Quite update this evening. A cold upper low is retrograding and deepening over OR tonight and sliding south to offshore NorCal by tomorrow afternoon. Convective precipitation will increase over the next 24 hours across the northern 1/2 of the state along with lowering snow levels into the 1000-1500 foot range. Heavier convective elements could produce frozen precip (hail, grapuel, wet snow) briefly down to sea level. Isolated thunder is possible, esp. by Tuesday. Significant and even locally heavy rainfall can be expected in some areas. Heavy snowfall at very low elevations is possible, and a Winter Storm Watch is in effect for higher parts of the Bay Area. Cold and showery weather will affect the entire state by Tuesday as 850 mb temps drop below zero from OR to MX. Although not as cold as in some previous progs, it’s still going to be a week of fairly dramatic weather. A second system, much like the first, will bring another round of widespread convective precipitation and low snow levels by Thurs/Fri to the entire state. We do need to keep an eye on the potential for either of these lows retrograding even further offshore and tapping a tropical plume that will be present. If this occurs, we’ll be talking about an entirely different type of storm. More cold and unstable air is forecast to dive southward from Canada next weekend, potentially bringing even lower snow levels than the first event. Stay tuned–and enjoy the interesting weather courtesy of La Nina…
