As if the drought isn’t enough to worry about, weather officials say California is likely to experience a hotter-than-normal summer this year, a phenomenon certain to add anxiety for water agencies and fire departments.
Summer doesn’t officially begin until Saturday. But the heat already is scorching the record books, as seen by a wave of 100-degree weather that swept across Northern California early last week. Heat records fell at six locations in the Sacramento Valley, including downtown Sacramento, which saw a high of 107 degrees last Monday. That shattered the date’s record of 103, set in 1883.
This follows what already has been an unusually warm winter and spring. In a study released Thursday, the National Climatic Data Center reported that California experienced its warmest January through May on record, with temperatures 5 degrees above the 20th-century average. Five California cities also set records: Sacramento, Los Angeles, San Diego, San Francisco and Eureka. In Sacramento’s case, the first five months of this year were 3.7 degrees warmer than the average over the past 30 years.
In its long-range forecasts, the National Weather Service is reporting that odds favor a summer across all of California that is warmer than average. The agency extends that forecast all the way into October, the earliest that Californians normally expect seasonal rains to resume.
“We expect that this year, the factors that contribute to above-normal temperatures are slightly favored compared to normal,” said David Unger, a meteorologist who helps develop the forecast for the National Weather Service’s Climate Prediction Center in College Park, Md. “That just means the odds favor above normal, but it’s by no means a guarantee.”
The prediction is based on a variety of factors, including recent atmospheric temperature trends, Pacific Ocean water temperatures, and computer models that factor in historical climate patterns. It also considers soil moisture, of which there is very little this year. In effect, drought makes it more likely the summer will be hot.
“Some of the sun’s energy is taken up by evaporation,” Unger said. “So if the soil moisture is drier, that means more energy goes into heating and less goes into evaporating the water.”
That’s exactly what worries firefighting officials. Exceptionally low humidity and dry vegetation are a combination they don’t want.
“Statewide, we’re seeing extremely dry conditions just about everywhere,” said Cal Fire director Ken Pimlott. “Because the vegetation is absolutely so dry, it only takes one ignition under the right conditions for these fires to take off. One spark has the potential to be a wildfire.”
Extra heat and low humidity will also mean more demand for water, both on farms and in urban areas. Water officials worry it will be harder to get customers to comply with conservation demands as they watch plants scorch and wither.
“Increased heat tends to transfer to increased water demands, whether for crops or urban landscaping,” said Jeanine Jones, interstate resources manager at the California Department of Water Resources.
Already, many local water agencies across the state have had difficulty getting customers to meet water-conservation targets. They are increasing enforcement and public education activities as a result.
On Friday, the city of Sacramento launched an unusual “dawn patrol,” putting enforcement teams on the streets of certain neighborhoods before sunrise to catch early-morning watering scofflaws. It handed out 91 violation notices. The violators were easy to catch, because landscape watering is banned citywide on Fridays – as well as Mondays and Thursdays. Residents and business owners may water only two days a week based on address: Tuesday and Saturday for odd-numbered addresses, Wednesday and Sunday for even numbers.
The city estimates residents have cut their water use 16 percent compared to normal, which falls short of the 20 percent conservation order. Even so, that’s better than many other communities. The El Dorado Irrigation District has called for 30 percent conservation, but customers have achieved only 6 percent.
“Increased heat is an example of something that could be used to focus (public information) messaging to remember these are the requirements,” Jones said. “It’s difficult to get many people to change their irrigation controllers. A lot of people just kind of set it and forget it.”
Cal Fire is also stepping up its fire-prevention message, with radio and television advertising to start this week. As of June 7, Cal Fire had responded to 2,118 fires statewide so far this calendar year, said Janet Upton, a spokeswoman for the agency. That’s substantially more than the average of 1,255 fires over the past five years. Last year over the same period, there were 1,781 fires.
The first big warning sign came in January with an unusual fire in Humboldt County. The Red fire, as it was called, burned about 350 acres in mountains east of Eureka, normally one of the wettest places in America in January. Upton called the fire “very foreboding” because it hints at broader dangers for the rest of the state as hot weather continues to dry out anything that might be flammable.
“This is all very concerning to us, because it’s literally adding fuel to the fire,” she said. “The fire behavior itself is actually being driven by the extreme dryness.”
In response, Cal Fire hired 400 seasonal firefighters by the first week of February. They normally don’t get hired until July. It also hired 63 additional fire apparatus engineers to operate fire engines to create what Upton called “surge capacity,” or the ability to rapidly move masses of firefighters and equipment to respond to emergencies.
Cal Fire also just signed a contract for exclusive use of a DC-7 aircraft. This “heavy” tanker aircraft can carry 3,000 gallons of water or fire retardant and will augment Cal Fire’s existing fleet of more than 50 aircraft, which are all smaller. It will not be based at a particular location, but will travel in response to the greatest fire threat. The $5.4 million contract is with AeroAir of Hillsboro, Ore., and runs through October.
The U.S. Forest Service has recorded 299 fires on its land so far this year; those numbers are similar to last year but represent a big increase compared with the last normal rain year, 2011, which saw 113 fires.
Fire activity is expected to pick up because drought has caused the mountains to lose their snowpack much earlier than usual, and forests will begin drying rapidly.
“This lack of snowpack has resulted in vast expanses of vegetation being exposed to the weather elements much sooner and for longer than normal,” Forest Service spokesman John Heil said via email. “The current dry conditions across Northern California are more typical of fall and were unprecedented for the latter part of the wet season,”
A more alarming statistic is the growth in human-caused fires versus those caused by lightning. In 2010, just 18 percent of fires on Forest Service lands were cause by people or human activity. That has increased steadily every year since and stands at 88 percent so far this year.
That begins to rival data from Cal Fire, which sees more human-caused fires because it operates in urban and semi-rural areas. Cal Fire incidents are routinely about 95 percent caused by people, Upton said.
In extremely hot and dry conditions, Cal Fire has seen fires triggered by sparks from all manner of human activities, from the mundane to the reverential. Upton said fires have been started by sparks from a shod horse walking through gravel, a golf club striking a rock in the rough, and a shovel hitting a rock when a family was burying a beloved dog.
“We can’t stress enough that this year, more than ever, the public needs to be cognizant of their role in preventing fires,” she said. “They are a huge part of this equation in trying to keep the damage down this year.”
Call The Bee’s Matt Weiser at (916) 321-1264. Follow him on Twitter @matt_weiser.