Forecast Error Wavepackets in the Midlatitude Stormtrack associated with Recurving Typhoons

Tropical cyclones that move poleward often recurve and undergo extratropical transition. Typically, in addition to the structural transformation of the cyclone, a distinct wavepacket is excited within the mid-latitude stormtrack. Here, we examine the skill of an ensemble forecasting system within this developing wavepacket. We find that the ensemble standard deviation, a measure of potential forecast skill, is closely related to the developing wavepacket. This, and other aspects of the forecast error fields are investigated from the perspective of dispersing wavepackets in the midlatitude stormtrack. We report on the factors that constrain the amplification rate of the "error wavepackets" and the streamwise extent of the "error stormtrack".