Southeast US Extreme Precipitation Events Footprint in Inter-Annual Variability

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Monday, 18 January 2010
Steven C. Chan, Florida State University, Tallahassee, FL; and V. Misra

Handout (257.8 kB)

A detailed analysis is performed to better understand the interannual and sub-seasonal variability of moisture sources of major recent dry (1980, 1990, 1993) and wet (1989, 1994, 2003) June-July-August (JJA) in the southeastern United States. Wet (dry) JJAs show an increased (decreased) standard deviation of daily precipitation. While most days during dry JJAs have little or no precipitation, wet JJAs contain more days with significant precipitation and a large increase of heavy precipitation days. At least two tropical cyclone/depression landfalls occur in the southeast US during wet JJAs, while none occur during dry JJAs. The trajectory analysis suggests significant local recycling of moisture, implying that land-surface feedback has the potential to enhance (suppress) precipitation during a wet (dry) JJA. Remote moisture sources during heavy precipitation events are quite similar between wet and dry JJAs, but such events are far more common in wet JJAs. During the wet (dry) JJAs, heavy precipitation events contribute to more (less) than half of the JJA precipitation total.