An Intense Heat Wave Will Blanket Much of the U.S. This Week


This would be a completely reasonable response to this week's weather. Image credit: STR/AFP/Getty Images

A dangerous heat wave is on track to envelop the eastern two-thirds of the United States this week, baking cities from the Plains to the Atlantic with temperatures that could rival the hottest summer days you can remember. While heat is nowhere near as thrilling to talk about as a raging hurricane or a massive tornado, on average, heat claims more lives each year than an entire year’s worth of tornadoes and hurricanes combined.

The extended period of very hot temperatures—which the media has settled on calling a “heat dome,” for reasons we’ll get into in a moment—will slowly build into place over the central United States this week before setting up shop on the East Coast this weekend, roasting the big cities along the Interstate 95 corridor with temperatures that could easily hit or exceed 100°F.

The heat will quickly crank up as the week drags on, with temperatures and heat indices approaching dangerous levels by the middle of the week. The Plains will see afternoon highs hovering around 100°F Tuesday through Friday, while folks who live in the southeastern and Midwestern United States will have to endure afternoon highs in the middle and upper 90s late this week and through the weekend.

The Weather Channel’s high temperature forecast for Saturday, July 23, 2016. Image credit: The Weather Channel

Major cities along the East Coast—including Atlanta, Charlotte, Raleigh, Washington, D.C., Baltimore, Philadelphia, and New York City—could see some of their hottest days in years. The National Weather Service currently expects high temperatures to fall just short of the century mark in most of these cities on Saturday and Sunday, but weather models have continuously hinted that highs could reach record levels this weekend. The Weather Channel’s forecast yesterday, July 18, called for triple-digit highs from Phoenix to Washington on Saturday, July 23.

It’s not only the heat that gets you—if you’ve ever been to the south in July, you know that the oppressive humidity makes the heat feel almost unbearable. The heat index is the temperature it feels like to your body when you factor together both heat and humidity. If the air temperature is 95°F but the heat index is 110°F, it means that the humidity makes your body work as hard as it would were the actual air temperature 110°F. Heat-related illnesses can quickly set in if you’re exposed to heat for too long, so taking frequent breaks and drinking lots of water is necessary to stay safe.

A weather model image showing the 500 millibar level of the atmosphere expected on Wednesday, July 20. The model shows the intense “dome” of heat stuck in the center of the country. Image credit: Pivotal Weather

This heat wave is commonly being referred to as a “heat dome” in weather forecasts due to the enormous ridge of high pressure that will cause all the headaches (and sweating). The jet stream will retreat to the Canadian border for the duration of the event, leaving an expansive high pressure to its south. Areas of high pressure are characterized by sinking air, which leads to dry and hot weather.

The heat dome is more commonly referred to as a “ring of fire” due to its shape on weather maps and the dangerous storms that tend to occur on the outer periphery of the ridge of high pressure. Folks who live near the edge of a heat wave often find themselves staring down the horizon at some powerful storms, as the temperature gradient, upper-level winds, and pools of moisture that collect along the outer edges of heat waves are prime environments for the development of damaging squall lines. Some strong thunderstorms are possible along the northern and eastern parts of the United States for the duration of the heat wave.

Remember that cities get hotter than their suburbs due to the urban heat island effect, and the phenomenon is even worse during a heat wave. The elderly, ill, or folks who can’t afford to cool down are especially vulnerable during a heat wave like this, as buildings don’t cool off at night when daytime temperatures run this high. Check on your vulnerable neighbors until things cool down, and take it easy if you have to spend time working or walking along city streets during the day.