Ingredient Maps with Frontogenesis and PVF



(click to enlarge)

A second set of ingredients maps (see example above), is being generated twice daily for the 0Z and 12Z ETA model (see midwestern PVF, eastern PVF, or western PVF on the ETA Ingredients page). simultaneously with the first. These include QG (Q-vector, white contours top left) and non-QG (frontogenesis, white contours top right) forcing diagnostics, as well as PVQ (green, bottom left) and a new parameter, PVF (blue bottom right). PVF is the frontogenesis analog to PVQ: it is the product of frontogenesis and PVes, where PVes is negative and frontogenesis is positive. Thus, it highlights areas where there is frontogenetic forcing for ascent in the presence of instability. See the discussion of PVQ for more information.

In addition, these maps show the distribution of PVes in the top right and left panels and the relative humidity and mixing ratio in the bottom right and left panels. The moisture information will aid in determining whether an area of forcing, with or without instability, coincides with sufficient moisture to generate some precipitation.

As with the traditional ingredients maps, these new maps are generated for three levels/layers: 850-800mb, 750-700mb, and 650-600mb (plus 550-500mb for the western area). A shallow moist layer will significantly reduce the precipitation generated by any response to a given forcing/instability combination.