ADDISON COUNTY — According to National Weather Service meteorologist Kimberly McMahon, the data the agency collects at the Burlington International Airport show things started getting unusual in the middle of May.
In fact, temperatures for the first six months of year remain “right around normal,” McMahon said.
So, too, did precipitation amounts for the first four-and-a-half months of 2013. In fact, if anything, there was a little less snow and rain overall.
“Toward the middle of May, we were below normal,” McMahon said.
Since then, Vermont residents have not had to be meteorologists to describe the state’s weather.
Hoses and watering cans are gathering cobwebs in garden sheds.
Athletic directors had to postpone a Division I high school softball playoff game involving teams from opposite ends of the state — Missisquoi and Mount Anthony — a half-dozen times because of downpours or soggy fields.
It’s official: Mud season was moved from March and April to May and June.
McMahon and the National Weather Service (NWS), of course, have the facts to prove just how wet it was: May and June combined were the rainiest back-to-back months on record at the Burlington airport — a combined 18.6 inches.
May’s 8.74 inches set an NWS station record, beating out the May 2011 total of 8.67 inches.
June’s 9.86 inches at the airport stands second only to 1922’s 9.92 inches.
The combined 18.6 inches knocked 1998’s July-August total of 17.97 inches off its consecutive-month perch. Longtime residents of Addison County will remember the summer flood of 1998.
The average precipitation measured by the NWS for the first six months is 16.00. The 18.6 inches in May and June alone brings the midpoint 2013 total to 25.13 inches.
Sun was rare after early May, which saw a prolonged heat wave. Then, 14 days in May and 18 days in June saw measurable totals of rain (at least a hundredth of an inch), and 27 days in the two months saw at least a tenth of an inch, compared to an average of about 15 days.
A half-inch of rain or more fell on the airport on 13 days in May and June, compared to an average of fewer than five.
Results varied around the state. Less rain fell on two Addison County stations for which the NWS has data, Salisbury and South Lincoln, but McMahon noted results depended on where thunderstorms struck.
“That’s what happens with convection. All it takes is one thunderstorm … to make a huge difference,” McMahon said.
And even in Salisbury, with a smaller two-month total of 11.75 inches of rain, including about six inches in June, the sun often remained behind clouds: In June, at least a hundredth of an inch of rain fell on 20 of 30 days.
ATLANTIC HIGH PRESSURE
McMahon said an unusually strong high-pressure system stalled over the Atlantic Ocean is locking the region’s weather pattern in place, and in fact is backing up weather across the nation and contributing to the brutal Southwestern heat wave.
The Atlantic high is holding low pressure over the Northeast, she said, while Southern heat and moisture is drifting up and causing our repetitive weather pattern.
“There’s been high pressure out in the Atlantic,” McMahon said. “It’s pretty strong and has been blocking all movement upstream of it … There’s low pressure over us, and it’s allowing moisture from the South and warm air from the South to continue to feed up the coast.”
And there is nothing on the horizon that appears ready to dislodge the Atlantic high, meaning the region is most likely due for more of the same, at least in the short term.
“It (the high) would need to weaken, and part of what would help the high pressure to weaken would be a really strong low pressure system to make that high slowly erode,” McMahon said. “One thought is possibly a tropical system, a tropical storm or a hurricane would help … It looks like it would have to be a pretty significant low pressure system or storm to weaken that high pressure.”
On Monday, McMahon held out some hope for at least a couple nice days ahead.
“It looks like we will at least get a break this coming weekend,” McMahon said. “(The high pressure) should move a little to the northwest and give us a break … but then it’s going to sag south, and unfortunately there is a chance of more showers and thunderstorms toward the beginning of next week.”
And, she said, no weather pattern lasts forever, even if it takes a while for a new pattern to arrive.
“Eventually, there will be a regime change, or a change in where this high pressure is, but it is a real slow process,” McMahon said. “It does look like it will change eventually.”
Andy Kirkaldy may be reached at [email protected].