Cooler with rain, mountain snow and wind, then warmer

October 18, 2017 – Dry and mild weather today. Rain chances along with high mountain snow and cooler temperatures Thursday and Friday followed by a warming trend this weekend into early next week.

Discussion

High cloudiness has shifted further south overnight as west- southwest flow increases ahead of the approaching late-week trough. Winds remain generally light and temperatures are running a bit cooler compared to 24 hours ago across most of the area.

Dry weather with mild temperatures will continue across the region today. Highs this afternoon are expected to be very similar to Tuesday’s with lots of lower to mid 80s throughout the Central Valley and surrounding foothills.

Unsettled weather still ontrack to return to the region Thursday and Friday with precipitation, much cooler temperatures and gusty southerly winds. The wetter mountain areas may see as much as an inch of liquid precip while the valley will generally see less than a quarter inch and most locales probably just a few hundredths. Colder air behind the frontal band is expected to lower snow levels below the major passes on I-80/US-50 where an inch or two of snow could accumulate.

Gusty ridge winds can be expected later Thursday as the upper trof moves inland with a southerly 6-7 mbs RDD-SAC gradient forecast (not as strong as yesterday) leading to gusts around 30 mph or so. Also, chance of a stratus intrusion into the Sac Vly Thu morning ahead of the deepening trof, unless the trof mixes it out beforehand.

Warm frontal clouds could return Fri night with WAA precip mainly staying to our N as strong ridging begins to build for the weekend.

Extended discussion (Sunday through Wednesday)

Upper ridging over NorCal on Sunday will bring dry and warm weather to the region into midweek. Valley & Delta highs on Sunday will be in the upper 70s to low 80s warming into the mid to upper 80s for Monday and Tuesday.

Foothill and Mountain regions will be 60s to 70s on Sunday with foothills warming into the low 80s for the start of the work week. A few degrees of cooling possible on Wednesday when a weak trough could approach NorCal.