92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012
Anticipating the 15 and 26-27 April 2011 Tornado Outbreaks Using Ensemble Model Output and Pattern Recognition
Hall E (New Orleans Convention Center )
Chad Entremont, NOAA/NWSFO, Jackson, MS; and B. Bryant

This study will focus on the potential for long-lead time anticipation of significant severe weather outbreak events. When looking at lead times, the National Weather Service focuses on the warning and watch phase of operations when severe weather is likely or occurring. In dealing with potential severe weather outbreaks, the outlook phase can also be a valuable tool in preparing emergency management partners and the public for potentially life-threatening weather in the days ahead. By using pattern recognition of past significant severe weather episodes and historic outbreaks, one can determine a favorable “parameter space” to support such impactful events. In addition, the location of certain synoptic features and severe weather parameter maxima play a critical role in the ultimate magnitude and location of the event. Using examples from past events, specific parameter spacing most supportive of significant severe storms and associated strong to violent tornadoes will be discussed and defined. We will show how long-lead (e.g., on the order 2 to 5 days) ensemble mean forecasts can identify areas of critical defined parameter spacing to infuse confidence into a forecast of significant severe weather. A review of recent and deadly tornado outbreaks from 15 April and 26-27 April 2011 will be incorporated to show how NWS Jackson developed sufficient forecast confidence to use enhanced wording in the forecast and outlook products, days in advance.

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