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February 14, 2019 – Strong storm event continues to bring widespread precipitation to the region. Snow levels will lower again this afternoon with heavy snow returning to the mountains. Local flooding with ponding on roads and rises on streams and rivers possible today. Periods of wet weather continue into the weekend.

Discussion

Warm front presently over the central Sacramento Valley continues to move only very slowly to the north. There’s a big temperature gradient across the front with lower to mid 60s in the Sacramento area and lower 40s in the Chico area. Strong southerly winds have been going all night south of the front where winds have been gusting to 35-45 mph.

Moderate to heavy precipitation has been focused overnight along the front to the north of Sacramento with more scattered rain to the south. Rainfall amounts since Wednesday evening have been around 1/2 an inch to an inch in the Sacramento Valley north of Sacramento with 1 to 3 inches across the surrounding foothills and mountains.

987 mb surface low presently just off the northwest coast of California forecast to move up into western Oregon this morning (taking the warm front with it up into far northern California) while the cold front moves ashore. The gusty southerly winds are then forecast to work their way up the Sacramento Valley as surface gradients tighten and better mixing develops behind the cold front. Strong southerly winds will continue in the valley and foothills into early Friday with gusts of 45-55 mph.

Cold front pushes inland this morning and is forecast to reach the northern Sierra around midday. Widespread precipitation is forecast to taper in the valley behind the front this morning, but will continue across the northern Sierra. Snow levels are forecast to drop to around the pass levels around noon, and to below 5000 feet by mid-afternoon.

It looks like another heavy snow event shaping up for the northern Sierra west slopes into Saturday with lowering snow levels, and steeper lapse rates with more favorable upslope flow supporting heavier snowfall rates. Current forecast is for around 4-5 feet of snow accumulation at KBLU (Blue Canyon) through early Saturday.

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Potential for thunderstorms from late morning into the afternoon in the increasingly unstable environment post-front. Small hail and strong winds are the primary threat. However, surface troughing forecast in the lee of the Coast Range may allow enough backing of low-level flow in the Sacramento Valley to allow for persistent convection to develop rotating updrafts with potential for a few funnel clouds or perhaps a weak tornado.

Wet and cooler pattern will continue into the weekend as several disturbances drop down from the northwest bringing showers and adding to the snowpack in the mountains.

Extended Discussion (Monday through Thursday)

Main upper trough will be located over the southwest US leaving NorCal dry by early Monday. A moderate pressure gradient across the Sierra Monday and Monday night will bring breezy north winds to the area with high temperatures continuing to be below normal. Upper ridging Tuesday will keep one more day of dry weather before models depict the potential for another system Wednesday. Small chances for precipitation continue from Wednesday on, but models are still quite a bit different leading to low confidence with any precipitation chances for mid-week.