A series of warm atmospheric rivers continues to bring periods of moderate to heavy rain to the San Joaquin Valley, the foothills, and the mountains during this week of Christmas.
The prolonged period of rain and excessive rainfall will bring the risk of flooding to each of these locations.
The National Weather Service has issued a Flood Watch for the Mother Lode, the Sierra Nevada, Yosemite National Park and the northern San Joaquin Valley through Friday afternoon. A Flood Watch will also go into effect for the Mariposa County foothills and the central San Joaquin Valley, from Tuesday afternoon to Friday afternoon.
Heavy runoff will result in rises and possible flooding along area rivers. Small streams and creeks may rise out of their banks. Flooding may occur in low-lying, poor drainage, and urban areas. Mudslides and rockslides may occur in mountain and foothill areas. Low-water crossings may be flooded.
Debris flows are not expected over recent burn scars, but you should anticipate enhanced runoff in or below the scars.
Monitor later forecasts and be alert for possible Flood Warnings. Those living in areas prone to flooding should be prepared to take action should flooding develop.
As far as snow, a Winter Storm Warning is in effect for Yosemite National Park (above the Valley floor) through 4 PM Friday. Additionally, a Winter Storm Watch has been issued for the western slope of the northern Sierra Nevada from Tuesday evening until Friday morning.
Heavy snow is forecast.
Snow levels will remain around 8,000 to 9,000 feet today, then drop to 7,000 to 8,000 feet through Tuesday, and lower to 6,000 feet by Thursday, Christmas Day.
Snow accumulation amounts may range from around one foot at 5,500 feet, up to three to eight feet above the 6,500 foot elevation. The higher you go, the more the snow.
The winds may gust as high as fifty-five mph. Such gusty winds could cause tree damage.
Expect dangerous travel conditions with chain controls and road closures possible. There may be low visibility due to combination of wind and heavy snow. Travel could be very difficult to impossible. If you must travel, keep an extra flashlight, food, and water in your vehicle in case of an emergency.
