The weather pattern that has sent a surge of warm, tropical moisture flowing into San Diego County in recent weeks has set a new record: the region has seen its wettest summer since record keeping began more than 100 years ago. Nearly 3 inches of rain have doused Lindbergh Field since July; the average is less than a quarter of an inch.
“It has all been backwards in extremes,” said Alex Tardy, a meteorologist with the National Weather Service. “In January through April we had less rainfall than we did this summer. It has just been totally flip-flopped.”
The historic rains and hot temperatures are being fueled by the exceptionally warm ocean water off the West Coast, as well as monsoonal moisture over Baja, and the 16 tropical storms and depressions that have passed through the Eastern Pacific Ocean.
But the weather pattern is about to shift and open the door to hot and dry Santa Ana winds, said Tardy.
“This is the time of year that we expect to see Santa Anas,” Tardy said. “Even though we’re expecting an El Niño this winter, a strong one, in October and November we’ll still see Santa Ana winds developing as the storm track starts getting active over our region.”
Tardy said El Niño is expected to begin pushing rains over the region in November.
“Until then, we’re going to have to deal with at least a couple of Santa Ana wind events,” Tardy said.
"The issue is getting from the tropical air mass that we’re in now, to the Pacific air mass, which is in the wintertime," he said. "The transition in between there is the critical time. We’re hoping this year, because of all the tropical moisture and because El Nino’s brewing out there that that window will be much smaller."
In the meantime, the tropical rains will dampen the fire risk, he added.
"Our fuels are very dry still from the four year drought," Tardy said. "But what does that rain do? It buys us a couple weeks. Unfortunately, there will still be a high fire threat."
