Wow, it’s hot!

It continues to be really hot in the central part of the US. The thermometer at our house says 98 F (37 C) today which is July 4, 2012. The number of 90 F (32 C) plus days this year has been high as well. There have been 8 days about 90 F (32 C) a my house in Temperance, MI so far this June and July. Toledo has had 12 days 90 F (32 C).

Last week I took some surface temperature observations using the GLOBE protocol for infrared thermometer. I measured the temperature of a parking lot with a cover of asphalt, a grassy area and an area with bare soil where the ground had been dug up. Which one do you think was the hottest? The grass was 34 C (94 F), the asphalt was 52 C (126 F) and the bare soil was 64 C (148 F). I didn’t expect the bare soil to be so hot.

NASA has produced a temperature anomaly image from satellite imagery (see below). The red shows areas where the temperature was above average and the blue shows temperatures below average for June 28, 2012. You can see that a large part of the US was red, above average.

This heat has dried things out as well. I have been watering my garden every day. I really enjoy growing our own food. I knew it was dry because there was an area of the garden that the sprinkler missed watering. In that spot, even the weeds were dried up.

The Palmer Drought Severity Index in the image below shows that large parts of the United States are in drought right now. In fact, in northwest Ohio and southeast Michigan where I live, we have severe to extreme drought conditions.

Yesterday, a friend of mine posted on Facebook that he saw a fire in the forest near his house in Michigan. In this dry, hot weather, brush fires can easily start anywhere. He called 911 for the fire department to put it out. That was a wise thing to do. If you come upon a similar situation, tell an adult and/or call 911.

The fires in Colorado are related to this dry weather. The satellite image below from the MODIS sensor on the Terra satellite shows the current fires out west from NASA. Colorado has clouds over the mountains so the smoke from the fires is not visible.

Why is it so hot? The upper atmosphere has been stuck in a pattern with a ridge over the center part of the US (see image below). This is a common summer time pattern with troughs over the western and eastern US. But, this summer it has been particularly persistent and hot. The troughs on the east and west coasts have kept those locations relatively cool. This image is the 500 mb map that is about 10 km (6 miles) above sea level. It is made by the National Weather Service using balloon observations at 0 UTM and 12 UTM

Stay cool. Stay in the shade if you are outside and drink lots of water. Heat stroke is very serious.
Dr. C

Posted June 29, 2012
Today was one of the hotter days that we have had in Toledo in a long time. The maximum temperature was 97 F (36 C). It is hot from the Rockies all the way to the east coast of the United States. On Sunday and Monday of this week, I was in Boulder, Colorado. The temperature reached 104 F (40 C) on Monday. What was interesting was that people were still out exercising or talking on the street. I had a really hard time believe that they could do it. But, to be honest, although it was hot, it did not seem oppressively hot. The reason was that the relative humidity was about 10%. The relative humidity is the ratio of the actual amount of water vapor in the air to the amount of water vapor the air can hold given its temperature. Warm air holds more water vapor than cold air with the amount increasing exponentially as temperatures get warmer. No wonder the relative humidity was so low. It was partly due to the temperature being so high and partly due to the low amount of water vapor in the air. Today in Toledo, the temperature was 95 F (35 C) but it felt much hotter. The relative humidity was about 40%. That means there was quite a bit of water vapor in the atmosphere. 40% relative humidity would still be considered pretty dry.

Below are the warnings on Friday, June 29, from the National Weather Service. You can see that there are large areas that are red in the image are heat warnings or fire warnings over large areas of the central US.

In Toledo, it is quite dry as well. The grass is all brown. In fact, the National Weather Service office has issued a fire warning for the area. This area is not known for its wildfires. You probably have heard by now of the devastating wild fires that are going on in Colorado. They have gotten worse since I came back. .

The forecast is for the heat wave to continue.