Monday, January 27, 2014

[californiadisasters] Coast To Cactus California Drought Analysis

California has entered another drought. Let's start by looking at drought across the entire country, monitored by the U.S. Drought Monitor. The latest weekly update shows drought conditions in the western Great Plains and over much of the West. For the last year it's been getting worse in California and Nevada as shown by the Drought Monitor image (below). The drought of 2012 that impacted
so much of the central U.S. has eased, based on greater precipitation in the past year. The improving conditions are shown by the bluish colors on the
drought monitor change image at lower right. But drought conditions have inten-
sified in the far west as shown by the brown colors over California.

As we move through the middle of California's important wet season, the entire
state is running very dry. Outside of the northern Rockies and portions of Nevada and Utah, most of the West was very dry in December.
Areas along the coasts of California, Oregon and Washington had precipitation that was 9-12 inches below normal for the month. In fact, many cities in California and Oregon recorded their driest calendar year on record in 2013, including Los Angeles, Riverside, San Francisco, Sacramento, and Eugene, Oregon. Some of these records go back 150 years. Looking at the six most populated cities in California (chart below), San Diego is the only city that has received more than 50 percent of its normal yearly rainfall, yet San Diego is still well below their normal yearly rainfall total. One impressive (depressive?) example is Shasta Dam, where only 16.89 inches was reported in 2013, more than 11 inches below the previous record low of 27.99 inches in 1976. Shasta's calendar year aver-
age is 62.72 inches! Upper elevation Sierra station snowpack and snow water equivalent (SWE) values in California have been abysmal, running at 16 percent of normal for the water year (since October 1) as of January 10.

What's going on? Why isn't California getting any rain? A very persistent high pressure ridge has been locked in place along the west coast for much of the fall and winter. Pacific storms are deflected to the north and east by this strong ridge, typified by the pattern shown on the weather map at left. The few storms we've had in California have swept down from the north, from Canada, a relatively dry source region.

According to the National Drought Mitigation Center, there seems to be no relief in sight as the calendar flips over to 2014. California appeared to be headed for a third dry winter because storms had not materialized to deepen the snowpack in the Sierra Nevada. California State Water Project officials estimated in November that the initial water allocation would be just 5 percent of contracted amounts, given the past two years of below normal precipitation and low reservoir levels.

Livestock producers needed rain to get Central Valley pastures growing for winter grazing. Ranchers were selling some cattle, buying feed to get through the winter and wondering whether they would need to haul water.

California lawmakers since December had been urging Gov. Jerry Brown to declare a drought emergency for California. He finally did so on January 17.

Cal Fire suspended burn permits in central California, due to dry conditions and a high number of wildfires for this time of year. Burn permit holders could not conduct burns in numerous counties. Cal Fire was also staffing extra crews and keeping the summer engines used for fighting fires in rough terrain on hand.

What's the prognosis? Not so good. While there's still time for the overall long wave pattern over the Pacific to change and salvage a decent rainfall season in February and March, the stubborn dry ridge pattern shows no signs of abating.
The Climate Prediction Center (CPC) says the odds favor more dry weather February through April (see graphic lower left). The CPC's drought outlook for the same period reflects that thinking as well (lower right). And California's cli-
mate normally turns off the water tap during the Spring, so the clock is ticking.



Be sure to check out our Links Section at
Please join our Discussion Group at for topical but extended discussions started here or for less topical but nonetheless relevant messages.

Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe


No comments:

Post a Comment