Cool temperatures, with a slight warming trend over the weekend and into next week. Gusty north to east winds and drying conditions are also anticipated Saturday into Sunday with elevated fire weather conditions. Dry and quieter weather is then expected early next week. Fire Weather Watch from late tonight through Sunday afternoon. Wind Advisory from 8 AM Saturday to 2 PM Sunday.
Discussion
Trough over the Western States will deepen, as energy and cold air drops south into the great Basin region through Saturday. This will tighten the north/south gradients over Northern California producing a period of breezy to strong winds.
The Extreme forecast Index is highlighting an area of anomalously strong northerly winds down the Sacramento Valley and east to northeast winds over the Sierra and through gaps and Canyons Saturday through Sunday gusts to 45 mph are possible over the Valley and up to 55 mph over the Sierra.
Latest NBM probabilities indicate a 30-50% chance for portions of the Sierra to see wind gusts to 50 mph, with a 10-40% chance to see gusts to 40 mph along portions of the western Sacramento Valley with probabilities for gusts to 40 mph in the 50-70% range for the Delta.
A wind advisory has been issued for much of NorCal. Gusty winds could blow around unsecured objects. Tree limbs could be blown down and a few power outages may result will be main impacts.
The winds and associated drying of the atmosphere will also lead to increased fire weather conditions over some areas, although this will be mitigated for areas that received abundant rainfall last weekend and earlier this week. A fire weather watch has been issued Saturday through Sunday given the strength of the winds and the unknown amount of drying that fuels will have.
Trough will move eastward into the Central States Monday, as a short wave ridge builds over NorCal with lighter winds, dry weather and slightly warmer temperatures.
Extended Discussion (Tuesday through Friday)
Cluster analysis and ensemble guidance are in good agreement on the placement of ridging off the coast by early next week. This is expected to result in Valley winds taking on a northerly component along with gradually warming temperatures. However, high temperatures will remain below-normal.
Forecast uncertainty begins to increase by the middle of next week with respect to the timing of the ridge flattening or weakening over the Pacific Northwest.
Precipitation chances return by late next week with the NBM projecting a 20-30% probability of precipitation over the mountains/foothills and portions of the Sacramento Valley north of I-80 by Thursday evening through Friday morning.