October 26, 2017 – Dry and warm weather continues with above normal temperatures through the weekend. A slow cooling trend through the middle of next week but remaining warmer than normal. Cooler with a chance of precipitation the end of next week.
High pressure aloft amplifies over the west coast today bringing continued warm and dry conditions with daytime highs remaining well above normal. Overall airmass today looks equally warm as Wednesday so have increased high temperatures a bit today to match better with latest guidance. Northerly winds increase a bit today as upper ridge builds in but do not become significantly strong. The upper ridge will slide across the west coast over the next couple of days continuing the dry conditions and above normal temperatures going into the weekend. Upper ridge begins to break down early next week bringing the start of a cooling trend but Sunday will still remain several degrees warmer than normal.
Extended discussion (Monday through Thursday)
High pressure over the northeastern Pacific will drop southward early next week, bringing dry weather and continued warm temperatures across the region.
Longer-range models hint at the weather pattern finally changing mid-to-late next week, as a positively-tilted trough drops south from Canada and breaks down the ridge. Both the GFS and ECMWF bring moisture into Northern CA, but the 00z GFS takes a wetter trajectory and taps into more subtropical moisture than the ECMWF.
The CPC 8-14 day precipitation outlook also hints at this pattern change. We have started to increase the forecast chance of precipitation for late next week, with the understanding that forecast details will likely change substantially the next few days.