Usually, when Santa Ana winds hit Southern California, all of the greater Los Angeles region has to buckle down and prepare for a blustery day of swaying trees and leaves everywhere.
But while strong winds blowing in from the north buffeted parts of the Inland Empire throughout the day Thursday, the wind slackened considerably in other areas.
That’s because a pattern of high pressure over the Great Basin — the massive area of watersheds starting north of the Mojave Desert and extending all the way into Oregon and Idaho — lost significant strength throughout the day, said Casey Oswant, a meteorologist with the National Weather Service in San Diego.
“Overall, the wind has less energy to it,” she said.
“The wind is always going to want to blow from high pressure to low pressure, so the bigger the difference between those high and low pressure systems, the stronger the wind will be. Because the high pressure system is now weakening, there’s less of a difference in pressure in between those systems.”
That resulted in strong winds in the morning followed by more localized wind patterns that became far more diffuse over the rest of the area.
The winds blowing in from the Great Basin were still strong at their most concentrated points: the Cajon and San Gorgonio passes in San Bernardino County. Effectively, those passes acted as wind funnels blowing strong gusts over the Inland Empire communities just to the south. But without enough power behind them, the winds slackened over Los Angeles and Orange counties.
A Weather Service wind advisory remained in effect for most of the region until 4 p.m.
The strongest local wind gusts got up to around 65 miles per hour, according to the Weather Service: In Rancho Cucamonga at 3:50 a.m., and in Chino Hills at 7:10 a.m.
Trabuco Canyon saw wind gusts of around 54 miles per hour at 4 a.m.. And Murrieta and Lake Elsinore felt gusts of 35 miles per hour at 4:50 a.m. and 2:30 a.m., respectively.
Jurupa Hills was still feeling wind gusts of around 44 miles per hour at 10:30 a.m.
The winds were much stronger near the San Gorgonio Pass later into the day.
Beaumont saw wind gusts up to 47 miles per hour until 11 a.m. So did Banning, at around 37 miles per hour.
“The bottom of the San Gorgonio pass, that’s just a windier area,” Oswant said. “Even when we have these weaker wind events, it’s always a little bit windier there.”
Source: Orange County Register