National Meteorological Center (U.S.)

"For many years the sea level pressure forecasts from the 7L PE model (and the LFM model) have been computed by the "tendency method". This piece of jargon means that the sea level pressure forecast is formed by adding to the initial analysis of sea level pressure the change in pressure forecast by the model. This is in contrast to the forecasts for all other levels in the atmosphere which are computed by various forms of interpolation directly from the sigma-layer quantities forecast by the model, without reference to the initial analyses. An earlier study (unpublished) of the late 7L PE model indicated that use of the tendency method did help, thus prompting this study of the effects of the tendency method on the spectral and LFM-II models"--First page.

Miscellaneous

United States

National Weather Service (NWS)