Pattern change to cooler weather starts Sunday. Chances for precipitation Monday and again mid to late week, with periods of locally breezy winds. Near to below freezing overnight lows in the Valley Tuesday-Wednesday mornings. Another weather system mid to late week next week bringing light rain, heavy mountain snow and breezy winds.
Discussion (Tonight through Monday)
Gusty winds up to 25 mph over the north and west end of the valley will taper off this evening. A cooling trend will start on Sunday as a low pressure area approaches the region. Slightly cooler air and some cloud cover will start to trend temperatures downward.
The weak trough will move through the region late Sunday night through Monday night. Precipitation amounts look very light with only up to a couple of inches of snow expected. Snow levels look to be between 3500 and 4500 ft. Precipitation in the valley will be very sparse with the best chances over the north end of the valley. Most valley areas are expected to remain dry.
Colder air behind this system will lead to a couple of cold morning temperatures. Temperatures Tuesday will should lower into the mid 30s with areas of frost expected in the morning. Daytime highs will be in the 50s for the valley.
Extended Discussion (Wednesday through Saturday)
Wednesday morning will start out very cold and will be the coldest day of next week. Temperatures are mainly forecast around freezing in the valley with some of the colder spots dipping into the upper 20s. Zonal flow will set up ahead of a system that will be dropping down from the north. Cooler air and some cloud cover is expected to keep temperatures in the 50s for the valley.
Wednesday night into Friday morning the system will move through the region. Models are mixed on the snow levels generally ranging between 4500 to 6000 feet for most of the storm with the higher elevation favored by the European model. Snow levels over the Southern Cascades will be about a thousand feet lower than what was earlier indicated.
Another system will move into the region next Saturday. The European is much wetter and stronger than the GFS at this point and ensembles seem to be doing a blend of both. GFS wants to bring a dry day for most of Friday with the European the NBM favoring continued rain. High uncertainty with this later storm continues at this time.