From One Extreme to Another: A New Heat Dome Is Targeting the Western U.S.

While the eastern U.S. is the place sizzling this week, it will be the western part of the nation that is under the gun for rising temperatures next week. Here is a look at the upcoming heat pattern flip and what it means for wildfire danger in the West.

East to Cool Off While Temperatures Soar in the West

A dangerous heat wave continues to grip the East heading into the Fourth of July weekend. The extreme heat is forecast to persist well into the weekend before finally beginning to ease in the early part of next week, bringing temperatures back to more seasonable levels for the first half of July.

The massive heat dome that set up shop over the central U.S. earlier this week is expanding to the east as the holiday approaches. The latest forecast models suggest that the large zone of high pressure will begin to shrink over the southeastern corner of the U.S. this week, resulting in a breakdown of the heat dome to the north.

The easing of the heat dome this week will naturally translate to an uptick in thunderstorm activity across the Midwest and the Northeast over the next several days. The prevalence of storms will increase further by the beginning of the week in the eastern half of the country. Although these storms will not deliver immense moisture, any bit of rain will help after the long dry period.

Just as the temperatures are starting to come down in the central and eastern states, the mercury will begin to inch up in the western third of the country. Forecasters are predicting that a new heat dome will take shape in an area between the Pacific coastline and the Rockies.

A northward bulge in the jet stream over the West will bring up warmer air from the south, fueling the formation of this latest heat dome. How warm will it get? The models are signaling that temperatures will hit 10 to 20 degrees over the historical average for the second week of July for much of the western U.S.

The Southwest will bear the brunt of the heat with this weather event. Cities such as Las Vegas, Palm Springs, and Phoenix are expected to see the highest temperatures of the season thus far, even toastier than the record-breaking spring heat wave a few months ago.

The interior portions of the West will also sizzle as the heat dome expands. Temperatures in Denver will hover in the low to mid 90s throughout the week. There is a chance that mercury could eclipse the century mark in the Mile High City by the weekend.

It will be equally hot in Salt Lake City next week. You can expect highs to bounce around in the mid to upper 90s for several days. The following week is expected to see readings in the low 100s by the next week.

Elevated Wildfire Threat in the West Persists Under Emerging Heat Dome

In addition to the dangers brought on by the extreme heat, the temperature inversion that forms beneath the heat dome will generate light winds capable of trapping the existing wildfire smoke over the interior West. Air quality levels could suffer as a result of this pattern. Those with underlying health conditions that make them susceptible to smoky conditions will want to pay close attention to the air quality index in the days ahead.

The forecast of lighter winds is good news for the fire crews who have been battling the rash of wildfires across the western U.S. However, the increasing temperatures and dry conditions will support the development of new fires.

Utah has been the hot zone for wildfire activity so far this year. Fires have burned over 400,000 acres in the West over the last week. More than 70% of fires this season have sprung up in Utah.

There could be relief on the horizon for the parched region. The annual North American monsoon season is forecast to ignite toward the middle of July. The traditional shift of the wind patterns from the west to the south typically allows more humid air to come up from the Pacific and into the West, laying the groundwork for more rain showers and thunderstorm activity.

The beginning of the North American monsoon season is generally marked by sparse amounts of moisture and an increase in dry thunderstorms. These dry thunderstorms are known for their frequent lightning strikes that can start new fires in areas that have not seen much rain.

However, the monsoonal rains typically bring in more moisture as the season progresses. Until that time, the western U.S. needs to prepare for abnormally dry conditions and an elevated threat of wildfires. We will continue to keep tabs on the onset of the North American monsoon season, as well as where the greatest threat of wildfires will set up as the summer progresses. Stay tuned for all of the latest information as summer settles in across the West.

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