USA — Firefighters on Wednesday were keeping a watchful eye on Arizona and New Mexico, as the triple threat of high heat, low humidity, and strong winds elevated the fire danger to extreme levels, according to the Storm Prediction Center in Norman, Okla. Already this spring, several large fires have charred the southwestern landscape, and an expanding drought suggests that this summer is going to be a busy one for the nations 2,000 elite hotshot crew members who are specially trained to fight Mother Natures most fearsome blazes.
Currently, large fires are burning in Arizona, New Mexico, and Colorado. The Gladiator Fire, near Crown King, Ariz., has already burned more than 15,000 acres, and was just 26 percent contained as of Wednesday.
While the Southwest fire season has gotten off to an early start, the total number of fires and acreage burned nationally to date is running below average, according to statistics from the National Interagency Fire Center (NIFC). Summer climate outlooks from the federal government and a private weather forecasting firm both suggest that the Rocky Mountains and Southwest are going to have a warmer summer than average.
The Climate Prediction Center (CPC), which is part of the National Oceanic and Atmospheric Administration (NOAA), is forecasting that a huge swath of the Lower 48 states, from northern California eastward to southern New Jersey, are likely to be warmer than average this summer. The region most likely to see warmer-than-average weather is the Southwest, where summer temperatures have exceeded the 30-year norm for about the past decade, according to Jon Gottschalk, CPCs head of forecasting operations.
Gottschalk said that in addition to recent trends, there is also overwhelming support for a warmer-than-average forecast across the Southwest based on computer model projections as well.
As the start of summer rapidly approaches, drought conditions have already been expanding throughout much of the West, and unusually warm conditions mean that the drought is likely to intensify.
The drought and warmer-than-normal weather are essentially two crucial ingredients in the making of fire danger, said Greg Carbin, a warning coordination meteorologist with NOAA’s Storm Prediction Center in Norman in an email interview. . . . We already have some of the ingredients in place, especially across the West, that give us reason to be concerned about an increasing fire weather danger in the months ahead.
According to NIFC, a federal center that coordinates wildland firefighting efforts, there is an above-normal potential for significant wildland fires this summer in much of Arizona and New Mexico, prior to the arrival of seasonal monsoon rains, which typically begin during July. The monsoon, which is characterized by daily rounds of showers and thunderstorms, also brings with it the threat of lightning strikes, which can ignite forest fires.
In fact, although human activities are the No. 1 cause of forest fires, lightning strikes are responsible for burning more acres, since they often ignite fires in areas that are harder for firefighters to reach, according to Ken Frederick, an NIFC spokesman.
In addition, potential hot spots this summer include Colorado, southern Montana, the mountains of Utah, California, Idaho, and Nevada. The Big Island of Hawaii also has an above-normal risk of significant wildfires, according to NIFC.
The fire danger across large parts of southern and central California, along with forests throughout the Sierra Nevada, is likely to increase later this summer, according to NIFCs outlook. As Climate Central reported on May 11, an above-average year for wildfires in California would come on the heels of a few years of relative quiet, compared to two devastatingly dry years in 2007 and 2008, when more than 800,000 acres burned.
Climate studies have shown that warmer winters, reduced snowpack, earlier snowmelts, and hotter, drier summers will likely lead to more California wildfires in coming decades. Other studies have shown similar jumps in wildfire activity may occur in parts of the Rocky Mountains as the climate continues to warm, largely in response to manmade greenhouse gas emissions. From La Niña to El Niño?
The current drought conditions are partly a legacy of back-to-back La Niña events in the tropical Pacific Ocean. La Niña events are characterized by cooler-than-average water temperatures in the eastern tropical Pacific, which can have a major influence on weather patterns worldwide. During the winter of 2011-12, La Niña favored a dry weather pattern across the southern states, as well as reduced mountain snowpack in much of the West.
The Southwestern U.S. got through the winter of 2011-2012 without a lot of precipitation because of the La Niña weather pattern, Frederick said. He said that drought conditions dont necessarily mean there will be more wildfires, but it increases the probability.
La Niña conditions ended in April, but there are some signs that an El Niño event, which is the opposite of La Nina and features unusually warm conditions in the Pacific, may develop later this summer. Such a scenario would alter the late summer fire outlook for some parts of the West.
If the U.S. does have a scorching summer, it would be consistent with recent trends. Last summer was the second-hottest on record, and the winter was the fourth-warmest.
The Lower 48 states just recorded its warmest 12-month period on record, which came on the heels of the hottest March and third warmest April on record. In addition, the January to April period was the warmest since record keeping began in 1895.
Notably, the top 10 warmest 12-month periods in the Lower 48 states have all occurred since 1999.
The national significant wildfire outlook for the summer, issued by the Interagency Fire Center. Click on image for a larger version. Credit: NIFC