Hydrometeorological Discussion National Weather Service / California Nevada RFC / Sacramento CA 830 AM PST Sat Dec 27 2025 ...RETURN TO DRY PATTERN AS ANOMALOUS RIDGE BUILDS ACROSS THE WEST... ...POTENTIAL FOR PRECIPITATION RETURN LATER IN THE WEEK AS MULTIPLE SYSTEMS APPROACH THE COAST... .METEOROLOGICAL CONDITIONS (SAT AM - FRI AM)... A return to a dry pattern is anticipated over the weekend with remnant light shower activity over the next several hours. Any shower activity is expected to be light and spotty. An anomalous ridge will begin building across the West as the current system continues exiting the region forming a surface high off the coast of Oregon and NorCal bringing several days of dry weather across the region. This ridge aloft and surface high will begin to weaken around Wednesday and multiple systems will begin approaching the forecast area. As the ridge weakens, a system off the coast of the Baja Peninsula begins to approach from the south as another frontal system off the PNW coast begins to dig southward. Guidance currently disagrees quite substantially on the phasing of these two systems which creates considerable uncertainty in the resulting precipitation over California beginning Wednesday. Precipitation over southern California may begin as early as Wednesday as the northward propagating low begins extending a plume of higher PWAT values inland across the southern California Bight. This precipitation may begin spreading northward as the low continues shifting to the north and interacts with the frontal system moving inland off the PNW and NorCal coast, increasing precipitation chances across California through Friday. Morning forecasts generally followed guidance from the NBM and WPC, spreading over an inch of accumulation over the Transverse mountains and Big Sur coast in the 3-day window ending 12Z Friday. Accumulations further north are currently lighter with 0.5 to 1.0 inch forecast for the higher elevations of the Sierra and Cape Mendocino. Generally <.25 inches over lower elevations throughout the Central Valley. Expect accumulations to be adjusted as guidance is updated and the event approaches. Freezing levels are expected to rise substantially over the coming days under the anomalous ridge to >12k feet before lower under the uncertain pattern change beginning Wednesday. Please Note: This product may NOT be routinely updated. Please refer to the following product issued by the CNRFC www.cnrfc.noaa.gov/Daily-Briefing for a graphical summary of weather and hydrologic conditions. |