Heat Wave Relief Ahead For Midwest, Continues in South

By Linda Lam
Published: August 26, 2014

Parts of the Midwest and East had not experienced a heat wave yet this summer, but a pattern change has occurred, bringing searing 90s and some triple-digit heat for some. 

Fortunately, there is relief ahead for some, but not all. 

Midwest Relief

A cold front will glide through the Great Lakes before stalling out east-to-west by mid-week. 

This means some will see significant heat relief, while others will only see the top taken off the heat, not to mention the threat of thunderstorm clusters with locally heavy rain, hail and strong wind gusts.

(MORE: Severe Weather Forecast)

Tuesday's heat relief will cool off parts of the Upper Midwest, with 70s for highs in parts of Iowa, Wisconsin and southern Minnesota. Parts of the northern Great Lakes and northern Plains will see highs hold in the 60s.

Wednesday, cooler 70s or low 80s will spread east across the Great Lakes.

In the Northeast, a relatively benign warm-up by August standards through mid-week, generally into the upper 80s or low 90s, will give way to cooler temperatures later in the week.

(FORECAST: New York | Washington, D.C.)

Little Relief

Unfortunately, parts of the central Plains, southern Plains, mid-Mississippi Valley and Ohio Valley will remain sweating the details for the next couple of days.

Heat advisories and excessive heat warnings continue over a swath of the mid-Mississippi Valley, where highs will shoot well into the 90s the next several days. 

(FORECAST: St. Louis | Memphis)

More typical late August heat, but less hot than we've seen recently, will set in later this week from the southern Plains to the mid-Mississippi Valley, with highs in the upper 80s or 90s. The Tennessee Valley and Southeast will heat up as the week rolls on with highs generally in the 90s by mid-late week.

(FORECAST: Dallas | Atlanta)

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 six days this summer with high temperatures at or above 95 degrees through Monday. Their average is 30 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, Milwaukee, Grand Rapids and Buffalo still have yet to hit 90 degrees this year.

Indianapolis finally saw their first 90-degree high of the year Monday. Only 1960 (Sep. 1) had a later season's first 90+ high, there, while in 2004, not a single 90+ high was recorded.

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. 

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