looks promising by the start of February. && .DISCUSSION... * A brush-by upper-level shortwave along the northwestern periphery of a poleward building upper-level ridge will provide slight chances (10-20%) for isolated rain showers across northeast CA and far northwest NV this afternoon through Saturday night. * A little taste of spring weather is on tap through early next week as the upper-level ridge pushes northward across California and the Great Basin this weekend, providing light winds, dry conditions, and warming temperatures. High temperatures will reach into the upper 50s to low 60s across western NV and northeast CA and 50s in Sierra valleys through Wednesday. We also have a 30-60% chance of tying/breaking record warm low temperatures each morning through Wednesday at Reno- Tahoe International Airport. Some mid-to-high level clouds will accompany this ridge as Pacific-origin moisture slides around the periphery of this ridge. * Signals within the medium-to-long range ensemble guidance and the ECMWF EFI continue to show a cooler and wetter pattern affecting the region Wednesday afternoon through next weekend. An atmospheric river event looks probable, with most ensemble guidance indicating the phasing of the ideal synoptic and orographic lift superimposed over a training long and deep swath of subtropical Pacific-origin moisture. This pattern looks to provide enhanced lofting of air and the production of heavier precipitation in the Sierra and spillover precipitation into western NV. However, there are still some variations within the ensemble guidance in how the upper level jet pattern progresses into California late next week. So, this pattern is not set in stone just yet. With this being a warmer atmospheric river event, snow levels look to remain elevated, especially during the first half of the event. In any case, plan on periods of gusty winds, precipitation, and impacts to Sierra travel Wednesday through next weekend. Early snowfall projections show a 60-80% chance of 12" and a 30-40% chance of 18+" between Wednesday and next Saturday along the Sierra crest. Details of the forecast will continue to be ironed out over the next several days, so stay tuned. -Johnston && .AVIATION... * High pressure begins to take a hold over the western US through early next week. VFR conditions and light winds will prevail for all western NV and Sierra terminals. Some mid-to-high level clouds will drift across the region through the weekend. There is a 10-20% chance of isolated rain showers and virga over northeast CA and far northwestern NV through Saturday. * Several long range models are showing a medium-to-high probability of an atmospheric river event affecting the region Wednesday through next Saturday, bringing several rounds of high elevation snowfall to the Sierra, lower elevation rainfall, strong gusty winds, turbulence, and low-level wind shear. -Johnston && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$