California in for wet, white, potentially wild Christmas as Pineapple Express storm looms

"A powerful Pineapple Express storm could deliver a wet, white and potentially wild Christmas to California, with the possibility of snow in the Sierra Nevada and plenty of rainfall across the Southland. Although the forecast is still coming into focus, the incoming atmospheric river system is shaping up to be the strongest in years to hit the Los Angeles area on the holiday - and threatens a soggy slog for those hitting the road to visit friends or family."

"The most likely scenario for Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties involves "high amounts" of rain: 2 to 4 inches on the coast and in the valleys between Dec. 24 and 26, according to Robbie Munroe, meteorologist with the National Weather Service office in Oxnard. There's a 50% chance of that scenario coming to pass. There's also a 30% chance of more moderate rainfall, 1 to 2 inches on the coast and in the valleys, as well as 10% chance of "very high" amounts, 4 or more inches, in those areas."

"The last time it rained on Christmas Eve or Christmas Day in downtown L.A. was in 2021, when 0.83 inches fell over the two days. It's still unclear whether this storm will be naughty - with torrential downpours intense enough to cause flooding and mud or debris flows or nice, with gentle rainfall spread out beneficially over a period of days. "Even if we see really high totals, impacts might still be more on the minor-to-moderate side," Munroe said during a briefing Wednesday."

A Pineapple Express atmospheric river is expected to impact Southern California around Dec. 24–26, bringing widespread rain to coastal and valley areas and potential snow in the Sierra Nevada. Forecast scenarios assign about a 50% chance of 2–4 inches on the coast and in the valleys, a 30% chance of 1–2 inches, and a 10% chance of 4+ inches. Historical data show measurable Christmas rain in downtown Los Angeles in 2021 (0.83 inches) and the last greater-than-2-inch Christmas total in 1971. Heavy downpours could cause flooding, mud and debris flows and disrupt travel.

Read at Los Angeles Times