Many Americans are reaching for their jackets less than a week after a sweltering heat wave pushed temperatures to record highs, as a cold front sweeps across the country that's expected to last up to two weeks.

The cooler weather, which will sink temperatures between 5 and 20 degrees lower than July averages, will primarily affect the Upper Midwest, causing thunderstorms from Michigan to Illinois to eastern Missouri on Friday.

Temperatures on Friday will average 75 degrees Fahrenheit in Chicago, 70 degrees in Boston and 86 degrees in Charlotte, N.C. Saturday looks to be a little cooler than Friday.

'The quick change of air mass to cool Canadian air is unusual in that the northwest flow is also going to last a week or two,' said Bill Karins, a meteorologist for NBC News. 'Typically a cool spell in the summer would last one or two days.'

The cool air comes as a relief after a week of excessive warmth that baked every region of the country with several days of record-breaking highs pushing the heat index above 100 degrees.

Last week should be the worst of the summer in terms of heat, according to Boston meteorologist David Epstein.

Saying that he believes the worst of the heat is over, Epstein explained that severe heatwaves aren't sustainable as the summer wears on due to a number of factors including less daylight and the sun being at a lower angle, 'the likelihood of a weeklong heat wave starts to diminish.'

Event Time
2013-07-26 07:07:17 UTC
2013-07-26 18:07:17 UTC+11:00 at epicenter

Location
15.362°S 167.584°E depth=135.5km (84.2mi)

Nearby Cities
48km (30mi) ENE of Luganville, Vanuatu
274km (170mi) NNW of Port-Vila, Vanuatu
615km (382mi) N of We, New Caledonia
760km (472mi) N of Dumbea, New Caledonia
760km (472mi) N of Paita, New Caledonia

Technical Details

A break in neighboring cities' water main created a 20-foot hole and closed the city's busiest intersection for three weeks.

On the morning of June 22, the bottom of a 36-inch water main in the heart of Robbinsdale burst, peeling back several feet of concrete-coated steel pipe like a can of sardines.

Over the next 40 minutes, an estimated 600,000 gallons of water blasted downward, creating a hole 20 feet deep at the city's busiest intersection.

"This is your worst nightmare," said Crystal City Engineer Tom Mathisen, who supervised the repairs. "It's always kind of hair-pulling, but yet, because we do this kind of stuff all of the time, there's a process to do it."

The complete repair and reconstruction of the giant Robbinsdale Sinkhole was finished in three weeks, an impressive feat considering the magnitude and complexity of the damage. Water gushing from the broken water main bored down 10 feet and destroyed a sanitary sewer line, which filled with sand and dirt. Then water, dirt and debris churned upward, taking out a storm sewer pipe that sat less than a foot above the water main.

The water continued to drive toward the surface, and eventually popped off several manhole covers, flooding the intersection of 42nd Avenue (County Rd. 9) and Bottineau Boulevard (Hwy. 81) around 10 a.m. In a stroke of luck, a nearby gas line was unscathed and no one was injured.

"I certainly have to commend the [various public works departments] for how quickly they turned the water off ... and then repaired it," said Robbinsdale Mayor Regan Murphy. "It was an amazing response - I mean, it was a 20-foot hole, and they had [Hwy. 81] open in two weeks,"

The repairs were especially tricky because the water main takes two slight turns near the break, one at a 45-degree angle and one at a 12-degree angle. The bends had to be replaced with custom piping, which was trucked in overnight from Dayton, Ohio.

"Thirty-six-inch ductile iron pipe is not something you just keep on your shelf," said Mathisen.

There was speculation that the blowout was related to the severe weather that ripped through the Twin Cities June 21-22, but city officials say that the break was probably a result of a leak that slowly built for years. Mathison pointed out clusters of pinholes around the spot where the 50-year-old pipe burst as evidence of it weakening over time.

Four months after he built a new, two-story brick house in his village in northern China's Shandong Province, Xiao Guoqiang was alarmed to find a huge crack on the living room wall.

Having seen homes in neighboring villages sink, Xiao realized his long-held fears were coming true.

"I knew the day was coming, but I didn't expect it to happen so soon," said Xiao, who has been forced to move from the land -- on which four generations of his family have lived -- as a consequence.

Xiao's hometown, Jining, is one of China's "coal cities," whose mineral wealth helps light up the night skies of the world's most energy-hungry country. The land here is honeycombed with coal mines, which can form massive sinkholes that leave thousands of homes uninhabitable every year.

Russia, which lost 25 percent of its grain harvest to drought last year, will see production restricted again this season as drought in parts of the country's European area and cold, wet conditions in Siberia damage crops, producers said.

Russia will have about the same total grain supply in the 2013-14 season that began July 1 as last year at about 85 million to 90 million metric tons, said Pavel Skurikhin, president of the country's Grain Producers' Union, at a briefing in Moscow today.

Supplies will include a harvest of 75 million to 80 million tons after drying and cleaning, imports and carryover stocks, said Skurikhin. Last year, Russia harvested 70.9 million tons, according to state data. With imports and carryover stocks added, total supply was about 90 million tons in 2012-13, according to Skurikhin. Grain exports are seen similar in both periods at about 15 million tons.

Russian farmers increased the area under grains this season by 500,000 hectares (1.24 million acres), according to Agriculture Ministry data. Drought in the Volga and Rostov areas in Russia's European area, as well as sowing delays in Siberia resulting from low temperatures and rainfall, will prevent farmers from expanding the crop by the 34 percent targeted by the Agriculture Ministry, according to Skurikhin.

Scotland's seabirds continue to struggle

The coldest spring in more than 50 years has taken a toll on Scotland's seabirds as early monitoring shows adult birds have arrived late for the breeding season and in poor condition.

Harsh winter

Harsh weather conditions earlier this year have added to the considerable long-term challenges seabirds face including lack of food due to the impact of climate change on the marine food chain, and poor management of human activities in the marine environment.

Kittiwakes, guillemots and razorbills

Colony counts on RSPB Scotland reserves across the country from the Northern Isles of Orkney and Shetland to the Firth of Clyde, reveal a similar picture with species like kittiwakes, guillemots and razorbills showing some of the steepest declines in number of birds present.

Thousands of birds have flocked to a town in Australia, causing power cuts and a mess, its mayor says.

Around 2,000 pink galahs and white cockatoos have descended on Boulia, Queensland, as a result of the drought, Mayor Rick Britton said.

They have been perching on power lines, causing outages when they take off, he said.

The birds may not leave until November when rain is due, he said, so "people are going to have to live with it".

As sunrise brings fresh light to the aftermath of strong storms in southern Kansas from Tuesday night, authorities are beginning to assess the toll. Hail as large as baseballs was reported in east Hutchinson, according to Reno County Emergency Management. Winds estimated as high as 100 miles an hour were reported in southern Reno County near Pretty Prairie. The town itself was hit hard by hail and strong winds, knocking down trees and blocking streets. "Please Please Please stay away from Pretty Prairie for now. They are not letting people into town at this time," a post on Reno County Emergency Management's Facebook page implored. A hail stone measuring 4.75 inches in diameter fell near Yoder in eastern Reno County and hail as large as tennis balls was also reported.

On July 14, a low pressure system that started in the Eastern United States retrograded under a ridge of high pressure to the north over the last couple of days. This storm system moved from east to west, which is extremely unusual for this hemisphere. We've seen these move east to west for a short period of time, but this one will make it to Southern California by the time it weakens. The upper level system is known as an easterly wave; however I'd like to call it a super easterly wave based on the distance it is going to travel. This particular system will have traveled from one side of the country to the other once it has stopped moving west, diving from there into Mexico, gathering up monsoonal moisture to be put into Nevada and Southern California later in the week into next week. Rainfall estimations across parts of Central Texas could be over 2-4″ of rain, with more rain (above 6+" possible in parts of South-Central Texas. Severe storms, including tornadoes, hail, and damaging winds will be possible from Texas, New Mexico, and parts of Arizona through the next few days. - The Weather Space

The mass of polar air that passed through Argentina before coming to Brazil at the end of last week dropped snow in at least 87 cities of Paraná, Santa Catarina and Rio Grande do Sul.

The cold wave, which reaches South, Southeast, Midwest, and up to two northern states of the country (Rondônia and Acre), is the longest in 13 years, according to the National Institute of Meteorology (Inmet).

"Should greatly disrupt agriculture"

"There were 17 days in all. Now, there are already seven days with temperatures below zero, and certainly this will continue until Friday, which should greatly disrupt agriculture, especially citrus plantations and lettuce, and bring problems health," says meteorologist Lucia Gularte of Inmet.

Among the places hit by the snow are two capitals: Curitiba and Florianópolis. In Curitiba, the record snow made on Tuesday by Simepar Meteorological Institute is the first since 1975.