Unpredictable Bay Area weather now likely to stay mostly dry through weekend

In their initial analysis, weather forecasters anticipated a decent amount of rain might fall upon the Bay Area as the weekend beckoned.

Call it a slump as far as forecasts go. In mid-November, a forecast that several systems would bring significant rain wound up bringing considerably less.

“Yeah, things have not been going as predicted,” National Weather Service meteorologist Matt Mehle said Friday. “There’s a few things at play on that.”

The main one, he said, is that this system and the others contained “cut-off lows, an area of low pressure that’s cut off from the main flow of the atmosphere. It can dissolve or go in its own direction. And that’s what we’ve been seeing.”

He said that such patterns in a weather system don’t happen all the time but that they aren’t too unusual, either.

As a result, Mehle said the systems are passing south through the area but too far west of the coast to drop heavy rain.

“We are on the far eastern edge as far as precipitation,” Mehle said.

The primary area where forecasters believe rain may fall heavily is close to the California-Oregon border. Rain also could fall in areas of the North Bay, but Mehle said it will be “very light and the showers will be very scattered.”

That rain likely will fall late Friday into early Saturday morning, forecasters said.

No measurable rainfall is expected in the South Bay or East Bay, though there could be a bit of drizzle, according to forecasters.

Temperatures are expected to be about average for the first week of December, according to Mehle. Temperatures throughout the region are expected to top out in the low-to-mid-60s. The overnight lows will fall into the mid-40s.