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KEY MESSAGES

* Colder this weekend with rain and mountain snow increasing this evening and overnight, producing winter travel impacts for the Sierra. Rain and snow showers continue through Sunday evening.

* A slight 10-20% chance for additional thunderstorms continue through Sunday afternoon.

* Periods of gusty-strong winds this weekend, with peak gusts in the Sierra extending into Mineral County from late this afternoon through late tonight.

DISCUSSION

* Storm Timing through Tonight: We're currently in a break between yesterday's activity and the arrival of the main storm toward sunset, apart from a few light showers near/west of the Sierra crest with snow levels near 7000-7500 ft. The latest high resolution guidance continues to indicate increasing precip rates in the Sierra/northeast CA between 5-8 PM with little change in snow levels. Then from late evening and overnight as the main low moves onshore accompanied by a cold front, snow levels will quickly drop to lake level around Tahoe and then bottom out to near 4000-4500 ft in the pre-dawn hours Sunday, near the tail end of the main precip band.

* Winds through Sunday: Ahead of this precip band, S-SW winds will continue increasing later this afternoon through tonight. Signals point to a 4-6 hour period of stronger gusts near 50 mph with wind prone areas reaching 60 mph in Mineral/southern Lyon County, therefore a Wind Advisory was issued. Elsewhere we can expect gusts of 25-40 mph with a few gusts to 50 mph in wind prone areas and also briefly along the cold front. Sierra ridge gusts peak at 80+ mph tonight, and remain in the 50-70 mph range through Sunday evening before diminishing overnight. As for winds today, expect southerly winds across the region. We'll see another round of brisk SW-W winds on Sunday, with gusts mainly 25-35 mph.

* Sierra Snow Rates through Sunday: Guidance still shows a period of heavier snowfall rates reaching 2-3"/hour from around 10-11 PM late tonight through 3-4 AM Sunday morning in the Sierra. Avoid travel if possible across Sierra passes as roads will rapidly become snow covered. For the latest forecast snow totals with this storm, please see the current Winter Storm Warnings. Additional snow shower bands developing during the day Sunday could produce brief 1-2"/hour snow rates and produce periods of slick travel especially for Sierra passes. The shower activity is projected to wind down Sunday evening.

* Foothill/Lower Elevation Rain/Snow: The majority of precip in western NV will fall as rain (ranging from trace amounts to 0.20", except up to 0.50" for foothills). However, snow levels will drop low enough for snow in foothill locations early Sunday morning around western NV. Current guidance shows a 30-50% for up to 1" of accumulation above 5000 feet, including Virginia City. We also can not rule a brief rain/snow mix on the valley floors in western NV early Sunday morning, but given the recent warm conditions, no accumulations are anticipated.

* Thunderstorm Chances This Weekend: Thunderstorms currently over the I-5 corridor will approach the Sierra through this afternoon. However, these storms will move into limited instability with thicker cloud cover in place, keeping the chance for lightning below 20% near the Sierra crest northward to western Lassen County. Then with the cold front tonight, a few lightning strikes could pop up over northwest and west central NV, and also in the Sierra during the peak snow intensity. Sunday's chilly and showery regime with colder air aloft as the upper low center approaches western NV sets up the stage for isolated lightning with rain/snow or pellet showers, with this potential favoring northeast CA and west central NV near/east of US-95. Storm coverage and intensity will be much less compared to Friday afternoon. * Sunday Night through Next Week: Temperatures dip to near freezing for western NV valleys Sunday night as cloud cover decreases. Then on Monday a cool northwest-north flow around the departing storm (along with a weak secondary wave dropping into northeast CA) could kick up a few light showers through the afternoon. We'll then see a brief warmup through midweek with highs near mid- April averages (60s for lower elevations/low-mid 50s near the Sierra) before another fast moving storm drops in with increasing winds, valley rain/mountain snow showers, followed by cooler than average temperatures through late next week. MJD

AVIATION

* FL100 S-SW wind gusts increase to 70+ kt tonight then drop slightly to 50-60 kt through Sunday, resulting in widespread turbulence and periods of LLWS especially through tonight. Surface wind gusts at main terminals near 30 kt this afternoon through Sunday afternoon, with a 20-40% chance of brief gusts near 40 kt late tonight with the cold front passage.

* Snow rates increase in the Sierra tonight, producing IFR/LIFR conditions, with 3-6" of new snow by Sunday morning at all Sierra terminals (50th percentile). Spotty additional accumulations of 1-4" Sunday afternoon-evening within snow shower bands.

* Western NV terminals will primarily be rain, but could see some snow mix with rain late tonight into early Sunday morning, producing MVFR/brief IFR conditions. Chances for any runway snow accumulation are less than 10% at KRNO/KCXP/KMEV. Isolated rain/snow/pellet showers return Sunday afternoon-early evening with brief MVFR periods. MJD

AVALANCHE

Periods of moderate to heavy snow will impact all avalanche center terrain through Sunday evening.

* Snow totals, levels, and rates: Up to 2 ft of snow along the highest peaks for SAC terrain, and up to 18" for BAC/ESAC terrain. Snow levels 7000-7500 ft this afternoon and evening, then dropping below 5500 ft after midnight with all snow across avalanche center terrain through Sunday. Snowfall rates peak late tonight with a 2-4 hour period of 2-3"/hour rates from 10 PM-2 AM for SAC terrain and 12-5 AM Sunday for BAC/ESAC terrain. Otherwise, rates of 1"/hr or less, except for brief bursts of 1-2"/hour in heavier snow shower bands between 12-8 PM Sunday.

* SLRs and SWE: Snowfall ratios initially a denser 7-10:1 for SAC terrain and 9-12:1 for BAC/ESAC terrain through this evening. SLRs increase to 11-13:1 (less dense snow) as the colder air moves in after midnight through Sunday, with up to 15:1 in Sunday afternoon's heavier snow shower bands. Additional SWE (50th percentile) through the remainder of the event mainly 1.0-1.5", with locally up to 2" for higher SAC terrain.

* Thunder potential and wind gusts: Isolated thunder (10-20%) may accompany tonight's heavy snow band along the main cold front, and also Sunday afternoon-evening. Peak ridge top wind gusts S-SW around 80 mph tonight (20-30% chance of 100 mph) and 60-70 mph Sunday.

REV Watches/Warnings/Advisories

NV...Winter Storm Warning from 2 PM this afternoon to 11 PM PDT Sunday NVZ002.

Wind Advisory from 2 PM this afternoon to 2 AM PDT Sunday NVZ001.

CA...Winter Weather Advisory from 2 PM this afternoon to 11 PM PDT Sunday CAZ071.

Winter Storm Warning from 2 PM this afternoon to 11 PM PDT Sunday CAZ072-073.