(CBS13/NWS) Cool and unsettled weather through mid-week with periods of showers and thunderstorms, and mountain and upper foothill snow. Dry and milder weather expected to return by the end of the week.
Satellite imagery shows clouds increasing across the region as the initial frontal system works its way thru NorCal. Radar is picking up some very light returns over the northern mountains, likely some virga or very light precipitation. With the increase in clouds and wind, current temperatures are considerably milder (5-10 degrees in most areas) compared to 24 hours ago.
Shower chances will increase across the region by this afternoon as the next vort swinging around the base of the closed low off the PacNW coast moves in. At this point, it appears the best chance for showers will be generally to the north of I-80 with a slight chance of thunderstorm across the north half of the Sacramento
More significant precipitation possible for the Central Valley and northern Sierra Tuesday and Wednesday as the closed low drops south to near the Bay Area. The pattern is a classic late winter/early spring heavy snow producer for the northern Sierra with a prolonged period of southwest flow along with steep mid-level lapse rates generating significant snow despite rather meager overall moisture (TPW around 1/2 inch). Thunderstorms will also be possible each day with small hail expected to be the primary threat, though shear parameters indicate the potential for some longer-lived storms should sufficient instability materialize.
A winter storm watch has been posted for the far southern Cascade Range and northern Sierra for Tuesday afternoon into Wednesday evening. Several feet of snow will be possible with accumulating snow possible down into the upper foothill elevations leading to significant travel impacts.
A drier weather forecast will return Thursday as the low digs south
into SoCal and western Arizona.
EXTENDED DISCUSSION (Friday through Monday)
Upper ridging builds inland over interior NorCal Friday into
Saturday. Dry weather expected during this period with above normal high temperatures. The Ridge axis moves through early Sunday as the Pacific frontal system approaches the CWA. More progressive GFS
introduces some precip north of a KUKI-KRBL-KAAT line Sunday afternoon. Short wave trough moves through Sunday night with a
threat of showers, mainly over the mountains and northern
Sacramento Valley. The drier northwesterly flow aloft sets up over the forecast area Monday.
MONDAY: 20% chance of rain with a high of 60 and a low of 44
TUESDAY: Chance of thunderstorms with a high of 57 and a low of 43
WEDNESDAY: Chance of thunderstorms with a high of 56 and a low of 37
THURSDAY: Mostly sunny with a high of 62, and a low of 37
FRIDAY: Mostly sunny with a late chance of showers, a high of 66, and a low of 36
SATURDAY: Cloudy with an early chance of showers, a high of 67, and a low of 41
SUNDAY: Mostly sunny with a high of 65 and a low of 41
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