This research aims to understand the predictability of heavy precipitation events and improve ensemble forecasts of these events by employing SPPT to convective-resolving WRF forecasts. Two case studies from different parts of the world, but similar synoptic characteristics (i.e., moist southwesterly flow from the deep tropics), are studied. The first case is the remnants of Tropical Storm Lee, which brought heavy rainfall to New York on 6-8 Sep 2011, while the second case is a Meiyu-related heavy rainfall event in Taiwan on 16 June 2008 during SoWMEX-IOP8 in 2008. The talk will document the sensitivity of probabilistic forecasts of these events to modifications in the SPPT parameters (i.e., perturbation length and time scales, and amplitude). In addition, the independent SPPT (iSPPT) scheme will be used to understand how internal uncertainty in the microphysical, radiation, and PBL parameterizations modulate the predictability of these events.