Thursday, July 21, 2011

The Heat Dome

    We have been hearing about a weather phenomenon which I had never heard named before. It is an extended and severe heat wave that is centered in the Central United States and has been named, "A Heat Dome."  Basically it is a very high pressure area which is trapped in the middle of the United States, over the prairie states: Kansas, Oklahoma, Missouri, Iowa and Illinois. It has trapped very hot and humid air up from the Gulf of Mexico, compressed it, heating it up even more. It then expanded to include Wisconsin, Minnesota, Indiana and it is now slowly drifting eastward. A combination of factors combined to produce this strange (to me) meteorological phenomenon. First the high pressure in this Midwest area was indeed very high so that no weather systems trying to move in from the West were strong enough to move it on. Also the jet stream is very far north and fairly weak at this time of year. So prevailing winds could not move it out. Thirdly there was a mild tropical storm area off the Southeast of the United States and that was blocking this high pressure system from spreading to the southeast. The humidity was especially high during this phenomenon because of all the recent wet weather and flooding in the upper Midwest, adding to the humidity in the air. Apparently "heat domes" are not rare, but it is rare for one to be this large (affecting 30+ states) and this long lasting (so far 5 days, probably up to 7 or 8.)
     Characteristics of this "Heat Dome" in the Milwaukee area are absolute temperatures in the 90s and in some areas even up to 100, and humidity levels of 70% and 80%. Heat indices (the combination of the temperature and the humidity) make a human feel like the temperature is much higher, well into the hundreds, as high as 115 and 120 in some areas. The Midwest has had at least 13 deaths directly related to the heat through these last 5 days. The heat is going to continue in the Midwest but the humidity has gone down some. Temperatures will be in the upper 80s in Wisconsin through the weekend. But now this heat phenomenon is spreading to the eastern states. 
     Since record deaths occurred in the Chicago area during a protracted heat wave in 1995, our city took all sorts of precautions. Various air conditioned cooling centers were opened. The libraries opened early and stayed open late as did the various pools and other water features. Multiple warnings were issued on TV and radio, suggesting that people try to get to a cool place for several hours each day. The signs and symptoms of heat injury were played and replayed.
     Well we were not satisfied to just sit at the edge of this phenomenon. My husband and I along with my sister had planned to take my 93 year old mother down into central Illinois to visit my aunt, my father's sister who is in a nursing home down there. We debated whether to cart this 93 year old woman along with us. The news media is constantly issuing warnings about the elderly during this heat wave. She saw no reason for concern and wanted to go. We would be fine in an air conditioned car, restaurants, motel, home, and nursing home. But what if something went wrong with the car. We have a car in good condition, but you never know. Well, we decided to treat it as though it were in the dead of winter, except the precautions we took were just the opposite. We packed all sorts of containers and coolers with ice water, cold beverages and ice cubes. I took towels and handkerchiefs we could moisten with the ice water and put around our neck. I carried umbrellas to provide shade because we certainly would not be able to sit in a disabled car without the engine and AC running. My AAA membership is up to date and I charged my cell phone up. We could only hope that if our car became disabled, the AAA or other authorities would be quick to respond.
      So we drove down into the "HEAT DOME"! When we arrived at our destination, the first thing we did was check into our motel to make sure their air conditioners were up to par and they were. Well, everything went OK. We visited the ill aunt, and spent time visiting with her daughter and her family in their nicely air conditioned home. Our cousin offered us the use of their outdoor swimming pool but she said the water was the temperature of bath water. Some did take advantage however. We drove back home today. When we got to Milwaukee, we learned that a weak "cold" front had moved through. The temperature was 89 degrees and the humidity level was down to 68%. I called my mother, told her we had made it home after dropping her off, and that we were so chilled that we had put on our sweaters. Sarcasm! Well the heat warnings have left the State of Wisconsin but it is still going to be in the upper 80s and very muggy the next 3 days at least. 
     We usually set our air conditioner to about 75 degrees, but we have ceiling fans in every room. Running them makes 75 or 76 degrees feel much cooler. For anyone building a new home, that would be my strongest recommendation -- buy fans. Well, I now need to go out in the cooler early evening air and water my poor potted plants. They must wonder what's going on. They sometimes need watering 2-3 times a day in this heat especially if there is a hot wind blowing.

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