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Western heat dome: Record highs, 50M alerts, Death Valley 126°F

An unusually strong heat dome is baking the western US, bringing the hottest temperatures of the year to tens of millions from California to Canada. Record highs are expected in at least 12 states, and nearly 50 million people are under heat alerts. This event caps a scorching July that may end up the warmest month on record across the US.

Western heat dome: Record highs, 50M alerts, Death Valley 126°F

Western heat dome: Record highs, 50M alerts, Death Valley 126°F

The short answer

A heat dome is a high-pressure system that acts like a lid on a pot, trapping hot air and intensifying temperatures. The current heat dome is unusually strong and high-reaching, allowing it to trap even more air and drive temperatures 10 to nearly 20 degrees above normal. CNN reports that nearly 50 million people are under heat alerts, with 12 million under 'extreme' Level 4 heat risk and 20 million under 'major' Level 3 risk. Death Valley is forecast to hit a blistering 126°F. The heat wave is part of a spate of record-breaking heat events affecting the US and Europe simultaneously, and climate change is making such extremes more likely, intense, and long-lasting, according to studies cited by CNN.

Why it's trending

The query 'wthr weather' appears to be a common misspelling of 'weather' that spiked as the heat dome intensified and forecasts showed record-breaking temperatures and widespread alerts. CNN's July 30 report triggered urgent interest as millions sought local forecasts and safety information ahead of a dangerous weekend.

An unusually strong heat dome is scorching much of the western United States this weekend, with CNN reporting that tens of millions of people from California to Canada will see the hottest temperatures so far this year. Dozens of record highs are expected to fall in at least 12 states, and nearly 50 million people are under heat alerts through the weekend.

The Washington Post adds that the scorching July may end up the warmest month on record across the US, while AP News highlights the accompanying heightened wildfire risk in parts of the West. Together, the sources paint a picture of a region already stressed by heat and seeing the potential for fire danger to escalate.

According to CNN, temperatures will climb 10 to nearly 20 degrees hotter than normal even for peak summer, from Southern California to the northern Rockies and Plains. The heat dome may set intensity records in parts of Southern California and Arizona. Death Valley is forecast to reach 126°F, which would be the hottest temperature of this heat wave.

This is the latest in a spate of record-breaking heat waves affecting the US and Europe simultaneously. CNN cites studies showing human-caused climate change is making heat waves more likely, more intense, and longer-lasting, though the link to more frequent strong heat domes remains an area of active research. Officials and forecasters urge residents to take the Level 4 'extreme' heat risk seriously, as anyone without access to cooling and hydration could be affected.

Timeline

  1. Heat dome develops over the West

    CNN reports an unusually strong heat dome is settling over the western US, bringing the hottest temperatures of the year to tens of millions. Nearly 50 million are placed under heat alerts, with dozens of record highs expected in 12 states.

  2. CNN issues forecast for record-challenging weekend

    CNN publishes a forecast showing Death Valley reaching 126°F and temperatures 10–20 degrees above normal. Nearly 12 million are under Level 4 'extreme' heat risk for Saturday and Sunday, with an additional 20 million under 'major' risk.

  3. July shaping to be warmest month on record

    The Washington Post reports that scorching July may end up the warmest month on record across the US, adding to the significance of the ongoing heat dome.

  4. AP News ties heat to wildfire risk

    AP News headlines report that the heat wave is bringing record-breaking temperatures and heightened wildfire risk to parts of the Western US.

Questions people ask

What is a heat dome?

A heat dome is a high-pressure system that acts like a lid on a pot, trapping hot air and preventing it from escaping. CNN explains that this particular dome is reaching higher into the atmosphere than typical, allowing it to trap even more air and raise surface temperatures further.

How hot will it get this weekend?

CNN forecasts temperatures 10 to nearly 20 degrees hotter than normal, with Death Valley expected to hit a blistering 126°F. Dozens of record highs are likely across at least 12 western states from California to Canada.

Is climate change responsible for this heat wave?

CNN reports that studies show human-caused climate change is making heat waves like this one more likely, more intense, and longer-lasting. However, the idea that particularly strong heat domes are becoming more common is an area of active research.

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Western heat dome: Record highs, 50M alerts, Death Valley 126°F | TakeTack