March 18, 2019 – Dry and mild weather today and Tuesday. Precipitation chances return Tuesday night with another system possible late week.
High clouds associated with a weakening trough extend across central California (and the southern portion of the forecast area) with clear skies to the north across most of NorCal. Current temperatures are mostly milder compared to 24 hours ago and generally range from the mid 20s to lower 30s in the mountain valleys to the 40s and lower 50s elsewhere.
The dry and mild weather pattern from the weekend will continue today and Tuesday as the omega block holds over the West. Today will likely see the warmest temperatures this week with highs in the valley expected to be in the mid to upper 70s. Highs are expected to cool a bit over the valley on Tuesday as the leading short-wave approaches from off the coast inducing a return of onshore flow.
The block shifts east by Tuesday night allowing cooler and more unsettled weather to return for the second half of the week. Convective precipitation will bring varying amounts of QPF to the area Tuesday night through Wednesday night. Around 1/4 to 1/2 inch is expected in the valley with up to an inch over the mountains. Snow levels will lower to around 5-6k ft and 5-10 inches of snow will be possible along the crest of the northern Sierra leading to some travel impacts over the higher elevations.
At this point, a relative break in showers is expected on Thursday under short-wave ridging ahead of a stronger system late in the week.
Extended Discussion (Friday through Monday)
Ensemble and model guidance continue to point towards wet weather for the coming weekend as an upper level low sweeps over the region. Valley rain and mountain snow look likely at this time; however, long range models are starting to struggle with precipitation amounts. Snow levels seem to remain fairly consistent and will likely start off around 5500-6500 feet before falling to roughly 4500-5000 feet Saturday afternoon. The low is projected to exit the region on Sunday which could bring us a brief break in precipitation, but we have decided to continued PoPs in on Sunday as the foothills and ridges may see lingering showers.