2011 Heatwave Size, Extraordinary Heat/Humidity Set It Apart - Moorehead MN Heat Index 134F 7/20

[hatrack]

EDIT

The heat wave that is currently roasting much of the United States stands out from typical summertime heat events that we expect to occur during July and August. First of all, the hot weather, which is associated with a sprawling area of high pressure, covers a huge expanse. Today, for example, at least 141 million people under heat advisories or warnings, according to a tweet from NOAA spokesman Justin Kenney (see video below).

Second, the heat wave has featured an extraordinary combination of high temperatures and humidity. In combination, these are known as the heat index, and during this heat wave the heat indices have shot up to levels more commonly seen in the brutally hot and humid region near the Red Sea, rather than in Minnesota and South Dakota. As meteorologist Paul Douglas reported on his Minneapolies Star Tribune blog, the heat index in Moorhead, Minn. hit a whopping 134°F yesterday, likely setting a new record for the highest heat index ever reported in Minnesota. The Twin Cities also tied its all-time heat index record, at 119°F.

These extreme heat indices constitute a human health risk, since these conditions make it extremely difficult for the body to cool itself through sweat and evaporation. The extra humidity makes evaporation more difficult, which effectively shuts down our main cooling mechanism. The dew point (another measure of how much water is in the air) has reached the 80s across many parts of the Midwest, which is a level more commonly seen near the Gulf of Mexico during the summertime. For example, Douglas reported that Minneapolis experienced three days in a row with 80°F or higher dew points. According to him, that is unprecedented since the beginning of instrument records there in the late 19th century. In Moorhead, Minn., where the record heat index was observed, the dew point reached 88°F, a new state record.

These dew points are partly related to the heavy rains and flooding that the Midwest experienced this spring. As temperatures soared this week, more and more water evaporated from the moist soils and corn fields, elevating the humidity levels higher than they would normally in a typical summer heat wave. It's no accident that there is a lot of overlap between the highest heat indices seen in the first map below, and the Midwest portion of the spring flood outlook from the National Oceanic and Atmospheric Administration (NOAA).





EDIT

http://www.climatecentral.org/blogs/hot-nights-and-high-humidity-set-this-heat-wave-apart/

[phantom power]

1. I don't think we've ever had a heat index of 134F, here in AZ.

Might be wrong. Highest recorded temp is 128F, and our humidity is generally too low to raise the heat index significantly higher than the actual temperature.

[XemaSab]

7. Apparently 134 is the record for North America

Death Valley in 1913. But it's so arid there I bet it was just 134 with no heat index.

A brutal second place record was set in Goleta, California, in 1859. Due to Santa Ana/Sundowner winds, the temperature went up to 133 in a few minutes. Cattle were suffocated in their tracks, and virtually all the plants were killed. This was right on the coast. Usually it's about 70 there year-round.

[pscot]

2. If this isn't GW

what will GW be like?

[grasswire]

3. here in the PNW, urban planners are planning for climate refugees.....

...to overwhelm our cities and public services.

Just great. Those of us whose parents and grandparents planned ahead and settled in temperate climate will be crowded out soon.

[swishyfeet]

6. I'm not so sure anyone wants our weather either

While the midwest is sweltering, we've had the most gloomy weather I've ever seen in my 40 years here - over the past year.

I can't stand it.

[NickB79]

4. Stepping out of the house into that wet heat felt like hitting a wall

You could physically feel the air was thicker, more dense. I'm in the Twin Cities, MN, and it's been BRUTAL here for the past few days. I made the mistake of planting some late-season pepper plants I bought on clearance at the garden center, and after 20 minutes I was soaked with sweat and on the verge of heat exhaustion.

[stuntcat]

8. it's just oppressive

in Arlington. I went out to water the plants at 5:30, I knew I had to do it early as possible, and when I finished I was soaked. Went out a few hours later and the air was even harder to breathe.

[damntexdem]

5. Hey, we've had a real cold snap here in north Texas.

Highs under 100 -- 98 out right now.