October 10, 2020 – Light showers possible in northern area today, otherwise dry and cool. High pressure returns on Sunday, bringing a stretch of warmer and drier weather to the region. Above normal temperatures return to the forecast by Monday.
An upper level trough is approaching the PacNW this morning pushing a cold front into the far northwest part of CA. The upper level trough will continue to push east today pushing a cold front into and through our area. We are seeing light showers along this cold front and that trend will continue as it pushes into our area mid morning continuing into the afternoon.
The shower chances will remain north of I-80 with the best chances over the southern Cascade. QPF will remain very light with this system with only a few hundreds possible in the northern Sacramento Valley and up to .15″ in the southern Cascade.
Clouds with this system have started to push into the Coastal Range and clouds will continue to overspread the area this morning and we can expect mainly overcast skies into the afternoon across the region. The majority of the showers will diminish during the late afternoon and evening but a few may linger over the southern Cascade into the early overnight.
The trough will be pushing into the northern Plains on Sunday as upper level ridging begins to build into NorCal. This will bring northerly flow Sunday with afternoon gusts 15-25 mph across the Valley. Northerly flow will continue into early next week but will not be as strong as Sunday.
Cool temperature are expected for today as they will be running 5-15 below average. The cool down will be short lived though as we start to warm on Sunday with highs returning to near average. Warming trend continues into next week with above average temps returning.
Extended Discussion (Wednesday through Saturday)
Above average temperatures will prevail in the extended as an upper level ridge develops over the eastern Pacific. Multiple shortwaves will ripple through the upper level flow pattern, and will periodically promote dry northerly/easterly winds.
With the continued dry fuels, this will lead to elevated fire weather conditions. October is generally the climatological peak of offshore wind events for NorCal, and unfortunately it seems unlikely that we’ll see any precipitation later next week.