Heat wave ends, expect cooler second half of July

COLUMBUS, Ohio (WCMH) -- Predictions for a hot, muggy summer materialized across much of the nation, boosted by a large "heat dome" extending from the Southwest to the Mid-Atlantic states in June

May was quite warm in Columbus (4.8 degrees above normal), followed by heat waves in mid-June and mid-July. Temperatures soared to 90 degrees or higher June 16-22 and July 12-16. The June heat wave was the longest so early in the season 1994 (June 13-22).

The maximum temperature reached the 90-degree mark on 8 days each in June and July so far. The hottest day was June 21 (96 degrees), the warmest weather the city has experienced in June since June 28, 2012 (100 degrees), the day before the derecho hit.

The upper-level pattern this summer has been anchored by high pressure systems in the mid-levels, with subsiding air that warms by compression in the Southwest and off the Southeast Coast, known as the traditional "Bermuda high."

The average temperature in Columbus since June 1 is running 2.3 degrees above normal, boosted by morning minimums in the low 70s, due to the high humidity.

The warmest morning brought a low temperature of 76 degrees on June 19, which set a daily record, followed by a low of 75 degrees on July 16. Record high minimums were observed on June 21-22 (73 degrees).

Where the jet stream buckles across the Upper Midwest and Northeast, thunderstorm complexes have barreled eastward producing damaging winds, hail and tornadoes. However, summer rainfall is often hit and miss farther south.

Persistent dryness has become a concern for some crops in the area, with a moderate drought reported across portions of central and eastern Ohio, bordering on severe drought in Pickaway County and east-central sections, based on the latest data from the U.S. Department of Agriculture (USDA).

Unfortunately, little in the way of rain is expected to ease the drought, as locations near and south of Interstate 70 are running only 35 to 70 percent of normal rainfall values since mid-June.

Long-range indications favor a seasonable second half of July, with a dip, or trough, in the jet stream that will feed somewhat cooler and drier air into the Midwest eastward to the scorched East Coast.

Even though more pleasant conditions will prevail for much of the remainder of the month, hot summers tend to be resilient, and another heat wave is certainly possible in August and early September.