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KEY MESSAGES

* Snow showers above 8000 feet and valley rain today, with falling snow levels by mid week.

* Wednesday into Thursday will feature a colder air mass and strong downsloping winds that will create travel impacts for land, air, and water.

* The end of the week into the weekend will see a return of warmer temperatures and lighter winds.

DISCUSSION

Precipitation has been falling around the region this morning, bringing wet roads across the Sierra, mostly in the Tahoe Basin as of this writing. We expect to see this continue, with periods of showers throughout the day. Snow levels are starting around 7500 to 8000 feet, and will begin to fall toward 7000 feet by sunset this evening. During the afternoon hours, some showers may be capable of producing lightning, especially over the Basin and Range today as 15- 25% chances for lightning appear in ensemble guidance. Overnight, this lightning threat shifts to the Sierra, highest (10-15%) west of the Tahoe Basin.

As Wednesday arrives, a noticeable temperature drop arrives for overnight lows as the next weather feature drops in along the Alaskan coastline into the Pacific Northwest. The placement of this trough will allow not only colder air to filter in, but also bring strong to damaging downsloping wind gusts by Wednesday afternoon. Gusts of 100+ mph will reach Sierra ridges late Wednesday into Thursday, while ample mid-level dry air will be allowed to mix to the surface. Wind prone areas could see gusts up to 80 mph with gusts to 60 mph possible down to valley floors along the Sierra Front. Across the Basin and Range, winds will gust near 60 mph across Mineral County, while Pershing and Churchill will see gusts to 50 mph. This brings all kinds of concerns to the region, from bumpy flights in and out of area airports, to waves on Lake Tahoe up to 6 feet and up to 5 feet on Pyramid Lake. Blowing dust could be lofted over the Basin and Range as westerly winds cross dry lake beds and sinks. Recreating outdoors may prove difficult and uncomfortable with whipping gusts and cold temperatures across the entire region. Finally, there is also a risk of elevated fire weather conditions during the Wednesday into Thursday time period. We advise foregoing any activity that could create a spark, since winds are capable of carrying sparks, and we have already seen a couple small fires appear in Monday's winds. This wind activity will remain overhead through late Thursday afternoon into evening.

Snow levels will fall to around 3,500 to 4,000 feet by early Thursday morning, when the bulk of the moisture will have moved out over the Basin and Range, with only lingering showers across northeastern California. Shower activity will continue to advance eastward through Thursday, although the Sierra could continue to see lingering showers into the evening. Despite the lowering snow levels, recent warmth and high sun angle will keep roads mostly wet as opposed to allowing snow to accumulate. The only caveat would be the early Thursday morning commute, when the colder air may allow for some slushy accumulations along the side of area roadways above 7000 feet. Overall accumulations will be greatest along the Sierra crest where generally 6 to 12 inches will fall over Mono County. Expect up to 10 inches along the ridges overlooking the Tahoe Basin, with a 35% chance for Donner Pass to add up to 12 fresh inches of snow. Lake level could see accumulations of 1 to 4 inches with the higher accumulations along the western shore.

Friday morning will be the coldest of the week. So, if you've already got outdoor plants popping out of the soil, you may want to consider protecting them by Wednesday night through Friday morning to keep them from wilting. As for showers, we could see some lingering showers over the Basin and Range, but the majority of the region will be on a warming and drying trend by Friday that will bring us into the weekend. Our longer range outlooks suggest that warming trend will be met with a drying pattern, although some guidance suggests we could be looking at another mid week system for next week, although confidence is low at this time. HRICH

AVIATION

* SHRA will continue across KTVL and KTRK this afternoon, with periods of spillover into KRNO/KCXP/KMEV. Intermittent periods of showers will also appear over KMMH today. Amounts will be light for KRNO/KMEV/KCXP/KMMH while KTVL/KTRK could accumulate 0.5"- 1.00" of liquid water. LLWS and turbulence has been present over the Sierra terminals today, which will relax into the afternoon, and then intermittent periods of LLWS through 18z Wednesday.

* Increasing westerly winds will become strong gusts Wednesday into Thursday, bringing more LLWS and turbulence with FL100 winds around 75-80 kts, mixing gusts of up to 40 kts to leeside valley terminals KRNO/KMEV/KCXP by Wednesday 21z and lasting through 15z Thursday. HRICH

FIRE WEATHER

Strong to locally damaging downsloping winds are anticipated for Wednesday evening into Thursday morning. A High Wind Watch is in effect for the Sierra and Sierra Front from Wednesday afternoon through Thursday morning. Westerly winds will bring 70 to 80 mph gusts to wind prone locations, such as Washoe Valley and favored canyons across Mono County. With the concentration of strongest gusts arriving overnight, this will lead to poor overnight recoveries Wednesday night. Recent warmth and eroding snowpack exposing areas of vegetation may have allowed some fuels to become receptive to sparks, and high winds could carry sparks into those receptive fuels. HRICH

REV Watches/Warnings/Advisories

NV...Wind Advisory from 2 PM Wednesday to 11 AM PDT Thursday NVZ001- 004-005.

High Wind Warning from 2 PM Wednesday to 11 AM PDT Thursday NVZ003.

Winter Weather Advisory from 5 AM Wednesday to 8 AM PDT Thursday NVZ002.

CA...Wind Advisory from 2 PM Wednesday to 11 AM PDT Thursday CAZ070.

High Wind Warning from 2 PM Wednesday to 11 AM PDT Thursday CAZ071-073.

Winter Weather Advisory from 5 AM Wednesday to 8 AM PDT Thursday CAZ072.

Winter Weather Advisory until 5 AM PDT Wednesday CAZ073.