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Heat dome brings record-breaking high temperatures to the West, exacerbating drought and wildfires

Much of the the western U.S. is enduring a punishing and unforgiving summer of heat, drought and wildfires.

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Much of the western USA is enduring a punishing and unforgiving summer of heat, drought and wildfires. Hundreds of heat records have been shattered, and drought encompasses a whopping 94% of the West. Wildfires have scorched nearly 4,000 square miles, an area larger than the states of Delaware and Rhode Island put together. 

This cauldron of misery has been exacerbated by a sprawling heat dome that's wandered around the West this summer, sending temperatures skyrocketing. A heat dome occurs when the atmosphere traps hot air like a lid or cap.

What is a heat dome?

A heat dome is the result of a strong change in ocean temperatures from west to east in the tropical Pacific Ocean during the preceding winter, according to the National Ocean Service. The warm air coming from the west part of the Pacific Ocean gets trapped in the jet stream as it approaches land.

When that hot air arrives over land, the atmosphere traps it. Winds can move the heat dome around; hence, it is also referred to as a heat wave.

Western states plagued by drought conditions

Nearly 60 million people in the West are enduring a drought, all the way from Washington to New Mexico. Nearly 95% of the region is in a drought, the highest percentage in at least the past 20 years, according to the U.S. Drought Monitor

"Extreme, record-breaking heat leading up to this week has resulted in rapid deteriorations in drought conditions across the Pacific Northwest, northern Great Basin and Northern Rockies," the Drought Monitor said. 

In Oregon, where drought has intensified and expanded from severe to exceptional levels, soil moisture, stream flow and the Standardized Precipitation Evapotranspiration Index (a drought-monitoring indicator that includes the effects of precipitation and temperature) show conditions are among the driest going back to 1895, the Drought Monitor said this month.

Montana recorded less than 25% of its normal precipitation in June, which is historically its highest precipitation month. Impacts there included infestations of grasshoppers. 

Excessive heat contributes to wildfires

The hot, dry air underneath the heat dome created tinderbox conditions conducive to the spread of wildfires, the Capital Weather Gang said. 

"A large dome of high pressure will continue to bring extreme heat across the northern Rockies and northern Plains into the middle of this week," AccuWeather meteorologist Robert Richards said Monday.

Along with the above-average temperatures, the combination of extreme drought, gusty winds and lightning from thunderstorms could make conditions ripe throughout the West for wildfires to form and spread uncontrollably this week, the National Weather Service said.

The heat dome can thrust temperatures 10 to 20 degrees above average. Some places in Montana, Idaho and North Dakota could reach triple digits this week, AccuWeather predicted.

Role of climate change in extreme heat

Extreme conditions like what the West is enduring this summer are often from a combination of unusual random, short-term and natural weather patterns heightened by long-term, human-caused climate change.

Scientists have long warned that the weather will get wilder as the world warms. Climate change has made the West much warmer and drier in the past 30 years. Special calculations will be needed to determine how much global warming is to blame, if at all, for a single extreme weather event such as this summer's extreme heat.

"With regard to climate change, it is expected that the jet stream will become more wavy in the future as average temperatures continue to climb, making these large deviations, and subsequently extreme heat events, more common," AccuWeather senior meteorologist Randy Adkins said.

Wildfire smoke reaches most of US

SOURCE NOAA; PHOTO image at top: GoogleEarth; Contributing John Bacon, USA TODAY; The Associated Press

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