Earth Matters Why late summer was exceptionally wet and humid
For the past three years, Connecticut has had parched summers. There might be white Christmases, mud-road Marches and April showers, but by the vernal solstice, the days got dry and the groundwater, scarce.
Enter 2018. From mid-July through the third week of August, it was as tropical as the Turks and Caicos here — the temperatures intemperate, the humidity jellified, and the rain a more-than-sometime thing.
And while heat-averse humans might curse — quietly as to not work up a sweat — the full wells and reservoirs rejoice.
For example, the Greater Bridgeport water system, which includes the Saugatuck Reservoir in Redding and Weston, is more than 99 percent full, said Peter Fazekas, director of public relations for Aquarion Water Co., which provides water to much of Fairfield County.
The Greenwich reservoir, Fazekas said, is 91 percent full; the Stamford reservoir, 94.6 percent full.
“It is definitely an improvement,” he said of this year compared to the previous three.
John Mullaney, a hydrologist with the US Geological Survey’s Water Science Center in East Hartford, which monitors stream flows and ground water levels throughout the state, said that unlike past years, when small streams and even some rivers ran dry, things are blessedly average this year.
“Our stream flows are all pretty much where they should be for this time of year,” he said.
What’s even more surprising, Mullaney said, is that in May and June, it looked like another drought year was about to parch us again.
“Then we really turned the corner,” he said.
What happened was that the jet stream arched north, allowing a Bermuda high — a flow of hot humid air northward — to settle over southern New England.
As a result, in was consistently hot.
Bill Jacquemin, senior meteorologist for the Connecticut Weather Center in Danbury, said the temperatures for June, July and August in Danbury were all higher than normal by three or four degrees.
The excessive humidity made things worse.
Gary Lessor, director of The Weather Center at Western Connecticut State University in Danbury, said most weather stations don’t track humidity.
“But I’ve heard it said it hasn’t been this humid since the early 1970s and I don’t think anyone will disagree,” Lessor said.
This saturated air created the perfect condition for thunderstorms.
Jacquemin said that normally a cold front will push through the state from the north or west to dislodge a Bermuda high after a few days. This year, he said, there were a lot of cold fronts, but none strong enough to knock the high pressure away for long. Instead, the mix of hot and cool air just made it rain a lot.
“It was like squeezing the water out of a sponge,” he said.
Matt Spies of Brookfield is the state coordinator for the CoCoRaHS program — Community Collaborative Rain, Hail & Snow Network. The 120 volunteers in the program make a daily check on their precipitation gauges, then send the data to a central location.
Spies said that normally the state gets about four inches of rain in August. CoCoRaHS volunteers measured about twice that throughout much of northern Fairfield and Litchfield County, from New Milford and Brookfield down to Ridgefield. One station in Newtown got almost 10 inches.
The increase in rainfall was even more dramatic from July 15 through Aug. 23 — the rainy season. Normally, Spies said, the state gets about five inches of rain in that 40-day period. This year, the volunteers were measuring rainfalls that were twice, or even three times that.
Jacquemin said Danbury got about 8. 3 inches of rain in August and about 18 inches for June, July and August — all well above average.
It’s the nature of thunderstorms that one place in town can get drenched while the next town over gets only a few fat drops. While the northwestern third of the state got drenched, Spies said, rain along the state’s coastline was normal.
“People in New London County were wondering why people were building arks up here,” he said.
There is a catch. Once the rain stopped falling on Aug. 23, it never started up again — until Thursday. It had been hot. Just not very wet. The water levels in the state’s rivers were beginning to drop again.
So that, if we have a really dry fall, all this summer’s rain may just mean everything averages out by year’s end.
“That’s what we get in New England,” Jacquemin said of the abrupt changes in weather patterns. “It’s like throwing a light switch.”
Contact Robert Miller at firstname.lastname@example.org