Storms End Drought in Much of Northern California

According to the Drought Monitor analysis released Thursday, all of northern California north of Interstate 80 is now free of drought. 

If this active storm pattern continues through the next couple of months, substantial drought relief is possible. But it will likely take multiple near to above-average wet seasons to completely replenish reservoirs and ground water and to end the state's multi-year drought.

(MORE: California Rain, Snow Forecast)

One positive sign is that precipitation in the northern Sierra is on a record pace. More specifically, the eight stations in the northern Sierra used to gage precipitation in the region have seen the most precipitation on record since the start of the water year on Oct. 1 and are 218 percent of average for Jan. 11.   

Here's how much conditions have improved with the recent snow and rain.

How Much Drought Improvement?

As expected, drought conditions improved substantially over the last week in California.

Northern California has seen drought conditions improve since the beginning of October and drought has finally been erased for much of northern California as of Jan. 10, 2017. This is the first time since Dec. 20, 2011 that all areas north of Interstate 80 in California are completely out of drought.

In addition, much of central California and portions of southern California saw drought conditions recover by one drought category

Last year in early January, 44.84 percent of California was in the exceptional drought category, the highest on the scale from the U.S. Drought Monitor. As of Jan. 10, 2.13 percent remains in exceptional drought. 

The amount of California in drought conditions last January was 97.33 percent compared to 58.22 percent currently, which is an impressive change, especially in northern areas of the state.

When looking at this week compared to last week the change is quite remarkable. As of Jan. 3, 2017 just under 82 percent of California was experiencing at least abnormally dry conditions compared to just 65 percent as of Jan. 10. Last week 18.31 percent of the state was in the highest category, exceptional drought, and now only 2.13 percent remains in this category.

Since the water year began on Oct. 1, downtown Los Angeles has received 7.67 inches of rain, 2.51 inches above average through Wednesday and double compared to this time last year, when only 3.75 inches had fallen. 

Many other locations are also above average for the water season. Bakersfield has measured 3.96 inches since Oct. 1, 1.59 inches above average, and Fresno has picked up 7.57 inches, 3.31 inches greater than normal.

Prolific Snow

Abundant snow this season in the Sierra Nevada mountain range helped boost the snowpack in California. 

Last week, Winter Storm Helena brought heavy snow to parts of the West, including the Sierra Nevada mountains, where 56 inches was reported at Boreal and Soda Springs.

This round of snow was followed by Winter Storm Iras, a stronger and warmer system over the weekend into early this week. Because of the warmer temperatures, snow levels rose and snow melted at lower elevations.

Another system, Winter Storm Jupiter, arrived midweek bringing heavy snow and strong winds. Almost 80 inches of snow fell from Monday morning to Wednesday morning at Soda Springs and Kingvale. 

The National Weather Service in Reno said that this was the biggest snowstorm to hit the Sierra in six years.

(MORE: Where Snow This Season Has Already Topped 200 Inches)

However, as of Monday, the snow water equivalent is above average in the Sierra. Snow water equivalent refers to the amount of water contained in the snowpack.

The map above indicates how much above or below normal the snow water equivalent is for Jan. 12. Much of the West is experiencing near to above-average snow water equivalent.

Some areas are well above average, including California, Nevada and parts of Utah, where numerous areas are at 150 percent of average or higher.

According to the California Cooperative Snow Surveys, all regions are above average in terms of snow water equivalent, ranging from 131 percent to average in the north to 187 percent in the south, as of Jan. 11.

The snowpack is important because California receives most of its precipitation in the winter. Snow in the higher elevations will slowly melt as temperatures warm, providing water during the summer.

The snow so far this season is a good sign and it's possible the trend of above-average snowfall will continue.

Improving Reservoir Levels

The onslaught of heavy rainfall from this atmospheric river will help alleviate the drought in California, although as the past few days have shown, it can also be too much of a good thing.

Through Tuesday morning, 7-day rainfall totals were over 2 feet in a few spots, including at Three Peaks in southern Monterey County, where 26.45 inches was reported, and at Nature Point, just south of Yosemite National Park, where 24.99 inches was measured.

(MORE: Why Atmospheric Rivers Are a Blessing and a Curse)

This rainfall has helped lake and reservoir levels to rise. The second largest reservoir in California, Lake Oroville, in the northern part of the state, had an incredible increase from 789.40 feet Saturday to 805.52 feet Sunday and then up to 820.67 feet Monday, an astonishing rise of 31.27 feet in two days. As of Wednesday the lake had risen to 844.75 feet, which is more than 100 feet higher than a month ago.

Numerous reservoirs are now seeing levels greater than average, according to California's Department of Water Resources. Among them are:

• Success Lake is at 284 percent to average through Jan. 11
• Truckee River at Donner Lake is 266 percent to average through Jan. 11
• Hensley Lake is at 189 percent to average through Jan. 11
• The American River at Union Valley is 169 percent to average through Jan. 11
• Lake Sonoma is at 148 percent to average through Jan. 11
• Millerton Lake is at 144 percent to average through Jan. 11
• Lake McClure is at 139 percent to average through Jan. 11
• Don Pedro Reservoir is at 132 percent to average through Jan. 11
• Lake Shasta is 129 percent to average through Jan. 11

Lake Tahoe, which was at a level of 6223.3 feet on Jan. 1 and as of Jan. 10 is at 6224.3 feet, rose a foot in 10 days. It is also close to full pool, 6225.0 feet. 

MORE ON WEATHER.COM: Flooding in California and Nevada