2007 North America South and Eastern heatwave

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. The heatwave expanded eastward starting at the very end of July and lasting into the first weeks of August. This heat wave was notable for both associated severe drought over a large swath of the southeastern United States, and parts of the Great Lakes region, and its late season ending, with temperatures continuing, although more sporadically, well into the 90s °F (30s °C) into September and October in the mid-Atlantic region.

Environmental impacts

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 above 100 °F (38 °C)s as far north as Kansas City, MO and St. Louis, MO. At Raleigh-Durham, North Carolina, on August 9 and 10, the temperature reached 104 °F (40 °C).^[1] Much of the east coast experienced highs topping out around the century mark like at Charleston, SC and New York City, NY. Dew points reached the mid 70s °F (24 °C), creating a Heat Index values of 108 °F (42 °C) 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. August 2007 turned out to be one of the 20 warmest Augusts for the United States since 1895.^[2]

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]

Deaths and health impacts

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 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.

Meteorological setup

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 the offshore Atlantic. This in turn created an Omega block pattern over the central US and caused extreme heat to build for weeks, in some cases. The ridge eventually retrograded back towards the west which allowed some short term relief for the northeastern states and Mid-Atlantic, but in the Mississippi River Valley and southeast there remained oppressive heat for at least several more days. Some more widespread relief came by the end of the September, but before long much warmer the normal conditions returned across eastern North America by the first week of October, this time shattering long held records through to the end of the end of that month and finishing as the warmest October in 5 states in the region.^[2] August 2007 turned out to be one of the 20 warmest Augusts for the United States since 1895.

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External links

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