The eastern United States heat wave of 3–8 July 2010

Heat waves have been identified as a significant cause of weather-related fatalities in the United States. Chagnon et al. (1996) documented the 1995 Midwestern United States heat wave, which caused 525 deaths in Chicago, and 830 deaths nationwide. The heat wave of July 1999 caused an estimated 309 deaths in 21 states, with the majority of the deaths occurring in the Midwestern United States in late July. Heat waves are not unique to the United States. A deadly heat wave struck Europe in the summer of 2003 claiming an estimated 35,000 lives. A prolonged heat wave struck northern Europe from 8-15 July 2010, breaking high temperature records set in 1753.

A sustained heat wave affected the eastern United States from 3-8 July 2010. This study will examine the conditions associated with this early season heat wave. The study will focus on the values and character of climatic anomalies, in order to enhance situational awareness in the extended through use of climatic anomalies. Data from previous heat waves, using analysis of the National Centers for Environmental Prediction (NCEP) Global Reanalysis data (GR), is presented. This event shared common characteristics of key variables associated with previously documented heat waves: a large 500 hPa subtropical ridge with a closed 5940 m contour, above normal 850 and 700 hPa temperatures, and a surge of anomalous precipitable water north and west of the heat affected region.

Predominantly west to northwest low level flow enhanced warming through downsloping, and may have limited the cooling impact of the Atlantic Ocean. This led to a large area of temperatures exceeding 37.8°C (100°F) from eastern New England to North Carolina on 7 July 2010. All the climatic stations in the New York City Metropolitan area set record high temperatures including a rare 37.8°C reading at Islip, New York on 7 July 2010.

It will be shown that the NCEP models and ensemble forecast systems provided 3-7 day lead-time as to the potential for this event. Key variables, such as 500 hPa heights, showed a high probability of exceeding critical values associated with previous heat events. This led to high forecast confidence in the predictability of this and potentially similar heat events, and may aid in assisting decision makers in taking measures to mitigate the impacts of heat waves in the future.