As if ordered by Santa, frigid winds brought a white Christmas Eve to the mountains of San Diego County, with some snow flurries reportedly even making a brief appearance in such unlikely spots as La Mesa, Poway and the San Carlos area of San Diego.
The snow came as the county was girding for possible record cold Christmas night. San Diego's downtown high temperature was 55 degrees Thursday, just 3 degrees short of the record low-high temperature of 52 degrees, set on a Christmas eve in 1879. By 10 p.m. Christmas Eve the official temperature at Lindbergh Field had dropped to 42 while it was 34 in El Cajon. Snow fell all day Thursday in Pine Valley and Alpine, residents, while their were unconfirmed reports of snow flurries in low-altitude locales such as El Cajon, La Mesa, San Marcos, Poway and Escondido, according to National Weather Service forecaster Wilbur Shigehara.
The frigid air is expected to send overnight low temperatures plunging to near record lows tonight, according to forecasters.
Snowflakes in Jamul
Thursday's storm dropped flakes as far down as Jamul, which is at about 1,000 feet, according to Shigehara, "although snow wasn't sticking there. As soon as it landed it melted."
Thursday's storm also dumped about an inch of snow on Mount Laguna. The basic snow level remains at about 1,500 feet, he said.
Still, county residents may get a white Christmas in their own back yard, as a thin layer of frost is expected to cover the county today, "clear up to the water's edge," Shigehara said.
Biting temperatures will continue to chill the county, although sunny skies will abound.
"We're really going to have to bundle up over the next few days," he said. "Temperatures along the coast could drop down to 28 degrees tonight, and to 23 degrees in the inland valley areas."
Freeze Warning Remains
A freeze warning issued for the entire county last Wednesday will stay in effect until Saturday night, according to Shigehara.
"We're expecting freezing conditions to bottom out tonight. In areas where we produce crops, temperatures could plunge to 18 degrees in some places," he said.
Growers were also warned about the possibility of "black frost," which means a "lack of frost" accompanying freezing temperatures, according to Shigehara.
"People seem to think if they don't see frost, it's not that cold!" he said. "But it can be."
White frost is what we see forming on a lawn, or crystallizing on a car because, according to Shigehara, there's moisture in the air.
'White, Puffy Stuff
"This is the white, puffy stuff we see when temperatures hit 32 degrees or lower. But, we still can be freezing and not see the white stuff," he said.
When there is no visible frost formation, that's an indication that there's little moisture in the air, according to Shigehara. When we have dry cold air we have black frost, or no frost, he said.
Low temperatures are expected to hit about 19 degrees in Bonsall; 22 in Valley Center; 21 in Escondido; 20 in Campo; 25 in Fallbrook; 31 in Vista; 24 in San Pasqual; 22 in Rincon. If growers aren't prepared, these below-freezing temperatures are capable of causing widespread crop damage, according to Shigehara.
"As early as Monday the National Weather Service put out a warning to growers, so they've been very lucky. They've had enough time to get ready," he said.
"It's also a good idea for people with potted plants to bring them indoors, close to their homes," he said.
By Saturday, temperatures should rebound slightly, with overnight lows not expected to dip below 23 degrees, he said.
"Sunday lows shouldn't drop below 26 in the agricultural areas," he said. Localized cold, dry Arctic winds from 15 to 25 m.p.h. will whip through coastal and inland valley areas today. "Mostly, we'll be breezy with a chill in the air," Shigehara said. "By Saturday, winds will calm down."
High temperatures along the coast will range from 50 to 55 today with lows from 28 to 38. Saturday highs will be in the 55- to 60-degree range, with lows from 30 to 39. Highs will climb to the low 60s Sunday, with lows from 35 to 42, according to forecaster Dan Bowman of WeatherData, which provides forecasts for The Times.
Surf is at three to four feet, with ocean temperature near 57 degrees.
Low temperatures from 23 to 33 are expected in the inland valley areas today, with highs from 50 to 55. Saturday lows should moderate and range from 28 to 35, with highs in the 55 to 60 range. Sunday lows will be in 30s, with highs from 57 to 62.
All storm activity is expected to subside in the mountain areas today, giving way to clear, sunny skies, Bowman said. A wind advisory will remain until Saturday, with winds gusting up to 40 m.p.h. today. High temperatures for the mountains today and Saturday will range from 25 to 35, with lows in the 10 to 20 range both days. Highs Sunday should be in the low 40s, with lows from 15 to 25.
Desert areas will also experience clear blue skies through Sunday, with highs from 51 to 58 today, and lows in from 25 to 35. Saturday and Sunday, temperatures will increase slightly and range from 58 to 65, with lows in the 30s.