Extratropical cyclones - a forecaster's perspective

Abstract

Despite considerable improvements in numerical models in recent years, weather events associated with extratropical cyclones continue to present forecasters with a challenge. For most cyclogenesis events model forecasts display, at the least, subtle errors in track and intensity of the system. Occasionally, errors can be significant - a depression can deepen suddenly and unexpectedly, with major implications for wind strength as well as other weather elements. Many of the weather events within extratropical cyclones are essentially mesoscale and, on occasions, a single cyclone can be associated with several simultaneous ‘severe’ events such as gales, heavy rain, snow and thunderstorms. This paper describes how the forecaster can add value to numerical model products by using information from a wide variety of sources such as satellite and radar imagery, as well as by monitoring hourly surface observations. Examples are shown in which the forecaster has to make adjustments to model predictions, reconcile conflicting model guidance, and add the all-important mesoscale detail.