Dry and warmer today and Saturday, another storm arrives Sunday

April 13, 2018 – Dry weather and warmer today and Saturday, but more rain and accumulating mountain snow is expected to return by Sunday into early next week.

Discussion

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Dry with a warming trend Today and Saturday as upper ridge builds over NorCal. Temperatures for valleys will warm into the low and upper 70’s. The dry and warm conditions will be brief, as another cold and wet system drops south from the Gulf of Alaska. Current forecast shows best precip chances moving in Sunday afternoon and night with snow levels starting around 5500 feet falling to 4000 feet late Sunday night.

The heaviest Sierra snow looks to be Sunday evening into the early morning hours at which time 6 to 12 inches and locally 18 inches could fall. Sunday evening and overnight travel over the mountains is likely to be hazardous with chain controls possible. South winds are likely to become breezy during the afternoon with a few gusts to 35 mph over the valley much stronger over the mountains where a few gusts to 55 mph will be possible, especially over ridgetops.

Mountain snow showers and valley showers and isolated thunderstorms continue Monday, as cold core sweeps through NorCal with causing an unstable atmosphere. Valley rainfall amounts are currently forecasted to much lighter than last week storm with from 0.50-1.00 inch expected at this time.

Extended discussion (Tuesday through Friday)

Shortwave ridge of high pressure will bring partly cloudy skies and a bit warmer afternoon high temperatures across northern California Tuesday with a chance for a stray shower across the Sierra. The next widespread chances for rain and mountain snow return Wednesday and Wednesday night as the next disturbance approaches the forecast area. Snow levels are expected to be around 3500 feet with a few inches of accumulation for the mountain passes through Thursday.

Early indications for late next week show a return of dry stable air aloft with afternoon high temperatures returning to near normal.