When it comes to precipitation, California has already had an active start to the year.
Since the water year began on October 1, San Diego International Airport has received 8.82 inches of rain. This compares to an annual average of 9.79 inches. This means this part of the county is one inch away from reaching its average.
In San Diego, February is typically the wettest month of the year, according to NBC 7 Meteorologist Brooke Martell.
“We are used to accumulating about two and a quarter inches of rain during that period,” she said.
San Diego International Airport has already received about 4 inches of rain throughout February.
With the amount of rain we've received — not just this water year but even since last winter — we've done a good job with our drought monitor, Martell says.
“We only have about 7.2% of the state in abnormal drought conditions, not even drought conditions,” she said. These areas include North Redding, East Sacramento and Southeast Barstow.
According to the US Drought Monitor, less than 1% of California-Nevada remains in drought, compared to 100% a year ago. This means an improvement in drought by 5 degrees in areas such as the Central Valley. Recently, parts of southeastern California and neighboring Nevada and Utah saw drought removed/improved due to heavy rainfall caused by Hurricane Hillary and its remnants.
However, the big question remains: What about reservoir levels in California?
Reservoirs throughout the region are at or above historical averages through water year 2024.
Lake Shasta, one of the largest reservoirs in the state, is currently at about 83% capacity, about 123% of its historical average, Martell explained. Lake Don Pedro has a similar capacity, and other reservoirs around California aren't doing badly either.
What is an atmospheric river?
NBC 7 Meteorologist Greg Bledsoe explains what an atmospheric river is and how it affects our weather.
The term atmospheric river is defined as narrow regions in the atmosphere that transport large amounts of moisture to regions outside the tropics. It's like a river in the sky, Martell said.
While atmospheric rivers can vary greatly in size and strength, the average atmospheric river carries an amount of water vapor roughly equivalent to the average water flow at the mouth of the Mississippi River, according to the National Oceanic Atmospheric Administration (NOAA). When atmospheric rivers reach land, they often release water vapor in the form of rain or snow.
One particular atmospheric river you may have heard of on the West Coast is sometimes referred to as the Pineapple Express. The jet stream in the sky transports moist air from the Hawaiian Islands towards California. Because the stream is filled with moisture, it can bring heavy rain to California and heavy snow to the Sierra Nevada in the winter months.
On the West Coast, especially in California, most incoming precipitation is associated with atmospheric rivers, falling during only a few storms per year, said Dr. Anna Wilson of the Center for Western Weather and Extreme Waters at Scripps Institution of Oceanography. NBC 7 via email.
About 30-50% of annual precipitation in West Coast states accumulates with a few weather river events, NOAA said.
Like the National Oceanic and Atmospheric Administration, Wilson said atmospheric rivers can provide 50% more than California's water supply and can cause most of the flood-related damage — up to 84% in the 11 western states and up to 99% on the coast.
