Heat waveDangerous Heat Wave Is Building in the Central and Eastern U.S.

Published 18 July 2019

The National Weather Service said Thursday that an upper-level ridge is building over the southeastern U.S., setting the stage for what will be a miserably hot and humid weekend for millions of Americans. Heat advisories and warnings affect 154 million Americans. In many major population centers, the heat index  is forecast to peak around 110 degrees between Friday and Sunday.

The National Weather Service said Thursday that an upper-level ridge is building over the southeastern U.S., setting the stage for what will be a miserably hot and humid weekend for millions of Americans. The sprawling area of high pressure will drive hot and humid air north and east from the Gulf through the Northeast.

Daytime temperatures will soar into and through the 90s from the Plains eastward, and overnight minimums in the 70s and 80s will provide little relief. The severe weather will be accompanied by an increasing threat of flash flooding in the Upper Midwest.

Heat Advisories, Excessive Heat Watches, and Excessive Heat Warnings are in effect for the Plains, Mississippi and Ohio Valleys, and the Eastern Seaboard.

The National Weather Service added that dozens of record high minimum temperatures will be set across the eastern U.S., and a handful of record high maximum temperatures will be challenged.

Heat advisories and warnings affect 154 million Americans. In many major population centers, the heat index — how hot it feels factoring in the humidity — is forecast to peak around 110 degrees between Friday and Sunday. The actual air temperature is expected to reach at least 95 for more than half the population of the Lower 48 over the next several days.

The heat wave is expected to persist through the weekend across the east, but a cold front ushering in cooler air will march across the U.S. as an upper-level trough begins to build near Hudson Bay.

Scattered thunderstorms are expected along fronts moving through the north-central U.S., a few of which could be severe and produce heavy rainfall. Slight Risks of both severe weather and excessive rainfall are in place this evening for parts of the Great Lakes region, with more storms possible across the Upper Midwest tomorrow.

Elsewhere, the trough responsible for the cooler temperatures and lower relative humidity in the Northwest will also raise concerns for fire weather conditions throughout the Intermountain West.

The Washington Post notes that as the climate warms because of human activities, numerous studies show that heat waves such as this one are becoming more common and intense, as well as longer-lasting.

An expansive study in the journal Proceedings of the National Academy of Sciences in 2017 found a climate change fingerprint in heat waves worldwide. Specifically, it showed that climate change has heightened the chances for record heat across more than 80 percent of the surface area of the globe that has sufficient weather data available. (This research excluded parts of the developing world, where weather monitoring networks are more sparse.)

In addition, a sweeping climate assessment published by the Trump administration last year found extreme heat events are on the increase in the United States and have been since the 1960s.

The Post offers the following city forecasts for several major cities:

·                  St. Louis: Hottest day? Friday. Forecast high? 98. Heat index? 109.

·                  Chicago: Hottest day? Friday. Forecast high? 96. Peak heat index? 102.

·                  Cincinnati: Hottest day? Friday. Forecast high? 96. Peak heat index? 107.

·                  Detroit: Hottest day? Saturday. Forecast high? 97. Peak heat index? 111.

·                  Washington: Hottest day? Saturday. Forecast high? 100. Peak heat index? 109.

·                  Philadelphia: Hottest day? Saturday. Forecast high: 99. Peak heat index? 110.

·                  New York: Hottest day? Saturday. Forecast high: 98. Peak heat index? 112.

·                  Boston? Hottest day? Saturday. Forecast high: 93. Peak heat index? 102.