Wind Forecast for L.A. Fires Was Weaker Than Expected, but Could Pick Up Wednesday

Weather Service meteorologists make their forecasts based on a combination of current conditions, historical events and computer weather models. They take all this information in and then forecast what they think is the most likely outcome. There are always outliers, conditions that could occur but are less likely.

Sometimes, a storm will overperform the forecast, and sometimes it will under perform. In meteorology, both eventualities are considered “busted forecasts.” While forecasters who predict an especially extreme event might be happy if the conditions aren’t as bad as they had predicted, they know that if the forecast is off by too much, people will trust future warnings a little less.

James Brotherton, a meteorologist with the Weather Service in Los Angeles, said he would much rather have a forecast be wrong if it meant there was “less pain and suffering.”

Ahead of this cycle of winds, forecasters put another “particularly dangerous situation” warning in place from 4 a.m. Tuesday through noon on Wednesday, as they feared more strong winds would help fuel existing fires and possibly spark new ones. But by early Tuesday afternoon, the winds were proving to be less strong than expected, and the Weather Service dropped the warning for the rest of the day. The move was temporary, and another “particularly dangerous situation” warning will be in place from 3 a.m. to 3 p.m. Wednesday.

Ryan Kittell, another forecaster in the Los Angeles office, compared it to someone filling out an N.C.A.A. bracket every March. “Even if you’re the best, at some point you won’t have a forecast verify as you would like,” he said.

The “particularly dangerous situation” designation is still a relatively new tool, Mr. Kittell said. Tuesday’s forecast was always right at the line between high level and not, and the office opted to use the stronger warning because of the ongoing fires across the region, he said.

Robert Clark, a fire behavior analyst for Cal Fire who is working on the Palisades fire, was relieved Tuesday’s winds weren’t as powerful. The fire didn’t grow overnight, and quieter weather was allowing crews to extinguish fire in pockets of smoldering landscape and vegetation.

While conditions have improved, Mr. Clark said he was most concerned about the forecast for the Santa Ana winds to pick up again Tuesday night into Wednesday.

“And then we’re looking out to the future to see what happens with the weather forecast with an additional round of Santa Ana winds possible next week,” he said.