Heat Wave Ahead For Midwest, East?

By Linda Lam
Published: August 18,2014



 
The Midwest and East have not experienced a heat wave yet this summer, but there may be a pattern change on the way for the second half of August. Our forecast guidance is indicating some more typical summertime heat will build into the Midwest and Ohio Valley at the end of this week as the jet stream pushes north into Canada.
(FORECAST: Chicago | St. Louis | Indianapolis | Cleveland)
An extended period of above-average temperatures are expected for much of the South. Dallas should top out in the upper 90s to near 100 degrees much of the week and Atlanta should see high temperatures in the mid 90s starting midweek. It will be humid as well, making it feel even hotter.
(FORECAST: Dallas | Atlanta | Memphis)
Forecast highs may flirt with daily record highs in the Deep South, particularly starting Thursday. Highs could push 100 in parts of middle and south Georgia and north Florida.
(HIGHS MAPS: Tue. | Wed. | Thu. | Fri. | Sat. | Sun.)
The Northeast will continue to get a break from summer-like temperatures this week. However, more oppressive heat and humidity may finally surge into the Northeast next week.
(FORECAST: Boston | New York | Pittsburgh)

Lack of Heat Waves

Daily record cool temperatures, both cool morning lows and cool afternoon highs, have been quite frequent this summer for much of the eastern half of the nation. Residents of Indiana and Arkansas saw their coolest July on record, and Illinois, Mississippi and Missouri saw their second coolest July.
Little Rock has only seen three days this summer with high temperatures at or above 95 degrees through Sunday. Their average is 16 days each year. The mean high temperature for the month of July was more than 5 degrees below average in Memphis and 2.5 degrees below average in Atlanta.
(MORE: Record Cool July)
Places like Pittsburgh, Indianapolis, Milwaukee, Grand Rapids and Buffalo still have yet to hit 90 degrees this year.
Chicago has seen only 3 days of 90 degree temperatures or higher and the average for a summer is 14. Minneapolis has only seen temperatures at 90 or above twice and the highest temperature recorded was 92 degrees on July 21.
The Midwest overall has not seen too many days with both excessively hot temperatures and high humidity.
The National Weather Service defines a heat wave as a period of abnormally and uncomfortably hot and unusually humid weather. Typically a heat wave lasts two or more days.
The definition for a heat wave from the American Meteorological Society's Glossary of Meteorology is a period of abnormally and uncomfortably hot and usually humid weather. To be considered a heat wave, such a period should last at least one day, but conventionally it lasts from several days to several weeks.
Why have we not seen any heat waves this summer? A dip in the jet stream has been over much of the East this summer, which has allowed cold fronts to push farther south than usual. This has brought the cooler and less humid conditions to the East.

The highest temperature Cleveland has seen this year was 90 degrees on June 17, 18 and 28. Detroit has also seen a shortage of hot days with only two days reaching above 90 degrees.
Temperatures have not been as cool, relative to average, in the Northeast as compared to the Midwest. However, we have not seen any heat waves for Boston or New York either.
A heat wave for much of the Northeast is generally defined as three or more days in a row with temperatures at or above 90 degrees.
Both cities have only climbed over the 90-degree mark four times this year. The first occurrence of a 90-degree day did not even happen until July 2 for both New York and Boston.