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KEY MESSAGES

* Rain, mountain snow, and widespread breezy to strong winds to continue through early Wednesday morning.

* Cold temperatures Wednesday and Thursday with freezes for most valley locations.

* Warming temperatures into the weekend with possible showers over the mountains.

DISCUSSION

Taking a look at the current system this morning, radar depicts an inbound line of showers moving across northeastern California. As the sun rises, showers will continue to build in over the Sierra, where snow levels this morning are hovering between 7500 and 8000 feet. Above this range, a rain/snow shower mix will start the event, while below 7500 feet will see rain as the dominant precipitation type. This system will arrive in waves today in terms of shower intensity, with another robust wave arriving mid morning, when snow levels will have dropped to around pass level, or 6500 feet. Because of the variance in snow levels through the morning, commuters traveling through Sierra passes may encounter changing precipitation types. Additionally, this afternoon's showers could contain embedded lightning strikes (15-20% chance). Due to the fluctuating precipitation types, snow amounts will be limited, and the high sun angle may work against road accumulations. Once we start to see the sunset tonight, snow levels will have fallen to around 5500 to 6000 feet, a much better setup for accumulations at Sierra passes.

By Wednesday morning, the heavier waves will have started their eastward trajectory, leaving behind a convective showery pattern. Since our lowest snow levels also coincide with showery, scattered cells, we cannot rule out a heavy burst of snow across the Sierra through Wednesday morning, but these transient showers will move quickly and therefore not amount to much in the way of widespread accumulations. All told, by Wednesday morning, pass levels could see 12-14 inches of new snowfall, with 4 to 6 inches possible for the western shores of Lake Tahoe. The eastern shores will see only 1 to 4 inches of fresh snow. As for leeside and foothill communities, the spillover seems limited by the largely southerly flow (unfavorable for spillover). We cannot rule out a light accumulation under one of the showers that pops late tonight into Wednesday morning.

Winds will remain southwesterly through Wednesday morning when they begin to turn westerly as the front passes. Wednesday morning the majority of valleys will see below freezing readings on the thermometer, and with the breezy winds subsiding, the morning may be a bit chilly and breezy. Cold air lingers late Wednesday, bringing another round of freezing temperatures to the valleys for Thursday morning. After we say farewell to this system, a warming and drying trend returns through Friday.

Hints of the troughing pattern featured as a regular part of the forecast return for the weekend. However, guidance diverges in solutions for timing and placement, just as with recent systems. It is best to keep an eye on it as it approaches, realizing the details may be fuzzy for a few days. HRICH

AVIATION

* Southwesterly gusts of 25-30 kts this morning with LLWS and turbulence through around 20z today. The strongest gusts will arrive between 21z today and 06z Wednesday. Winds will become westerly after 00z, with pockets of LLWS and turbulence returning overnight tonight across the Sierra.

* Rain showers for KSVE this morning may change to rain/snow mix after sunset tonight. KTRK/KTVL/KMMH will start with the rain/snow mix today, changing to snow after 00z tonight. Leeside terminals will see light rain showers that may transition to rain/snow mix tonight, but by that time, any spillover may become limited. HRICH

REV Watches/Warnings/Advisories

NV...Winter Weather Advisory from 5 AM early this morning to 5 PM PDT Wednesday NVZ002.

Wind Advisory from 11 AM this morning to 11 PM PDT this evening NVZ001-004.

CA...Winter Weather Advisory from 5 AM early this morning to 5 PM PDT Wednesday CAZ072-073.