Identification of large-scale flow patterns conducive to extreme temperatures over the central and eastern U.S. as applied to the late June and early July 2012 heat wave event

The late June and early July 2012 U.S. heat wave event produced thousands of new weather and climate records over the central and eastern U.S. For example, the heat wave event was associated with a record 11 straight days with temperatures of 35.0C (95.0F) or higher at Washington, D.C. The heat wave event was also associated with large impacts to the energy and agriculture complexes. Between mid-June and mid-July, the New York spot price of natural gas increased ~40% from ~$2.30/MMBtu to ~$3.30/MMBtu and the price of corn increased $300 from $520/Bu to $820/Bu. The heat wave event contributed to the highest percentage ratings of ‘very poor' and ‘poor' corn condition (~50%) since 1988 over the central U.S. The objective of this presentation is to specifically investigate the evolution of the large-scale flow pattern that produced the late June and early July 2012 heat wave event over the central and eastern U.S.

The late June and early July 2012 heat wave event ranks in the top 0.1% of extreme warm-season temperature events over the central and eastern U.S. between 1948 and 2012. Similar to previous extreme warm-season temperature events, the most prominent large-scale flow pattern associated with the 2012 event was a broad subtropical anticyclone that amplified over the Intermountain Western U.S. and progressed eastward to over the central and eastern U.S. This presentation will additionally highlight the processes that contributed to the eastward displacement of the subtropical anticyclone and discuss upstream variability in the large-scale flow over the North Pacific as an antecedent to the late June and early July 2012 heat wave event.