High Wind Warning For North Bay Hills; Gusts Exceeding 70 MPH

SAN FRANCISCO (CBS SF) -- Strong off-shore winds began howling through the North Bay hills Tuesday, triggering a high wind warning from the National Weather Service.

The warning carries the threat of toppled trees and large limbs, downed power lines and a threat of wildfires in the rapidly drying out hillsides.

January ended as the tenth driest in San Francisco history as the drought-busting promise of the December rains continued to evaporate and the hillsides dry out.

The monthly Sierra snowpack measurement on Tuesday was expected to be at a high level but it has now dropped into the 90 percentile after near historic snowfall in December.

The winds were being caused by a "robust pressure gradient" developing between an area of increasing surface pressures over the central Great Basin and an area of low pressure along the California coast, forecasters said.

"Strong to locally damaging wind gusts and elevated fire weather concerns are the primary hazards," NWS forecasters said of the wind warning and advisory in place for the Bay Area until Thursday morning. "The stronger winds should initially reach the North Bay Mountains, East Bay Hills and the Diablo Range. With time these winds should expand into the Santa Cruz Mountains by this evening."

At the higher elevations, the winds will be approaching hurricane force.

"Gusts exceeding 70 mph are likely above 2,500 feet, with 45-55 mph gusts probable down to 1,000 feet," the weather service warned.

As of 7 a.m., the winds were already beginning to pick up. Gusts of 52 mph were clocked at Pine Flat Road in Wine Country, Mt. Diablo hd gusts of 51 mph, Healdsburg winds were at 42 mph and 40 mph in the Oakland hills.

With the winds comes tumbling humidity levels and warmer temperatures. A combination that has elevated the concerns of fire officials. Crews are still in the final mop stages of a rare winter wildfire in the coastal mountains near Big Sur.

"Much drier air will...combine with our limited rainfall (to) contribute to drying fuels across the area," the weather service said. "Expect minimum humidity values to drop into the 10 to 25% range this afternoon with little in the way of overnight recovery. This is especially true in the higher elevations. Elevated Fire Weather concerns are expected today, persisting into mid-week given similar conditions."

Forecasters issued a dire warning during the Big Sur fire.

"It seems as though the long-term drought is acting like a chronic illness where even recent rains and cold winter weather isn`t helping to keep fires from developing," they said.