Potent atmospheric river targeting Bay Area after balmy holiday weekend

SAN FRANCISCO -- The San Francisco Bay Area's reprieve from the stormy conditions that were ravaging the Midwest and Northeast on Friday will come to an end after a balmy holiday weekend.

A storm system carrying with it a significant atmospheric river was forming in the frigid waters of the Gulf of Alaska and will bring heavy rain into the region beginning late Monday night.

Researchers at Scripps Center for Western Weather and Water Extremes projected the stream to be a Cat. 3-4 on their scale of 1-5.  

"Signals for a potent atmospheric river event early next week continue to show promise as a strong upper jet sets up across the entire Pacific Basin," National Weather Service forecasters in Reno warned. "As this jet draws subtropical moisture northward, a moderate to strong atmospheric river will be possible mainly in the late Monday into Tuesday timeframe." 

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When it comes to rain totals, forecasters, said as much as five inches could fall in some parts of the region.

"We are expecting moderate to heavy rainfall beginning late on the Monday starting in the North Bay, then spreading southward into Tuesday morning, persisting through the day Tuesday," forecasters said. "Forecasted storm total rainfall amounts are trending wetter, with the North Bay and coastal ranges still on track to see the most rain with 2-3 inches and 3-5 inches respectively."

Along with the downpours will come a list of warnings and advisories including flooding in some areas.

"This rain storm raises hydrologic concerns such as roadway flooding and minor mud/rock slides, so if planning to travel be sure to stay up to date with the forecast and use caution on the roads," the weather service said.

But before the storm hits, the weather in the Bay Area looks to be picture-perfect for the holiday weekend. Temperatures will be in the 60s and the skies will be blue.

"Ridge of high pressure will build today into Sunday, bringing pleasant and mild weather today through the holiday weekend," the weather service said. "Temperatures today will be in the upper 50s to low 60s ... Looking to the holiday weekend, temperatures will continue to warm and be ~5 to 10 degrees above climatological normals, with the warmest day on track to be Sunday with highs in the upper 60s to low 70s."