Wind energy is butting up against the effects of sluggish weather in the West, where wind patterns have changed and renewable energy production is at a near five-year low.

The government's Energy Information Administration detailed the findings earlier this month in a study that showed falling wind energy production in California, Oregon and Washington state — typically known as a bastion for clean energy development.

The agency didn't say how the wind energy slump would affect the electric grid, but it did say it could hinder wind farms from taking advantage of a key federal tax subsidy and harm their economic viability. Clean energy companies rely on the subsidy to fund projects.

The changing weather patterns also could force states to tap other forms of energy, including fossil fuels, to make up for the lost wind capacity, according to the study.

The agency found that wind energy in the West fell to below-average levels in early 2015 and through the spring due to changing wind patterns. The weather change resulted in the lowest production cycle in the region for five years, even as wind turbine development has grown substantially.

Even small changes in wind speed can dramatically reduce electricity output from wind turbines, the Energy Information Administration said. "For instance, in January, wind speeds were approximately 20 percent to 45 percent lower than normal for some portions of the West Coast, but capacity factors for wind plants in California, Oregon and Washington were approximately 50 percent lower than the January average of the previous five years," the study reads.

The findings are even more startling when considering that the agency also forecasts electricity from hydropower dams falling dramatically due to the drought there. That could place greater reliance on wind to fill the renewable energy gap in the region, which historically has relied on hydro for its power supply. But given wind's lagging production, it is uncertain what will happen.

The agency, which is the Energy Department's independent statistics arm, does suggest that wind energy would face increasingly difficult economic hurdles if production remains low.

The study says a key federal tax subsidy for the wind industry, which is based on production, would shrink. The wind industry says the incentive, known as the Production Tax Credit, is a crucial part of making wind competitive with other forms of power generation.

"Wind plant generation variability occurs over different time scales, from subhourly to seasonally and even annually, reflecting variations in wind speeds," the study says. "Furthermore, because the federal tax credit for utility-scale wind energy is based on generation volumes, lower wind speeds mean reduced tax credits."

It also says that "unexpected drops in output may require grid operators to schedule other sources of power on short notice." Observers say that implies relying on more natural gas-fired plants to fill in the gaps in renewable electricity production.

The wind industry says these fluctuations in production should not be seen as a trend. The America Wind Energy Association says in a statement that the variability is consistent with normal wind turbine operations. “Even if [first quarter 2015] production levels were to persist proportionately throughout the year, they would be within” an expected average production range of 70 and 120 percent. “And, as averages work, we can expect above-average production in other quarters [as seen in 2014] to offset the below-average production in [early 2015]," according to the trade group.

Only California's wind turbines have returned to normal production since the spring, with states in the Northwest still suffering from below-average production, the agency says. "California wind turbine performance appears to have recovered to near-normal levels, but turbine performance in Oregon and Washington remains below average 2010-14 levels," the study reads.

The agency is quiet on the reasons for the shift in wind production. It doesn't talk about why it is occurring or the effects of global warming on wind energy. However, research conducted in the last five years by atmospheric scientist Diandong Ren, from the University of Texas at Austin, shows that shifting weather patterns from a warming climate will have substantial effects on wind energy production in certain regions.

Wind energy on the whole, however, will continue to grow with solar power, the Energy Information Administration said in a separate energy forecast issued this month. The Southeast is embracing more solar energy, which the agency attributes to companies trying to make good on a federal investment tax credit for solar, separate from the wind credit, that is currently scheduled to ratchet down at the end of 2016.

"According to current law, projects coming online after the end of 2016 will see a federal investment tax credit of 10 percent, below the 30 percent investment tax credit available for projects that come online before the end of 2016," the agency's latest forecast reads. "This impending decline in the tax credit provides a strong incentive for projects to enter service before the end of 2016."

But wind will outpace solar development by nearly twice the rate through 2016, the agency says.