Strong, damaging winds are expected to begin in parts of Northern and Central California as early as Sunday evening and are expected to last through Wednesday.
High wind warnings are in effect for more than 30 million people from North Central California to Southern California.
On Sunday evening, a strong high-pressure area will build up in the northwest and through Monday, this high-pressure area will shift to the Great Basin by Tuesday. As this high pressure area builds up, a low pressure area will develop off the southern coast of California.
The proximity and strength of the two systems is important. This is known as the pressure gradient, which is expected to be quite strong and will cause these intense winds to develop early this week.
Winds flow from areas of high pressure to areas of low pressure, so in this case the wind is expected to be offshore winds for this event, when the wind moves from land to sea. Locally in various parts of California, these wind events are often referred to as “‘Diablo winds”, “Mono winds” or “Santa Ana winds”.
Timing
Areas in Northern and Central California are expected to experience these strong winds first, arriving late on Sunday and lasting through Tuesday.
The strongest winds through Northern and Central California are expected to develop Monday evening to Tuesday morning.
The strongest winds through Southern California are expected on Tuesday.
Winds this strong can lead to downed trees and power lines, power outages, and potentially widespread critical weather events in a fire across much of the state.
Fire brigade
Typical firefighting conditions in areas of Southern California are fueled by a combination of above average temperatures, low humidity, dry vegetation and high winds. Developing low pressure off the coast of Southern California could limit some of these factors, resulting in lower temperatures and higher humidity levels. As a result, the weather conditions during a fire at the beginning of this week may be somewhat limited.
However, many locations in Southern California, including Los Angeles, have not had any measurable rainfall since late December, meaning the vegetation in the region has had more than two weeks to dry out.
Southern California has also seen record heat in recent days, in addition to increasing drought in the region.
When you take into account dry vegetation, drought and strong winds, it only takes one spark to start a fire and spread quickly. The Storm Forecast Center has not ruled out the possibility of critical fire conditions, especially on Mondays.
The SPC also said these humidity readings could drop in the teens in some locations due to descending winds – dry winds that flow east to west through California mountain passes – which could lead to a few hours of critical fire conditions on Monday afternoon.
However, this low pressure area will bring some much-needed rain and snow to parts of the Southwest in the coming days, which will help alleviate the widespread drought in the region.