textproduct: Reno

KEY MESSAGES

* Mild spring weather continues through Thursday, then a spring storm will bring notably cooler weather, widespread rain, and mountain snow this weekend.

* Isolated thunderstorms are possible for the E.Sierra and far W.Nevada Thursday afternoon, with more scattered thunderstorms and widespread precipitation expected on Friday.

* Sierra snowfall impacts are expected by Saturday morning as snow levels drop below 7,000 feet. Winter Storm Watches have been issued.

DISCUSSION

A roller coaster springtime pattern will be in store this week as conditions transition from seasonably mild and dry to cooler and wetter with Sierra snow impacts expected, driven by a spring low pressure system tracking inland this weekend.

Highs remain around 10 degrees above average through Thursday, generally in the low 70s across western Nevada and low 60s for Sierra valleys. As moisture and instability increase in the region, we will begin to see 20-40% chances for showers this afternoon across portions of Plumas and Lassen Counties which may extend into the Surprise Valley and far northern Washoe County. Isolated thunderstorms (10-20% chances) are possible over portions of N.Lassen into far NW Nevada today.

Shower chances increase on Thursday (25-50% for the Sierra, 10-20% for far W.NV), along with a 15-25% chance of thunderstorms. Friday will see the most potential with >60% chance of showers areawide and around a 15-30% chance of isolated to scattered thunderstorms across the E.Sierra into the Sierra Front. Snow showers may be limited to high elevations of the Sierra on Friday with snow levels generally hanging around 7500-8000 feet.

On Saturday, the latest snow level trends have lowered nearly 1000 feet over in the last 12-24 hours with snow levels dropping below 7000 feet by Saturday morning. At this time, rain could begin to transition to snow by Friday night with travel impacts across the Sierra expected for Saturday and Sunday. At this time, chances of seeing over 2 feet of snow are over 55% along Sierra crest passes with around 6-12 for Mono County counties west of US-395 (above 8000 feet) and 6-10 around lake level in the Tahoe Basin. Winter Storm Watches have been issued for these areas.

Expect gusty south- southwest to accompany this storm with gusts 30-40 mph expected for most areas with over 50 mph for wind prone areas. Most snow impacts should begin to wane by early Monday morning with drier and cooler conditions prevailing. Fuentes

AVIATION

* VFR condition will prevail this afternoon with westerly afternoon winds gusting up to around 20 kts. Generally less than a 10% chance for isolated showers for KTRK and KTVL with 20-40% chances north of KSVE this afternoon.

* The precipitation chances will then increase and become more widespread along the Sierra crest and into the Sierra Front through the remainder of the week.

* Snow impacts for Sierra terminals are looking more likely by Saturday with generally around 5-10 inches of accumulation possible for KTRK, KTVL, KMMH.

AVALANCHE

Increasing chances for periods of moderate to heavy snowfall in the Sierra this weekend:

* Friday: 70-90% chance of showers with 15-30% chance of thunderstorms in the afternoon along the eastern Sierra. Any snow impacts will be limited to higher elevations above 8000 feet through Friday afternoon with 1-4 inches of snowfall possible along the Sierra crest. Snow levels will fall below 7000 feet by Friday night.

* Saturday-Monday Morning: Snow levels have trended much lower recently with snow levels lowering below 6500 feet by mid- morning Saturday. Snow ratio around 8-10:1 are expected on Saturday before increasing near 12:1 by Sunday. While timing remains low confidence at this time, the heaviest rain and snow rates are targeting Saturday afternoon-evening. SWE of 2.5-2.75" is possible along the Sierra crest by Monday morning along the Tahoe Basin with near 2.0" in Mono County. Snow totals nearing 3 feet along the Sierra crest in the Tahoe Basin are possible with around 2 feet for the crest in Mono County. Strong and gusty south-southwests winds are expected on Saturday with ridgetop gusts of 80-100 mph expected. Fuentes

REV Watches/Warnings/Advisories

NV...Winter Storm Watch from Saturday morning through Sunday evening NVZ002.

CA...Winter Storm Watch from Saturday morning through Sunday evening CAZ071-072.

Winter Storm Watch from Friday evening through Sunday evening CAZ073.