Another Atmospheric River-Fueled Storm to Bring Widespread Rain in Southern California (2024)

Another storm arrived in to Southern California, bringing yet another round of rain to already soaked hillsides and raising the threat of flooding.

Southern California has been seeing consistent winter storms that have brought a significant amount of rain, snow and damage. The first three months of the year have already exceeded precipitation averages.

Atmospheric Rivers play a big part in the movement of moisture around the globe, and can make or break the rain season for California. When a strong atmospheric river points towards Southern California, we can see significant rainfall. Meteorologist David Biggar shows how common they are, and how they can impact our weather.

This next storm made its appearance Tuesday and will continue to deliver moderate to heavy rain Wednesday.

The rain will be light Tuesday morning and get heavier as the day moves into lunch time. The heaviest rain will come Tuesday night into early Wednesday morning.

By Wednesday afternoon the storm will move out of the region and leave a dry evening and rest of the week.

This will be a warm atmospheric river storm, meaning there will be much higher rainfall than typical winter storms.

The coast and valleys can expect about two to four inches of rain while the mountains and foothills will see about three to five inches.

"We can expect for our rivers to rise and a possibility of some street flooding," said NBC4 forecaster Belen De Leon.

Wind gusts will also be strong and may reach up to 60 mph in the desert and mountain areas.

Warnings and alerts issued

Officials across Southern California have issued weather-related warnings and alerts as the storm is expected to cause possible flooding.

The National Weather Service issued a flood watch for most of LA County that will go into effect at 2 p.m. Tuesday, this watch does not include the Antelope Valley. It will remain in effect until Wednesday morning.

The Santa Barbara County Sheriff's Office issued an evacuation order for communities in the Alisal and Cave Fire burn areas. The order takes effect at 8 a.m. Tuesday.

The Ventura County Sheriff's Department has also issued an evacuation warning for parts of the county that are areas of concerns. Ventura County saw severe flooding following the winter storms in January.

Some potential impacts from the storm:

• Travel delays due to flooded roads and mudslides/rockslides
• Shallow mud and debris flows
• Overflowing creeks, streams and river flooding
• Downed trees/power lines and power outages

Recent storms

Just a few weeks ago the mountain areas saw over seven feet of snow and hundreds of residents were trapped in their homes due to road closures and unsafe conditions.

Crews in the San Bernardino County mountain areas are still working to clear some of those roads but the continuous snowfall is making their job difficult.

LADWP worked around the clock to restore power to thousands of residents as the strong winds and rainfall caused downed powerlines.

The heavy rainfall also did a number on the roads causing potholes and sinkholes.

Communities in Northern California have sustained significant damage during the winter storms. In Monterey County, a levee break added to flood woes on the Central Coast.

What is an atmospheric river?

According to the National Oceanic and Atmospheric Administration, an atmospheric river is like a river that is flowing in the sky.

It transports most of its water vapor outside of the tropics. Atmospheric rivers are known to carry an amount of water vapor that is equivalent to an average flow of water from the Mississippi River.

When it releases its water and makes landfall it becomes snow or rain.

Atmospheric rivers are a big help for increasing overall water supply but are a significant contributor to flooding. They're also behind some of the most damaging storms in California history.

How is California's drought doing?

California saw a very wet January which allowed state water levels to rise followed by a dry February.

In just the first two weeks of March it appears to be a wet month with winter storms sweeping through.

According to the National Integrated Drought Information System, LA County along with Orange, Ventura and Riverside counties are currently at an abnormally dry state which is the lowest level on their U.S. Drought Monitor.

They also report that 2023 appears to be the "13th wettest year to date, over the past 129 years."

The NIDIS monitors droughts and responses of local, state and national levels across the country.

The rain and snow has helped many areas get out of a drought-like state but there are still parts that are dealing with Moderate and Severe Drought conditions.

According to the state's drought action site, the current March update shows that it will take more than a wet year for the state to fully recover from its record breaking drought that has lasted over the past three years.

The Sierra Nevada snowpack, California's natural water reservoir in the mountains, is well above normal for this time of year. Ideally, that snow gradually melts in the spring and summer as runoff and replenishes the state's water supply and storage system.

Rainfall averages

The National Weather Service Forecast Office has reported that the downtown LA area has already more than doubled its precipitation totals in one year.

Average precipitation for February in downtown LA is 3.64 inches. In February 2022, the area only recorded 0.06 inches, but in this year downtown LA saw 5.95 inches of precipitation in February.

The same can be said for the comparison of the months of January in one year. The average for the month of January is 3.29 inches and in 2022 we saw .19 inches and in 2023 we saw 8.95 inches.

March has already seen multiple storms and could also bring above-normal precipitation.