The long-term forecast for summer? Depends on who you ask

Talk about it

For those planning summer outdoor activities the long-term forecast for June, July and August is now in. The temperatures for the rest of the summer will either be warmer or cooler than normal, depending on which forecast you believe.

“It is not going to be business as usual this summer,” said Ed O’Lenic, senior meteorologist for the National Oceanic and Atmospheric Administration. “It will be cooler than normal.”

O’Lenic credits high pressure areas in the northern latitudes for forcing stormy weather further south and bringing cooler temperatures to the Midwest.

“Just a couple of degrees cooler,” he said. “Just a 1- or 2-degree departure from normal.”

That would be a continuation of the weather patterns seen this spring when Jamestown recorded an average temperature of 52.5 degrees, about 4 degrees below normal, in May.

But other meteorologists believe in a slightly warmer forecast.

“Obviously, we are starting out cool but there is a significant pattern change on its way,” said John Wheeler, meteorologist for Forum Communications Co. “In a couple of weeks we could see temperatures closer to average or even above average.”

Wheeler credits the change to an adjustment in the jet stream that is in progress.

“Look for a much warmer second half of the summer,” he said. “We’ll see plenty of warm days where the air conditioning will run and people without A/C will wish they had it.”

Both forecast models are predicting normal precipitation patterns for the summer.

Temperatures play a part in the enjoyment of outdoor summer activities. They are also one of the major factors in yields of gardens and farm crops, and plants need more growing degree days to mature in time for harvest.

A growing degree day is defined as the difference between the average of the low and high temperature for the day and 50 degrees Fahrenheit. With a low of 40 degrees, for example, and a high of 80 degrees the average would be 60 degrees for the day or 10 GDD. It is also sometimes called a heat unit.

“A cool summer would hurt,” said Lance Brower, Stutsman County extension agent. “We need heat units for things to grow.”

According to the North Dakota State University Web site, the state averages between 1,900 GDD in the northern areas and 2,400 in the southeast. The Web site also said the state is already behind for 2009.

“Small grains like wheat, oats and barley, don’t require many heat units to mature,” Brower said. “That is why they are harvested earlier. Beans, corn and alfalfa all require a lot of heat units. They could come up short if we have a cool summer.”

It’s also not just farm crops affected by summer temperatures.

“Quite a few garden crops require heat units to get going,” Brower said. “If they’re not up by now you might want to consider planting something else.”

The normal average GDD for June 6 in North Dakota is 460 GDD. Actual as of that date was 376 for a shortage of 84 GDD or 18 percent of normal.

If temperatures do remain below normal all summer, it will be difficult for the GDD to reach normal levels.

An average temperature 1 degree below normal for a 100-day growing season would yield 100 less GDD or about a 5 percent reduction in the warmth needed for crops to mature.

“I hope we do get a warm-up,” Brower said. “You’ll see a lot of crop growth when the heat hits and the stalled crops warm up.”

Sun reporter Keith Norman can be reached at (701) 952-8452 or by e-mail at knorman@jamestownsun.com

Tags: local news, news, weather, temperature, jaestown, forecast, summer