Synoptic-scale precursors to the extratropical transitions of tropical cyclones that impacted the Northeast: an analysis of Irene (2011), Sandy (2012) and Andrea (2013)

Tropical cyclones (TCs) of varying shapes, sizes and intensities form in nearly every ocean basin and subsequently impact numerous heavily populated areas. Often, the level of interest in a TC diminishes once it moves poleward into higher latitudes and begins to lose its tropical characteristics. Over land, tropical systems can interact with a variety of synoptic, mesoscale and topographic features that result in either the weakening of the TC or a transition into an extratropical cyclone (EXTC). Many TCs typically weaken and decay soon after landfall due to generally unfavorable conditions such as increased friction, moisture loss and baroclinicity. However, given the proper synoptic setup, a weakening TC could transition into a fast-moving EXTC and extend TC-like conditions such as intense rainfall and hurricane-force winds over a broad area at latitudes that do not typically experience these conditions. The Northeast was recently impacted by three EXTCs in three consecutive years – Irene (2011), Sandy (2012) and Andrea (2013), all of which produced TC-like conditions. The synoptic-scale conditions leading up to the TC's transition and shortly thereafter were analyzed. Cyclone phase space diagrams were utilized to determine the time each TC transitioned into an EXTC. ArcGIS was used to analyze societal and environmental impacts produced by each storm.