New York City to Be Hit by Another Heat Wave Starting Today Into Next Week

New York City is starting out on another heat wave today that will likely last into at least early next week, according to the National Weather Service.

A heat advisory has been issued for New York and an air- quality alert stretches from Connecticut to Maryland and Delaware, according to the weather service. An advisory is issued when temperatures are expected to reach 95 Fahrenheit (35 Celsius) for at least two days or are likely to hit 100 or more.

“The heat continues into Monday in the low- to mid-90s,” said Brian Ciemnecki, a weather service meteorologist in Upton, New York. “We have a shot at falling below 90 on Tuesday, but there will be at least four hot days here.”

A heat wave is defined as at least three days of 90-degree or higher readings.

Above-normal temperatures have been gripping a large part of the U.S. for the past few weeks, as well as portions of Asia and Europe including Germany, France, China and Japan, taxing utilities and setting temperature records. New York broke daily heat records last week when the temperature passed 100 two days in a row.

Natural gas for August delivery lost 4.3 cents, or 0.9 percent, to $4.543 per million British thermal units at 10:20 a.m. on the New York Mercantile Exchange. The futures have fallen 18 percent this year.

One of the culprits for the heat has been the Jet Stream, a narrow band of strong winds in the atmosphere, which has been farther north than usual, said Jim Rouiller, a senior energy meteorologist at Planalytics Inc. in Berwyn, Pennsylvania.

The Jet Stream divides northern cool air and warm southern air as it circles the world. Along its twisting edge, disturbances develop that help moderate temperatures.

Abnormal Path

“The problem is that over the past six weeks the Jet Stream has been abnormally far north and it hasn’t had any drops that would support cold switches,” Rouiller said by telephone yesterday. “It has allowed warm air to push steadily north and intensify, and once this happens it persists.”

For the second time in two weeks, Consolidated Edison Co. today urged its 3.2 million customers in the New York City area to conserve power during the day.

“With the next heat wave looming and temperatures expected to stay in the 90s this weekend, Con Edison is again emphasizing energy-saving steps to conserve,” according to a statement posted on the company’s website.

Degree Days

Since June 1, the cooling degree days value in Central Park has been 542, or 156 above normal, according to the weather service.

Cooling degree days, calculated by subtracting a base of 65 degrees from the average daily temperature, is a value designed to show energy demand, according to the weather service. The higher the value, the warmer the weather, and thus the more energy is probably consumed to cool homes and businesses.

An excessive heat watch also has been issued for Philadelphia, parts of eastern Pennsylvania, southern New Jersey and northern Delaware for later this weekend.

“The combination of hot temperatures and high humidity will combine to create a dangerous situation in which heat illnesses are possible,” according to a weather service bulletin. The advisory warns against leaving pets outside.

Temperatures are forecast to be in at least the mid-90s in Baltimore, Washington and Philadelphia into next week, according to the weather service. The high in Baltimore today is forecast to reach 99, and in Washington it may hit 97.

The cooling degree days value at Washington Reagan National Airport since June 1 is 727, or 207 above normal, and in Baltimore, 650, or 239 above normal. Philadelphia’s value has been 647 or 231 above normal.

To contact the reporter on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net.

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