Effect of Tropical Cyclone Characteristics on Extratropical Rossby Waves in Ensemble Model Forecasts

This thesis revisited a previous topic on how the downstream and/or large-scale midlatitude response to a recurving TC potentially depends on the strength and/or location of the TC. This study differs from what Brannan and Chagnon (2020) in that this analysis examines ensemble forecasts for individual cases, thus controlling for the high variance in large-scale circulations that occur between different cases. The two cases focused on in this study are Tropical Cyclone (TC) Sandy (2012) and Tropical Cyclone (TC) Irene (2011). The question answered in the completion of this project is: How does the location and strength of a TC affect the forecast downstream? It was found that the nature of the interaction/relationship between the strength and location of a TC and how it affects downstream wave behavior is highly case sensitive. A large, statistically significant modification of the large-scale wave pattern was found for TC Sandy. The sensitivity of the wave pattern to TC characteristics was contingent on the storm propagating far enough north to affect the jet. The interaction in TC Sandy may have been advantaged due to its occurrence during the fall months (strong jet stream that is located not as far north). Specifically, the latitudinal location and MSLP anomaly magnitude (strength) of TC Sandy greatly affected the waves observed downstream. On the other hand, TC Irene showed less of a relationship between the strength/location and the downstream wave behavior. This was thought to be due to a lack of a strong jet stream that was located too far north to be affected by TC Irene. Nevertheless, TC Irene did exhibit an impact on the downstream wave behavior and the location and strength of the storm. The main takeaways of this project are that 1) downstream midlatitude effects from a TC are contingent on the location and strength of the TC, and 2) the strength of the interaction is case dependent. Meaning there might be more similarities between TC Irene and TC Sandy if they were occurring in the same season, instead of the latter being in the fall and former being in the summer.