We may not be getting a White Christmas this year, San Diego, but it will certainly be wet.
Back-to-back storm systems — one fueled by an atmospheric river — will bring rain, gusty winds, chilly temperatures and potentially some light mountain snow to San Diego County this week.
While California comrades to our north saw stormy weather starting as early as Tuesday, the first storm system is expected to reach San Diego County on Thursday.
The second system, a much less powerful one, will move in on Christmas Day.
From Thursday to at least Saturday, “there’s going to be occasional waves of rain making their way through San Diego,” said NBC 7 Meteorologist Brian James.
“Looks like the rain will start Thursday afternoon with the bulk of the rain continuing through the day Friday,” James said. “We’ll probably have some rain taper off as we go through the day on Saturday, but still some showers on the way for Saturday as well.”
The heaviest rainfall will impact San Diego County overnight Thursday into Friday, when the storm fueled by an atmospheric river reaches the region, according to forecasters.
Some parts of the county could receive more than two inches of rain from this storm system alone, the National Weather Service predicted. The mountains could see up to five inches of rainfall.
As for snow, don’t expect much. The areas most impacted will be above 6,500 feet — which we don’t have many of in San Diego — and maybe down to 5,500 feet during the second, lighter storm.
The biggest impacts could come in the form of flash floods and gusty winds that have the potential to down tree limbs or power lines.
A Flood Watch was issued on Wednesday for San Diego County’s coastal areas, mountains and valleys from Thursday evening through Friday morning. The alert warns excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations.
What is an atmospheric river?
An atmospheric river is a portion of the atmosphere that pulls moisture into a type of stream invisible to the naked eye. There are typically about 11 above Earth at any given moment.
Those streams, made up of condensed water vapor, not water, move from the tropical regions near the equator towards the poles.
Each atmospheric river can measure anywhere from 250 to 400 miles wide and can be more than 1,000 miles long, carrying up to 25 times the flow of the Mississippi River, according to NBC 7 Meteorologist Ana Cristina Sánchez.
While atmospheric rivers typically hover around 10,000 feet above Earth, a weather system — like this week‘s storms — can push an atmospheric river towards land, causing heavy downpours.
Atmospheric rivers, most common during the fall and winter seasons, play a major role in California‘s rain season. 25-50% of our state‘s annual precipitation is produced by atmospheric rivers. Rain and snow amounts can vary widely depending on the exact location, timing and moisture content.
How will this storm affect my holiday travel?
The short answer: you’ll likely be impacted.
The National Weather Service said hazardous travel is possible, particularly on Wednesday through Friday when rainfall will be at its heaviest across California — and will potentially cause flooding.
“Flooding and hazardous roadways are the main concern with this storm system. Please plan ahead and use extra time when making those holiday travel plans!” the NWS wrote on Twitter.
If you do plan to travel during the storm, California’s emergency operator has some tips on what to keep in your emergency car kit — from a flashlight to a hand-crank radio that can pull in weather radio stations. Check out their list here.