6.2                                   The Forecast Funnel

As alluded to in Section 6.1, the systematic approach to forecasting requires a "top–down" approach in which the forecaster gains an appreciation of the broad–scale features of the atmosphere, then progressively focuses on shorter time and space scales. Snellman (1982) referred to this approach as the forecast funnel. Figure 6.2.1 is adapted from the University Corporation for Atmospheric Research (UCAR), Boulder, Colorado's excellent Cooperative Program for Operational Meteorology, Education and Training (COMET) module on the forecast process (see, for example, http://www.comet.ucar.edu/). The figure schematically shows the process of refining the forecaster's focus from considering the longer atmospheric waves (planetary–hemisphere space scale and weeks/days time scale) through the shorter atmospheric wave length systems such as low–pressure systems/highs (synoptic space scale and days time scale) through the yet smaller systems such as mesocyclones (mesoscale with life span of hours to a day or so), right down to the very local environment of the station or field camp (microscale–virtually what is happening now).

The next three sections will consider aspects of the "forecast funnel" in the Antarctic context. Section 6.3 will illustrate how taking note of the long waves can assist in the forecast process; Section 6.4 will discuss synoptic scale systems and fronts; and Section 6.5 will deal with aspects of the forecasting of mesoscale lows. Many aspects of the microscale are site specific and the reader is referred to Chapter 7 where forecasting aspects peculiar to each station are discussed.