Borderland may be transitioning into a season of cooler weather and shorter days, but looking back on the summer months of 2012, meteorologists say they made their mark in the weather books.
Despite drought conditions earlier in the summer, and cooler temperatures later in the season, the summer ended warmer and wetter than normal according to the National Weather Service Duluth website.
“A couple of different factors contributed to the warmer, wetter weather,” explained Carol Christenson, warning coordination meteorologist for the NWS.
Christenson said the lack of cloud coverage during the summer played a big role in the warmer days.
“I don’t have specific details, but in retrospect, we didn’t have the cloudy days we typically get in the northland,” she said. “That sunshine really boosted overall temperatures.”
Combined, June, July and August ranked in as the 27th warmest on record, the NWS site said.
The average temperature for the summer season was 64.6 degrees, which is 1.5 degrees above the normal of 63.1 degrees.
“June and July are the months that contributed to the very warm summer with averages up 2 and almost 4 degrees, respectively, for each month,” Christenson told The Journal.
Wind direction also played a role in warmer days, she noted.
“Strong southwest winds are what we need to bring in warm air, and there were a lot of days where we had southernly winds,” Christenson said.
The summer ended with each month supporting at least one record-breaking day — but not all were for heat.
On June 25, a record low of 38 degrees was recorded to tie the old record set in 1996.
On July 13, a record rainfall amount of 2.85 inches was set to break the old record of 1.26 inches in 1921.
July ranked in at fourth place for the highest average maximum temperature for the month on record. The average maximum temperature was 82.9 degrees for the month.
In July, Dan Miller, science and operations officer for the NWS, attributed the warmer-than average month to a high-pressure ridge that settled in over a majority of the continental Midwest for a majority of the middle of June and most of July.
“This is the same ridge that has brought on a pretty severe drought and heat wave to other parts of the country,” he said. “The atmosphere has been very warm and that is why there is a ridge there. That bulk of low, sinking air has prevented upward motion which typically brings in the cloud coverage and precipitation.”
In addition, Miller said the longer days allow for temperatures to rise rapidly and stay warm into the late afternoon and evening hours. “When there is 14 hours of sunshine, there is of course going to be some warm temps.”
The cooler weather started its reign around Aug. 10 when record low temperatures were set one week apart on the 10th and again on Aug. 17.
The record-breaking days in August, kicked off Aug. 10, which recorded a low temperature of 38 degrees to break the old record of 39 degrees set last year.
One week later, on Aug. 17, a record low temperature of 41 degrees was set to tie the previous record set in 1958.
“August was on the cool side with about 1 degree below the normal,” Christenson said.
The meteorologist said the culprit for the cooler August temperatures was the clear skies and calm winds at night. “We got a very rapid cooling of lower atmosphere,” she said.
The crisp air that Borderland woke up to several times in August signals the frost season isn’t far away. Christenson said freezing temperatures make their way to the area by mid-September, with Sept. 7 being recorded as the average date for the first frost.
“It is almost a sure bet that by Sept. 20, International Falls will for sure have had its first freeze,” she said.
The high and low temperatures for June were: 88 degrees on June 9, 27 and 32 degrees on June 1; the high and lows for July were 90 degrees on July 20 and 45 degrees on July 27; and for August, the high was 89 degrees on Aug. 29 and the low was 37 degrees on Aug. 19.
A wet summer
Like thermometer readings, precipitation also bounced around during the summer months.
June kicked off with a short-lived trend of very dry weather, Christenson said.
“If we remember back to early summer, northern Minnesota was in a drought,” she noted. “We were experiencing conditions very much on the dry side. But, that changed with July storms.”
July swooped in to bring measurable precipitation 1.8 degrees above the area’s average.
“The reason July got so wet was the storms that hugged the Canadian border,” Christenson said. “They hit the International Falls area and then went back up into Canada. It left areas to the south very much on the dry side.”
July 13 brought in a 24-hour rainfall total of 2.85 inches, which gave the month more than half of its final amount.
Christenson said there were 10 days of measurable precipitation recorded in June; nine days in July, and five days in August.
She said that even though June had ond third of its days experiencing precipitation, the most that fell was .59 inches on June 10.
For a complete forecast, visit www.crh.noaa.gov/dlh or call 283-4615.
