Extratropical cyclones dominate the weather and precipitation in temperate latitudes. The precipitation pattern is often organized in a banded structure. The horizontal scales of the frontal rainbands range from a few kilometers along the cold fronts to several tens of kilometers observed in both the warm and cold sectors of a frontal system. Several theories have been put forward to explain the organization of frontal rainbands; presently the conditional symmetric instability appears capable of explaining several types of rainbands. The most important next stage in the development of this subject is the implementation of conditional symmetric instability in numerical models. Using the mesoscale model of the Pennsylvania State University, Professors Warner and Clark will examine the model characteristics required of a realistic simulation of the rainband structures. The bulk of the rainfall received in temperate latitudes is associated with the passage of either warm or cold fronts. This work, when successfully completed, represents an important step forward in the numerical prediction of mesoscale precipitation.
