Grim weather forecast for California through early February

The last time it rained in downtown San Francisco was 20 days ago, Jan. 7, and long-range weather forecast models show dry conditions in the coming days, said the National Weather Service.

“I hate to say it, but there’s no rain in 14 days,” said Ryan Walbrun, a weather service forecaster.

If these predictions hold, the San Francisco Bay Area will see no significant rain for more than a month amid what is typically the wettest time of year.

Since Jan. 1, the city has recorded 0.61 inches of rain. If there is no more rain until Jan. 31, Walbrun said San Francisco would end the month at about 15% of normal for January.

“We should be somewhere around 4.25 inches,” Walbrun said, noting January’s average rainfall in SF.

Previous forecasts pointed to a chance of rain on Monday and early February, but the chances have since diminished.

“There’s definitely no rain today through Sunday, then there’s a very weak system on Monday, but I quite frankly think that won’t impact the Bay Area,” Walbrun said. “It could bring a snow shower to the Sierra. Beyond that, at least for the first week of February, there’s no sign of rain. It never looked like a really wet setup, but if that had materialized, it would have brought at least some rainfall.”

Walbrun said the low pressure trough that was expected to sweep through the Bay Area is now expected to impact Montana, Wyoming and Colorado.

The system “has moved east and that’s making all the difference in the world,” he said.

It’s not just the Bay Area that looks dry. Long-range forecast models that had hinted at rain in California in early February now suggest dry conditions.

“Sets now tend to be even drier for early mid-February, so it looks like this won’t represent a significant pattern change for CA,” wrote UCLA climatologist Daniel Swain. Twitter. “Probably cooler for a few days with maybe a few showers (mostly Sierra), but no hydrologically significant precipitation on the horizon.”

The dry conditions are the result of a ridge of high pressure stretching across California. The ridge blocks the jet stream and prevents storms over the Pacific Ocean from reaching California.

“This ridge unfortunately appears to be keeping the region drier for the foreseeable future,” the weather service said in its forecast. “Assuming no more rain for the month, downtown San Francisco will end up with the tenth driest January on record.”

Dale D. Schrum