Wednesday, 25 January 2017
4E (Washington State Convention Center )
An exceptional drought overspread much of the southern High Plains, including most of Oklahoma and Texas from 2011 through 2014. The summers were characterized by exceptional dryness and record setting heat waves, which led to extreme wildfires, decreased crop yields, livestock reduction, and severely depleted reservoirs. Total monetary losses due to drought in Texas alone were estimated to be near $10 billion. Composite anomalies for the summers of 2011-14 were calculated for various atmospheric parameters, including 500 hPa height, 850 hPa temperature, 750 hPa temperature, outgoing longwave radiation, surface relative humidity and soil moisture. These parameters were compared to the 85th percentile of wettest and warmest years and the 15th percentile of driest and coolest years. The composites for 2011-14 were all similar to those of the most extreme warmest and driest years, and the exceptionally dry conditions of 2011-14 contributed to the large temperature anomalies observed through the summer. In contrast, the coolest and wettest years tended to exhibit more significant differences than similarities in these parameters when compared with either 2011-14 or the warmest and driest years. By comparing extreme anomalous years to 2011-14, similarities can be determined which contribute to these abnormal conditions. Therefore, forecasters can better anticipate exceptional conditions based upon particular forecast parameters.
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