February 20, 2020 – Dry except a slight chance of showers over the Sierra Nevada late Friday and Saturday and over the mountains north of I-80 Sunday. Above normal daytime temperatures continue.
Discussion
Baroclinic cirrus spreading over interior NorCal attm ahead of associated frontal zone near 128W. Upper low nearing 130W is forecast to dig today into Friday, then shift inland Saturday along with weakening baroclinic zone. NAM-12 spreads some light QPF over the Sierra Nevada, south of Highway 50, late Friday and Saturday invof deformation zone as upper low tracks across SoCal. POPS remain low as other models suggest bulk of precip threat remains south of the CWA. Variable amounts of mid to high level clouds traverse interior NorCal over the next 48 hours. Highs today expected in the upper 60s to around 70 for the Central Valley, warming into the lower 70s Friday.
Above normal daytime high temps continue over the weekend under short wave upper ridging. Frontal system moves into the PacNW Sunday with southern portions brushing across NorCal. Boundary could trigger a few isolated light mountain showers, mainly north of I-80. Minor cooling with locally breezy conditions over higher terrain Sunday as front moves through.
Extended Discussion (Monday through Thursday)
Eastern Pacific high pressure ridging builds in behind a departing shortwave on Monday. This will bring breezy north to east winds into early Wednesday, along with warming and drying. Ensembles are not projecting strong gusts at this point, though, mainly in the 20s mph for the Valley.
High temperatures in the Valley are expected to be in the low 70s Monday, reaching the mid 70s in some spots by Tuesday and Wednesday. Above normal daytime high temperatures are expected through the extended period. Confidence is high on dry weather persisting, with some model runs projecting just a weak system brushing by to the north on Thursday.