July 18, 2013 in Washington Voices

Weather: ‘Heat bursts’ radically change temperature in moments

 

On June 11, there was a rare 26-degree “heat burst” at Grand Island, Neb. The temperature at 2:53 a.m. was 73 degrees, but skyrocketed to 99 degrees at 5:10 a.m., before the sun came up. The phenomenon responsible for the sudden rise in temperature, especially at night, is a called a heat burst.

These rather rare and interesting events are usually associated with thunderstorm activity, which can also feature quick drops in temperature of 20 to 30 degrees or more in just a few minutes.

Heat bursts, or flashes as they’re sometimes called, often occur just before the arrival of a severe thunderstorm, just ahead of the heavy rains, strong winds and, frequently, episodes of large-sized, crop-damaging, window-breaking hail.

Most heat bursts occur at night when relatively cool air contrasts with a sudden rush of much hotter air trying to rise off heated surfaces. The colder, denser air often wins this air mass battle, forcing the warmer air back toward the ground.

Many of the heat bursts don’t make the record books, because they often don’t occur at official government weather stations. But there are some examples of well-documented heat bursts around the world.

For example, in Turkey on July 10, 1977, the temperature in the shade briefly soared to 152 degrees Fahrenheit at Antalya in just a few minutes late in the afternoon.

On July 6, 1949, according to local observers, a thermometer near Lisbon, Portugal, registered an incredible 158 degrees Fahrenheit for about 30 seconds.

In the U.S., according to the Minneapolis Tribune, “a huge blast of hot air pushed through portions of New Ulm and Renville County on July 10, 1879. Although the heat only lasted for a minute or two, it was so intense that people rushed out of their homes thinking them to be on fire!”

In Texas, just after midnight on June 15, 1970, a blast of very hot wind – estimated at 80 to 100 mph – drove the temperature from 70 to 140 degrees near Waco. Cotton fields were reported “to have been carbonized.”

Closer to our region, on Sept. 9, 1994, the temperature at Great Falls, soared from 67 degrees to 93 degrees in just 15 minutes between 5:02 a.m. and 5:17 a.m. By 5:40 a.m., the temperature was back down to 68 degrees after tying the record high for the date.

Around the Spokane and Coeur d’Alene area, I’ve never observed or heard of a major heat burst, but I’ve seen several occasions when the mercury fell by as much as 20 degrees or more in a few minutes following the arrival of either an Arctic invasion or the passage of a spring or summer thunderstorm.

In terms of our Inland Northwest weather, it still looks drier than normal until at least mid-to-late September due to a large stationary ridge of high pressure. We’ll see more 90-degree-plus days between now and the end of August.

If you have any questions or comments, you can contact Randy at www.facebook.com/wxmann, or go to www.longrangeweather.com for additional information.


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