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NOAA logo, sun and text saying Heat Wave.July 19, 2007 — NOAA urges people in the Northern Plains and Midwest to prepare now for a heat wave expected to plague the region during the last 10 days of the month and possibly into August.

In the six to 10 day forecast issued on July 18, meteorologists at NOAA’s Climate Prediction Center called for an 80 percent chance for above-normal temperatures over North Dakota and northwestern Minnesota with odds greater than 50 percent for above-normal heat in a broad expanse of the nation extending from the Great Basin in the West to the Ohio Valley in the East. It is unusual for forecasters to show probability numbers that high in these forecasts. In addition, the Climate Prediction Center’s U.S. Hazards forecast released the same day warns of much above normal temperatures extending from Idaho to western New York during July 21-27.

“There is excellent agreement among forecast models on the development of a new heat wave, and this could surpass in duration, severity and impacts the heat waves we have already seen so far this summer,” said Douglas LeComte, meteorologist at NOAA’s Climate Prediction Center. The heat’s location and intensity make it a dangerous threat to people, crops and livestock.

Searing temperatures will come on the heels of unseasonably cool weather spreading over much of the Midwest and East from July 19-21. This relief from recent high temperatures will prove to be welcomed but brief, as a massive area of high pressure in the upper levels of the atmosphere, responsible for the sizzling heat in the West, migrates eastward. High temperatures will near the 90-degree mark once again in Minneapolis on July 22, and the Chicago area should begin to see the 90s by Tuesday.

Setting this heat apart from the earlier heat waves is that the high temperatures may linger longer and encompass a large chunk of the nation. The northern hemispheric circulation pattern is evolving into a very stable pattern, which will tend to keep the hot high pressure area nearly stationary over the continental U.S. into the end of July and probably into early August as well.

The week two temperature forecast, which goes to August 1, extends the area of 50 percent probabilities to the mid-Atlantic coast, suggesting that the expanding heat will visit the Boston-Washington corridor later in July. By July 26, thermometers could be topping out in the mid to high 90s from the Northern Plains to the East Coast. Much of the northern half of the country should see temperatures averaging at least five to 10 degrees Fahrenheit above normal during the last week of July.

"This outlook is significant in that early next week residents of North Dakota, Minnesota, Wisconsin and the upper Great Lakes will see temperatures and humidity levels common to Kansas City at this time of year," said Mike Looney, chief of services division at National Weather Service Central Region headquarters. "Temperatures 10-15 degrees above normal can pose a real danger to the elderly and the infirm, to children and to livestock and pets.  Once the high temperatures set in, it looks like they will persist for a while and the cumulative effect of extended exposure to heat brings additional problems."

NOAA’s National Weather Service has a variety of weather safety information available online. In particular, the publication Heat Wave: A Major Summer Killer. Know the symptoms of heat disorder to prevent heat-related illnesses and keep abreast of the latest weather forecast. Also, NOAA Weather Radio All Hazards is an excellent source for immediate broadcasts of severe weather warnings and civil emergency messages, giving those in harm’s way critical lead time to respond and remain safe.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

Relevant Web Sites
NOAA's Climate Prediction Center

NOAA’s National Weather Service

Heat Wave: A Major Summer Killer (PDF) and (Text)


Media Contact:
Carmeyia Gillis, NOAA Climate Prediction Center, (301) 763-8000 ext. 7163 or Patrick Slattery, NOAA Weather Service Central Region, (816) 268-3135