Between today and tomorrow, afternoon highs will drop from the mid 70s to the mid 50s.  We will also have to keep a close eye on thunderstorms, rain and low snow in the Northstate tomorrow.

A very cold low pressure system, especially for early November, will drop into the Northstate late tonight.  However, the moisture tap for this system will be very low.  Most of what we see in the valley and even in the higher elevations will be scattered activity.  There will probably be a little more up-slope flow off to the east and southeast in the western slopes of the Sierra.  

Also the ground will still be fairly warm so what we might see is some melting during the day and maybe refreezing at night under very cold temperatures.  This really only has a chance in locations that see decent snow accumulations which we're not really expecting anyways.

Overnight lows for the valley floor will drop into the mid 30s Friday morning through Sunday morning, which will be the coldest temperatures we've seen since April.

Things start to slow down by late Friday, as a more stable north wind moves in.  Yet temperatures will still remain below normal through the extended forecast.