textproduct: Sacramento

KEY MESSAGES

- Moderate travel impacts Friday through Monday, from heavy mountain snow and wind. Minor travel impacts for the foothills and valley.

- Unsettled weather pattern continues into next week.

..Friday through Monday

The main synoptic level system over the Pacific moves toward the coast on Friday bringing sufficient moisture and instability toward the region. Precipitation overspreads the region Friday through the weekend and continuing into the early part of next week. Moderate to possible heavy rainfall at times, with rain rates up to a half in per hour possible. Forecasted rainfall will range between 1 to 3 inches, with the highest in the foothills. Locally higher amounts can't be ruled out if any area experiences training thunderstorm chances. These chances are low at this time. Thunderstorm chances increase Saturday and into Sunday morning as an instability axis sets up along the coast and into the Valley. MUCAPE reaches 500 J/kg, with sufficient moisture transport, and low level shear. A stray stronger storm can't be ruled out Saturday afternoon/evening and again Sunday morning. This is where the potential exists for rainfall rates reaching a half in per hour around thunderstorms. Rain will continue into Sunday afternoon/evening and again early next week.

As the system moves onshore, colder air will push down from the north helping drop snow levels. Friday into Saturday snow levels, remain around 6500-7500 feet and drop off toward 5000-6000 feet late Saturday and into Sunday. Latest guidance wants to push out the colder air moving down from the north toward Sunday and into Monday, which would cut into some of the snow totals. Accumulations are uncertain at this time but may range from 2 to 4 feet above 5000 feet. Locally higher amounts are possible at higher elevations. Winds could gust as high as 45 mph and cause dangerous travel conditions when combined with the heavy snow. If you plan to travel this week and into the weekend, make sure you have alternate routes, backup plans, and carry a safety kit with you at all times.

Long range guidance looks to continue the feed of moisture and instability into the region mid next week bringing further precipitation, mountain snow, and breezy conditions.

AVIATION

Visibilities improved today, with a few MVFR conditions lasting through this afternoon. Ceilings have increased, with a few locations near MVFR otherwise VFR. Rain will move in from the south this afternoon and evening becoming widespread later this evening and overnight. Ceilings drop to IFR/MVFR, with visibility reductions. Rain continues overnight and throughout tomorrow, with IFR/MVFR conditions.

STO WATCHES/WARNINGS/ADVISORIES

Winter Storm Watch from Friday afternoon through Sunday morning for West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.