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Using Standardized Anomalies to Identify Significant Heavy Rain Events. Jason Krekeler And Richard H. Grumm National Weather Service State College, PA. Motivation. Record rainfall with remnants of TS Lee Look at key features of this event Pattern and persistence of the pattern
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Using Standardized Anomalies to Identify Significant Heavy Rain Events Jason Krekeler And Richard H. Grumm National Weather Service State College, PA
Motivation • Record rainfall with remnants of TS Lee • Look at key features of this event • Pattern and persistence of the pattern • Pattern similar 9/30 – 10/1 2010 event and others • Compare these events
How do these events compare? • Similarities • Deep trough in eastern US • Anticyclone in North Atlantic • Surge of tropical moisture along frontal boundary • Differences • Deepening surface low vs cut off upper level low • T bone vs north/south bands • duration
Persistance • Both events featured a 24 hour period of intense rainfall • Deep southerly flow • High precipitable water • Jet entrance regions • Downstream blocking ridge
Comparison • Similar rainfall pattern- north/south bands • Sep 7, 2011- • Higher rainfall totals • Stronger frontal boundary • More focused band of high pw • Sep 30,2010 • broader area of heavy rain • Stronger southerly flow • Ridge further off the coast
Conclusions • Large scale patterns similar but differences in the details • Persistence of the pattern • Similar pattern of rainfall but differences in magnitude and scale • If TC Katia was not there…? • Would the LLJ been broader/stronger with broader area of high PW and heavy rain