February 21, 2020 – Dry except a slight chance of sprinkles or light showers, mainly over the Sierra Nevada, south of Highway 50, later today into Saturday. Light showers also possible over the mountains, north of I-80, Sunday. Above normal daytime temperatures continue.
Closed upper low centered near 32N 129W attm is spreading considerable amount of mid to high level cloudiness across interior NorCal. Low progged to slowly progress towards the coast today into tonight, tracking across SoCal Saturday. As low approaches, diffluent flow aloft increases over southern portions of our Central Valley and Sierra Nevada as area of 7H negative omega spreads northward. Light model QPF depicted over portions of the Sierra Nevada late afternoon into tonight. Variable cloudiness expected today with a decreasing amount from north to south throughout the day. High temperatures this afternoon expected to be slightly warmer with lower 70s for the Central Valley and mostly 50s and 60s for the mountains and foothills.
Upper low center progged near KSBA by Saturday morning, then tracks across SoCal through the day. Sprinkles possible in the Northern San Joaquin Valley tomorrow, however dry subcloud layer will most likely result in virga. Best chances for light measurable precip looks to be over the Sierra Nevada, south of Highway 50. Highs Saturday forecast to be within a few degrees of todays max temps.
Shortwave ridging builds inland behind the low tomorrow night and quickly moves through. Frontal system follows 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 Sunday with locally breezy conditions as weak front moves through.
EPAC builds inland behind the front resulting in locally breezy north to east wind Sunday night into Monday. Dry weather prevails for most of next week under high pressure. Warming daytime temperatures, to upwards of 15 degrees or so above normal, expected Tuesday.
Extended Discussion (Tuesday through Friday)
Warm and dry weather is expected through the extended period as eastern Pacific ridging builds over the region. The ridge axis moves across on Thursday, bringing the warmest forecast high temperatures, 10-17 degrees above normal. For the Valley, this means highs in the mid to upper 70s. While very warm for this time of year, these highs should fall short of records, which are mainly in the low 80s.
North to east winds continue into through through the week, but are not expected to be strong and and will gradually decrease each day. Euro ensembles suggest gusts around 15 to 20 mph for the Valley, with deterministic models a little lower. These winds will continue to dry out vegetation and decrease snowpack in the mountains.
Confidence remains high on dry weather persisting through the end of next week, leaving February a dry month for many locations, including Sacramento. The next potential for precipitation looks to be in early March, and even that looks very uncertain at this point.