Atmospheric River Storm Expected To Arrive In Lamorinda Overnight

LAMORINDA, CA — Another atmospheric river-driven storm is expected to hit Contra Costa County and the Bay Area in what the National Weather Service is calling a "direct threat to life and property."

The expectation of another round of heavy rains prompted the NWS to issue a regionwide flood watch scheduled to go into effect at 10 p.m. Monday and continue through 4 a.m. Wednesday.

Widespread and potentially significant wind impacts are also expected with this storm. With wind gusts of up to 50 mph in the valleys and up to 60-70 mph in higher elevations expected, the agency also issued a high wind warning scheduled to go into effect at 11 p.m. Monday and continue through 5 a.m. Wednesday.

A bulletin issued by the agency Monday morning said that highly saturated soils paired with elevated river and stream levels made more water-related impacts a “sure bet" during the storm which is expected to bring "notable and potentially long-lasting impacts to our area."

The bulk of the rain is expected after 1 a.m. Tuesday.

Lamorinda could see nearly 2 inches of rain Monday evening through Wednesday morning, with .61 inches expected overnight Monday into Tuesday, and another 1.21 inches during the day Tuesday.

In addition to flooding, the potential for shallow landslides and debris flows will also increase with travel impacts likely to develop starting Monday night, the weather service said, adding that hazardous travel conditions are likely to exist into at least Wednesday and potentially beyond for some areas.

"Postpone travel if possible and remember to NEVER drive through flooded roadways," NWS said. "Turn around, don't drown!"

NWS said that while plenty could be written about the incoming atmospheric river from a meteorological perspective, "brevity" was probably for the best considering the expected impacts.

"This is shaping up to be a significant system with the potential for wide-reaching and long-lasting impacts," NWS said. "Now is the time to prepare. Get gas for generators, clean storm drains and gutters, tie down or move loose objects inside. Make sure you have extra supplies, food, and necessary medications in case roads are closed or power outages last for several days. Pack a 'go bag' to help evacuate quickly if you live in a flood-prone location. Avoid unnecessary travel and stay safe!"

A drying trend on Wednesday into Thursday should allow a brief window for storm cleanup. Rain chances look to return by Friday into the weekend.

Here is the National Weather Service's current seven-day forecast for Lamorinda:

Monday Afternoon
A 40 percent chance of rain. Mostly cloudy, with a high near 61. South southwest wind around 18 mph, with gusts as high as 23 mph. New precipitation amounts of less than a tenth of an inch possible.

Monday Night
Rain. Low around 53. South wind 13 to 21 mph, with gusts as high as 31 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three-quarters of an inch possible.

Tuesday
Rain before 11am, then showers and possibly a thunderstorm after 11am. Some of the storms could produce heavy rain. Steady temperature around 55. Windy, with a south southwest wind 28 to 33 mph, with gusts as high as 44 mph. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible.

Tuesday Night
Showers likely and possibly a thunderstorm before 11pm, then a chance of rain after 11pm. Some of the storms could produce heavy rain. Cloudy, then gradually becoming partly cloudy, with a low around 40. Breezy, with a west southwest wind 21 to 28 mph, with gusts as high as 41 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Wednesday
A 20 percent chance of rain before 11am. Mostly sunny, with a high near 56. West northwest wind 10 to 18 mph, with gusts as high as 26 mph.

Wednesday Night
Mostly clear, with a low around 40.

Thursday
Mostly sunny, with a high near 59.

Thursday Night
Mostly cloudy, with a low around 43.

Friday
A chance of rain. Mostly cloudy, with a high near 57.

Friday Night
A chance of rain. Mostly cloudy, with a low around 44.

Saturday
A chance of rain. Partly sunny, with a high near 58.

Saturday Night
Rain likely. Mostly cloudy, with a low around 45.

Sunday
A chance of rain. Partly sunny, with a high near 58.