The 2007 North America South and Eastern heatwave was a continuation and eastward expansion of the 2007 Western North American heat wave which began in late June 2007. As expected the heat from that heatwave expanded eastward starting at the very end of July and lasting into the first weeks of August. This heat wave eventually ended towards the end of October 2007 in this region of the United States of America.
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The North American South and Eastern Heatwave was responsible for oppressive heat and building drought across the central and southern midwest and into the southeast. Temperatures were soaring into the upper 90s and low 100s as far north as Kansas City, MO and St. Louis, MO. Much of the south experienced highs topping out around the century mark as far east as Charleston, SC and New York City, NY. On top of the actual temperatures being high, the humidity levels were in the 50s to 60s percent levels, and dew points in the upper 60s to mid 70s created Heat Index values of 105 or more in much of the affected areas. For that reason, nearly two dozen states were in eitherHeat Advisories, or Excessive Heat Warnings or Watches, with the area of most watch or warning coverage in the Mississippi River Valley region from Illinois and Missouri down to Louisiana and the Southeast Atlantic Coast, as well as parts of the Mid-Atlantic.
13 new all time maximum high temperatures were set, along with several hundred new daily high maximum temperature records.[1]
Besides for the temperatures, the nature of the heatwave and the accompanying high pressure system area causing intensifying drought conditions, especially in areas that were already experiencing exceptional drought conditions, such as northern Alabama where the drought was exceptional even before the heat wave. It is also initiating drought conditions into the Ohio and Mississippi River Valleys. Depending on exactly how long this heatwave lasts, it could have a major impact on the agricultural harvest as September and October approaches. The drought conditions will also most likely create conditions that are more favorable for wildfires and create water shortages in some communities that are already dealing with low water levels. The persistent drought and heat wave have further decreased soil moisture to below 98-99% of normal levels.[2]
More than 50 deaths[3] were reported as well as cases of Heat exhaustion and Heat Stroke. Most occurred in the very elderly and people who could not afford air conditioning due to high energy costs. Fortunately these were sporadic cases, and most healthy people are handled the heat due to advance warning, and better preparation procedures. Most likely to be affected by the excessive heat were those working consistently outdoors, performing strenuous work, such as construction work, or other jobs requiring excessive pushing, pulling. It was been advised that people working these kind of jobs seek shade when possible, take frequent breaks, wear light colored, loose fitting clothing, as well as to drink plenty of clear non-alcoholic beverages even if they did not feel thirsty. Wearing sunglasses, sunscreen, and a wide brimmed hat weren't bad ideas either, as the UV or Ultraviolet index was expected to top at above normal levels due to the extra dry and hot weather.
The heat wave was triggered by several factors. First an unusually strong upper level ridge that has settled over the southern plains and southeast near the Ozarks. Another was the sharp troughing over the Pacific Coast and offshore of the Atlantic. This in turn created an Omega block pattern over the US and caused weather to persist for a period of days if not weeks in some cases. Weeks the ridge eventually retrograded back towards the west which allowed some short term relief for the northeastern states and Mid-Atlantic, but the Mississippi River Valley and southeast were not expected to get so lucky and stayed in the oppressive heat for at least several more days. Some more widespread relief came by the end of the following month. August 2007 turned out to be one of the 20 warmest Augusts for the United States since 1895.[2]