Research: Predecessor Rain Events ("PREs") ahead of recurving tropical cyclones

Working with Tom Galarneau and Lance Bosart of the University at Albany, Dr. Schumacher has analyzed heavy rainfall that can occur ahead of, but far removed from, a recurving tropical cyclone. Tropical cyclones bring deep tropical moisture with them when they make landfall, and this moisture can, in some cases, move far out ahead of the cyclone itself. If this moist air is lifted (along a front, for example), heavy rains may result.

One prime example of this effect was ahead of Tropical Cyclone Erin, which made landfall in Texas and moved poleward into Oklahoma in 2007. Erin was not a particularly strong system, only reaching Tropical Storm intensity at landfall. (However, the remnants of Erin later reintensified over Oklahoma, which is another topic of ongoing study.) Ahead of Erin, deep tropical moisture moved northward into the Midwest, where it encountered a slow-moving front over Minnesota and Wisconsin. The tropical moisture added to a situation that was already favorable for heavy rains, and record rainfall and flash flooding occurred in southeastern Minnesota and southwestern Wisconsin.

A paper showing the climatology of these "PREs" and an analysis of the PRE ahead of Erin was recently published in Monthly Weather Review. Furthermore, another paper, in which we quantify the importance of the tropical moisture, was also recently published in Monthly Weather Review.

Refereed publications on this subject

• Galarneau, T. J. Jr., L. F. Bosart, and R. S. Schumacher , 2010: Predecessor Rain Events ahead of tropical cyclones. Monthly Weather Review, 138, 3272--3297.
• Schumacher, R. S., T. J. Galarneau, Jr., and L. F. Bosart, 2011: Distant effects of a recurving tropical cyclone on rainfall in a midlatitude convective system: A high-impact Predecessor Rain Event. Monthly Weather Review, 139, 650--667.
• Schumacher, R.S., and T.J. Galarneau, Jr., 2012: Moisture transport into midlatitudes ahead of recurving tropical cyclones and its relevance in two predecessor rain events. Monthly Weather Review, 140, 1810-1827.

This material is based upon work supported by the National Science Foundation under Grant No. AGS-0954908. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.