There's a reason we're complaining about the humidity.
This summer's incredibly muggy conditions have been at unusually high levels.
“Undoubtedly, yes, but how to quantify that is always a difficult thing to do,” said Harry Hillaker, climatologist for the State of Iowa.
There have been a couple of days this summer when the humidity was acutely uncomfortable. Monday evening was one of them.
Monday evening's dew point reached 79 in Omaha and 81 to 82 in southeast Nebraska, said Josh Boustead, meteorologist with the National Weather Service.
“That's about as high as we see in this part of the world,” Boustead said, typically occurring once or twice a summer.
“Wow, that would explain a lot,” said University of Nebraska Medical Center researcher Kaleb Michaud, who has begun analyzing the connection between weather and arthritis. “Even I felt that.”
Michaud noted that he was speaking in general terms, not specifically about his research, which has just begun.
“When it's that hot and humid, the body has trouble cooling down,” he said.
At suppertime Monday, the heat index in Omaha was 103, meaning it felt like 103 degrees when considering both the temperature and humidity.
At bedtime it still felt like 90 degrees, according to the National Weather Service.
High dew points
Dew points in Lincoln, the Omaha area and the Des Moines area have been significantly above normal.
So what is the dew point?
The dew point is the temperature at which the moisture in the atmosphere would condense into dew or fog. The closer together the dew point and temperature, the more saturated the air.
When temperature and dew points are the same, you have 100 percent humidity and it's likely raining or snowing, or fog is forming.
On the Nebraska side, this summer has seen the highest dew points in the Omaha and Lincoln areas in at least 15 years, said Natalie Umphlett, regional climatologist with the High Plains Regional Climate Center.
That's based on a review of 1996-2010 data from Lincoln and Mead, with Mead being a proxy for the Omaha area.
This summer, June and July averaged a dew point of 67.3 in each of those communities, she said. Last summer, the dew point averaged 62.4 at Mead and 62.9 in Lincoln.
“This is probably one of the most humid summers we've had,” she said.
In Des Moines, July's average dew point was 68 degrees, or 5 degrees above normal, Hillaker said.
“Five degrees may not sound like a lot, but that's a pretty big difference,” Hillaker said.
In mid-July, Des Moines had a heat index of 114, the highest Hillaker had heard of for the Iowa capital.
Earlier this summer, Omaha set and then matched the record for “precipitable water,'' a measure of the amount of moisture in the troposphere, the layer of atmosphere in which most weather occurs.
Boustead said precipitable water is a statistic of meteorological interest, helpful in forecasting rainfall, but it doesn't correlate to human comfort.
Plenty to blame
Just about everything is conspiring against us this summer.
Record to near-record local rainfall this summer has created a self-sustaining engine of humidity, because the water is cycling through the environment and back into the clouds.
Most wet summers are cooler than normal, but this summer has been atypically warmer than normal, Hillaker said. The heat and rain combined are a guaranteed recipe for unusually humid weather, he said.
Because it's hot and wet, plants, which love humidity, are growing more rapidly and pumping more moisture back into the air, Hillaker said.
During a hot, dry summer, those plants would grow more slowly and retain more moisture for growth.
“When you get into this cycle, it's hard to break out of it,” Hillaker said.
Relief around the corner
The arrival of August typically signals a shift in weather patterns, Hillaker said. Drier air from the north should begin supplanting some of that moist air from the Gulf of Mexico.
Still, this weekend the Midlands could see some of the summer's highest temperatures. Dave Fobert, meterologist for the National Weather Service, said highs in Omaha are forecast to reach the mid-90s.
The “good news” is that the warm air coming shouldn't be as humid as what the region has seen lately.
“It will still feel bad, but I don't know if it will feel as muggy,” he said.
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