Aug 08

Heat index just hit 165 degrees in Iran (MSNBC, Aug 4, 2015):

The 1995 Chicago heat wave brought a misery of triple-digit deaths and extreme temperatures. The mercury soared to 106 at Midway Airport, a record for Chicago, and the heat index – a humidity gauge that estimates what it actually feels like outside—hovered in the 120s.

Keep that grim benchmark in mind as you consider the following confirmed heat index data for Bandar Mahshahr, Iran, a city of 100,000 people on the Persian Gulf. The effective temperature hovered in the mid-triple digits for a week, rising to an egg-cooking, brow-scorching 165 degrees Fahrenheit this past Friday. That’s one of the hottest days humanity has ever recorded.

It’s a “very rare” event, Nick Wiltgen, a senior meteorologist at The Weather Channel, told msnbc. But one of his colleagues at the Weather Underground has actually seen higher: On July 8, 2003, the heat index reached at least 176 degrees Dhahran, Saudi Arabia.

Both temperatures are literally off the charts. The heat index, developed in 1979, inputs air temperature and dew point to estimate the “feels like” figure for a given day. At the time, however, the highest heat index that researchers were capable of imagining was 136 degrees—which is an air temperature of 110 degrees and a dew point of 80.

Iran beat the chart by a wide margin, with air temperatures 115 degrees and a dew point of 90. The heat index is not an official statistic tracked by governments, so international records are hard to confirm. In the U.S., however, the highest heat index Wiltgen has ever seen is 144 degrees in Sheldon, Iowa, on July 29, 1999.

What does that kind of heat actually feel like? The Washington Post’s Capital Weather Gang posted a first-person account from a reader who lived through Saudi Arabia’s 176 degree day in 2003.

“When the winds come off the Persian Gulf you just can’t imagine how awful it gets,” the reader wrote. “You’d walk outside and it felt immediately like someone pressed a hot wet towel, like you sometimes get on airplanes, over your entire head. I wear glasses, and they’d immediately fog up. You sweat instantly.”

Remarkably, this kind of heat is more or less normal for the Persian Gulf, an area that doesn’t need climate change to get crazy hot. Residents who can afford it live under a dome of air conditioning. Many others become nocturnal, sleeping through the heat, and using the night for work or play.

They are used to the swelter of summer, because the region’s unique geography guarantees triple-digit temperatures and moist air. “The clear skies let the sun roast the land masses, bringing 110º+ heat,” said Wiltgen.

But the Persian Gulf gets heated up as well, and the rising moisture wafts over the land like a wet, wool blanket.

There’s mixed relief in sight, according to The Weather Channel, which predicts a shift in wind and reduction in the humidity by Saturday. That will reduce the heat index. The air temperature, however, is expected to rise to 117 degrees.

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