October 6, 2016 – Dry weather with a gradual warming trend the rest of the week then a cooling trend next week. A chance of precipitation northern regions by mid week. Breezy north winds today then lighter north winds through the end of the week.
Discussion
High pressure building over the west coast will bring warmer temperatures today. Daytime highs should climb by several degrees but are still expected to come in a few degrees below normal. Northerly surface gradient of about 6 mb from MFR to SAC will bring breezy north winds today especially down the western side of the Sacramento valley. Upper ridge continues to slide across norcal on Friday bringing more warming with daytime highs jumping to a few degrees above normal for the first time in about a week. Light northerly winds continued but gradients weaken a bit so windspeeds should be on the decline. Western U.S. ridge forecast to amplify a bit more on Saturday making it the warmest day of the week. Daytime highs warm a bit more but still within about 10 degrees of normal. Sunday should see a bit of cooling as a weak upper trough develops off the coast bringing a shift to a more onshore flow. Changes will be only slight however with daytime max temperatures Sunday only slightly cooler than on Saturday.
Extended discussion (Monday through Thursday)
Cooling trend in the extended forecast from Monday through the end of the week. A weak upper trough moves into NorCal Monday and Tuesday which will initiate the cooling trend. Moisture with this system will be limited as we only expect a slight chance of showers on Tuesday over the Coastal Range and Northern Mountains in Shasta County. A second, stronger storm will quickly follow and impact NorCal starting Wednesday through the end of the week. This system will cause further cooling and has a better chance of spreading showers southward towards Interstate 80. Daytime highs will be near normal on Monday then drop to 5-15 degrees below normal by Thursday.