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Climate and Environment

Coldest Storm Of The Year Expected This Week With Snow And Graupel Possible (And Yes We Will Explain That Term)

A swirling cloud mass is visible over the Atlantic Ocean nearly the U.S. West Coast.
A view of the powerful storm system approaching the U.S. West Coast Wednesday.
(Courtesy NWS)
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Bring out the hand warmers and get ready to be extra careful on the roads. The National Weather Service forecasts a cold, blustery winter storm from Canada heading our way in Southern California starting Tuesday.

This story is no longer being updated

Brace yourself for very windy and much cooler conditions by Tuesday tonight — along with a chance of showers and even snow at low elevations.

"It's going to bring a lot of cold air and a lot of wind," explained Andrew Roarke, a meteorologist with the NWS told us, "looking for 70 mph gusts in the mountains and 60 miles per hour gusts in Antelope Valley, and probably 30 to 40 mph gusts in the valleys."

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By Wednesday, Southern California's mountains will see wind gusts up to 50 mph with afternoon high temperatures dropping to the mid-50s, so it'll be uncomfortable going outside.

NWS officials are warning it will be "the coldest storm of the season, and possibly of the last several years."

Adding: "Snow or graupel may even occur across some elevated valleys!"

The bulk of the rain will start Thursday and that could bring three to four inches of rain across the area.

Travelers should be prepared for possible road closures or delays.

What else you should know

  • Wind gusts are expected to reach gale force speeds.
  • High surf, creating dangerous condition is also expected.

What exactly is graupel?

A man with light-tone skin stands in a parking lot with his face turned up to capture falling graupel.
Our former colleague Kyle Stokes enjoys the graupel falling on Pasadena on Thursday, Feb. 21, 2019 at approximately 2 p.m. Kyle missed the snow so much that he moved back to his home state of Minnesota this year.
(Kristen Muller

You might remember graupel from the last time it fell in Southern California, to the delight of many people, including those here in our newsroom.

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Here's the definition from the National Oceanic and Atmosphere's (NOAA) severe weather lab:

Graupel are soft, small pellets formed when supercooled water droplets (at a temperature below 32°F) freeze onto a snow crystal, a process called riming. If the riming is particularly intense, the rimed snow crystal can grow to an appreciable size, but remain less than 0.2 inches. Graupel is also called snow pellets or soft hail, as the graupel particles are particularly fragile and generally disintegrate when handled.

What's next

Roark told us snow will be as low as 2,000 feet, "which will bring snow to the major mountain passes, perhaps as low as to the foothills in some of the valleys. This precipitation should last through Saturday."

Resort level areas will see up between two to four feet of snow at elevations above 7,000 feet and major mountain passes like the Grapevine and the Soledad Pass off Route 14 to Palmdale will see 5 to 6 inches of snow.

L.A. County winter shelters

[View the document here if the embed doesn't load for you: L.A. County winter shelters]

What to know in a flood watch/warning

Here's an excerpt from our guide to understanding flood warnings:

  • Flood advisories are how the NWS begins to raise the alarm. The goal is to give people enough time to take action.
  • Flood watches are your indicators to get prepared to move.
  • A flood warning is issued when a hazardous weather event is imminent or already happening. When one is issued for your area, you need to get to higher ground immediately.
  • A flash flood warning is issued when a flash flood is coming or in progress. Flash floods are sudden and violent floods that can start within minutes.

Read more: Flash Flood Warnings? Watches? Here’s What You Need To Know

Road closures and conditions

We will be watching the roads closely as the storm moves in and will update you on conditions. We know the Grapevine passing on the I-5 is a perennial issue for drivers when there's snow or high winds, so be sure to check before using that route. Last week CHP officers had to escort traffic through the area.

Authorities also say Soledad Pass along the 14 to Palmdale may see 5 to 6 inches of snow.

The NWS is already warning travelers to be prepared for possible road closures or delays.

A note to drivers on our roads

    • Check your car tires treads and pressure before hitting rain slick roads
    • Know that middays can be the most dangerous
    • Plan ahead, check road conditions and give yourself plenty of time
    • Turn on your headlights
    • Slow down!
    • If you do end up skidding, don't panic
    • Don't drive through standing water
    • Pay attention, duh

    We have more detailed guidance: Your Guide To Driving Safely In The Rain In LA (And Really Anywhere).

    Worried about your heating bills?

    While the price of natural gas has come down from the sky-high levels that had many of us shocked at our gas bills, staying warm on a budget is still a concern.

    • State law requires residential units to have heating systems that can keep indoor temperatures at a minimum of 70 degrees. That means every dwelling unit and guest room offered for rent or lease should offer heating equipment, usually central air conditioning (A/C) or a wall heater. — Caitlin Hernández

    • Use heat smartly to save money: Cranking things like the A/C and wall heaters can be expensive. If money is tight, be judicious about how and when you use your utilities. For example, only use heaters at night or only set the thermostat to around 70 degrees.

    • Open and close those vents: If you have central A/C, look at where the vents are around your home. Are any open in places where you don’t stay long? Practice opening and closing those so warm air only goes where you need it (most vents should have a small toggle lever). Humidifiers can also help you warm things up — and it’s useful to add moisture into our dry air.

    • Adjust your wall heaters: If you have a wall heater, you can change the output by adjusting the knob (usually at the bottom). Since wall heaters can only warm the areas where they’re placed, it’s essential to close doors to rooms you won’t be in so hot air doesn’t get wasted.

    • Turn on your ceiling fan (really): If you have a ceiling fan, try turning it on. This sounds counterintuitive, but there’s science behind it. The direction a fan turns can push air in different directions, and since hot air floats up, you’ll want to move that around. Your fan should spin clockwise to create an updraft to circulate. Not all fans will have this option, though.

    Impact on the drought

    We're still in a drought. As our reporter Jacob Margolis noted during the first storms of the year, this is normal for our rainy season. Even if we see an average amount of precipitation, higher temperatures from climate change mean everything dries out faster — making drought conditions worse.

    Still, the rains have helped improve our drought situation. Here's the difference in conditions from January to now, according to the U.S. Drought Monitor:

    How we're reporting on this

    This story has been reported by Gillian Morán Pérez, with contributions from previous storm reporting. We will update this piece throughout the week.

    What Questions We're Asking

    • What damage are we anticipating?
    • When will the rains and wind come to an end?
    • What's the risk of mudslides?

    Your Questions Or Ideas

    What questions do you have about the weather we're experiencing?
    A massive winter storm is hitting Southern California. We're here to answer your questions.

    Corrected January 5, 2023 at 9:20 AM PST
    A previous version of this story used the wrong pronoun for meteorologist Ariel Cohen. LAist regrets the error.
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