First of Holiday Storms Drenches San Diego County, Thunderstorms Aim for Beaches

An atmospheric river has its sights set on Southern California and began delivering rainfall to San Diego County late Thursday

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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 — brought rain, gusty winds and chilly temperatures to San Diego County.

While California’s comrades to our north saw stormy weather starting earlier in the week, the same storm system finally reached San Diego County Thursday afternoon.

“This rain is going to continue to move this morning," NBC 7 Meteorologist Sheena Parveen said in her forecast on Friday. "The heaviest rain is going to be this morning and then it’s really going to improve later this afternoon.”

She added the heaviest rain will continue to hit the region before 10 a.m. and showers will begin to taper off after 2 p.m.

The National Weather Service warned beachgoers that a series of thunderstorms with the potential for lightning will be moving through San Diego County's beaches through 9 a.m. Anyone who hears thunder is urged to head indoors and seek immediate shelter to be safe.

NBC 7’s First Alert 7 Doppler radar showed widespread rain across the county Thursday evening that continued through Friday morning.

"The rain will first be light, then moderate, then pockets of heavy rain. That will continue through the overnight hours," NBC 7's Meteorologist Dagmar Midcap said on Thursday

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.

Click here for a closer look at the precipitation totals in the region brought by this storm.

A wind advisory will remain in effect through 6 p.m. Friday, with southwest winds at 25- 35 mph and isolated gusts with the potential to reach up to 60 mph. A flood watch is in effect for most of the county until 12 p.m. Friday.

NBC 7's Jackie Crea spoke with some San Diegans about the winter storm.

Possible Road Closures Ahead of Storm in Mission Valley

The San Diego River is "expected to crest and road flooding will be imminent," city officials said in the announcement.

City officials said San Diegans can expect the following roads to close at any time during the storm:

  • Camino De La Reina between Camino De La Siesta and Avenida Del Rio
  • San Diego Mission Road between Fairmount and Caminito Yucatan
  • Mission Center Road between Hazard Center Drive and Camino De La Reina
  • Camino Del Este between Station Village Drive and Camino De La Reina
  • Qualcomm Way at Rio San Diego Drive
  • Ward Road at Camino Del Rio North

NBC 7 spoke with San Diego Police and confirmed as of 6 p.m. Thursday, only 1100 Fashion Valley Road is closed between Riverwalk Dr. and Hotel Circle North. These roads could potentially be impacted by another storm aiming for the county on Saturday.

As for snow, not much was forecasted. 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.

Flash flood watch

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 that excessive runoff may result in the flooding of rivers, creeks, streams and other low-lying and flood-prone locations.

Parveen said Thursday’s rain will taper off Friday evening and dry conditions will settle in for a brief period of time before another system moves in.

“Friday morning, we should be dealing with a very large amount of rainfall through the county, some of it heavy through the afternoon,” Parveen said. “Some of that rain could still be heavy and starting to taper off Friday night, and then more rain in the forecast on Saturday.”

The second system, a much less powerful one, will move in on Christmas Day.

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?

San Diego County’s first winter storm is impacting holiday travel for Christmas Eve. NBC 7’s Ashley Matthews has insight to help you maneuver the challenges.

The short answer: You will 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 Tweeted.

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 the list here.

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