FXUS65 KREV 062135 AFDREV Area Forecast Discussion National Weather Service Reno NV 235 PM PDT Sun Apr 6 2025 KEY MESSAGES... * A trough brushes the region on Monday, bringing chances for precipitation in the Sierra and breezy winds areawide. * Warming trend continues most of next week, with widespread 70s to mid 80s in the valleys, and 60s in the mountains. * Another brush-by system affects the region next weekend as precipitation chances increase across northeast California. && .DISCUSSION... Today started off with occasional high clouds with partial sunshine, light winds, and slightly above average temperatures region wide. This was all due to a sharply amplified upper ridge shifting east into the Great Basin region. As the upper ridge axis moves further east, the extensive layer of thinly veiled upper Cirrus will thicken in the increasing southwest upper flow that precedes an upper trough pushing into the Pacific Northwest this evening. As this system lifts northeast it will drag a brush-by upper short wave northeast across NE-CA and the Sierra to the Lake Tahoe basin through Monday morning. This weakly forced system will quickly lift northeast across NE-CA and the Sierra, and continue tracking east-northeast into western NV. Portions of NE-CA and the Sierra Crest to the Lake Basin Basin will see increased shower chances (50-70%) starting late tonight through Monday afternoon. There is even a non-zero chance (<10%) for isolated thunder Monday afternoon across the higher terrain areas across NE-CA. * Overall, rain showers will increase across NE-CA close to midnight, and spread east into the Surprise Valley and far northern Washoe County, and south to the Tahoe Basin with Mono County seeing little in the way of any measurable precipitation. * Snow levels will stay mostly 7000’ and above with only light, slushy snow accumulations of one or two inches topping the highest points around the Carson Range through Monday morning. Rainfall totals will range from a trace to 0.30 inches with little spillover into western NV. * Ridge winds will also increase to 70 mph overnight into Monday with generally enhanced west-southwest breezes mixing down across the Sierra into western NV. Winds are projected to gust 30-40 mph mostly north of highway 50. This will have impacts to boating/lake conditions, especially for Lake Tahoe and Pyramid Lake before the trough exits the region by Monday evening. * Therefore, lake wind advisories have been hoisted for Lake Tahoe and Pyramid Lake late morning through early evening Monday. Advisory details are available at www.weather.gov/rev/. What follows is a predominately zonal flow aloft across CA into the western US overnight Monday through Tuesday. By midweek, high pressure will amplify over the West Coast through the remainder of the week. The high pressure building across the region will bring continued dry conditions, light winds, and unseasonably warmer temperatures into the Sierra and western NV. Thursday Friday are on track for the warmest days of the week, with upper 70s to mid 80s across parts of western NV to include eastern Lassen County valleys. Highs in the mid 60s to low 70s will prevail for most Sierra communities with Mono County joining the Springtime temperature club. Ensemble simulations are showing an increasing chance for precipitation next weekend across NE-CA and NW-NV from another brush- by upper trough and attendant cold front tracking into the western US. Still a little ways out in the forecast window, so any specifics with regards to rainfall amounts and storm trajectory remain very uncertain. && .AVIATION... * Other than broken high-level cloudiness covering the region, VFR conditions and lightwinds will prevail today into the evening. A weak upper trough tracking east-northeast across NE-CA into WRN- NV will increase the FL100 southwest flow aloft to 45-55 kts overnight through Monday. Look for periods of LLWS and mountain wave turbulence for Sierra and WRN-NV terminals. * Showers and mountain obscurations accompanying this system will be confined over the higher terrain from NE-CA south to the Lake Tahoe basin. Occasional periods of MVFR conditions will start early Monday morning 10-12Z, and continue into the afternoon. With snow levels dropping no lower that 7000 feet, precipitation for Sierra terminals KSVE-KTRK-KTVL will be mostly light rain with a brief changeover to a mix with snow about daybreak. -Amanda && .REV Watches/Warnings/Advisories... NV...Lake Wind Advisory from 11 AM to 11 PM PDT Monday NVZ002-004. CA...Lake Wind Advisory from 11 AM to 11 PM PDT Monday CAZ072. && $$