March 10, 2017 – Dry and mild weather through early next week with rain chances limited to the northern mountains today. A chance of precipitation spreading southward mid to late next week with high snow levels.
Classic dirty ridge pattern over the west coast allowing plenty of high level moisture connecting back to the tropics to spread over Northern California. Radar is clear this morning except for a couple of very light showers over northern Shasta county. High clouds will likely keep any fog development at a minimum. Models indicating the threat of a few light showers will continue over northern Shasta county this morning and then over the southern Cascades and northern Sierra this afternoon as a weak shortwave rides over the ridge and into the Great Basin.
After that, remainder of short term forecast is completely dry as the west coast upper ridge begins to amplify. Another shortwave trough grazes the north on Saturday but upper ridge keeps any precipitation well north of the forecast area. Temperatures warm a bit on Saturday then more on Sunday as the upper ridge axis centers over the west coast. High temperatures in the valley will range in the mid to upper 70s with an 80 possible in Redding where light north winds provide an extra boost of heat with adiabatic warming. Saturday may see some high cloudiness while Sunday should see mainly sunny skies also adding a little boost to the daytime highs. Overall airmass warms just a touch more on Monday making it the warmest day of the forecast period.
Extended discussion (Tuesday through Friday)
Upper level ridging gradually shifts eastward on Tuesday with most of the area remaining dry and warm. Have just a slight chance of light rain over far northwestern Shasta County as a weak shortwave brushes through Tuesday-Tuesday night.
Computer models are trending toward a more significant wave with a cold front pushes into northwest California Wednesday. With a moisture supply from a Pacific plume, this will bring the potential for precipitation to areas along and north of the I80 corridor through Wednesday, spreading a little further south by early Thursday. Snow levels are expected to be around 8500 feet, so much of the precipitation will be in the form of rain. Rainfall amounts are expected to be highest to the north and west.
High temperatures will be a little cooler for the end of the week, though should remain near to a little above normal.