February precipitation totals verification#

Convective precipitation falls out immediately, vertically downwards, as soon as convection is diagnosed (in contrast to hydrometeors classed as large-scale which follow a wind-dependant path down through the atmosphere in the IFS).

The effects of non-advection of showers by the convective scheme:.

Hail is not considered nor developed in the IFS convection scheme, no matter how unstable is the model atmosphere.

Only rain or snow is produced by the precipitation scheme.

Convective precipitation tends to have much greater sub-grid variability than large scale precipitation.

February precipitation totals verification#

Differences of about one order of magnitude are possible although verification that integrates totals over areas that are the same size as the effective grid box size suggests the agreement is generally much better. Localised extreme values in precipitation totals are systematically underestimated in IFS output because of the resolution, and also the related parametrisation of convection.Detail is lost within the grid box due to sub-grid variability, particularly in convective situations when the individual showers might be heavy but the displayed average precipitation is low. Precipitation is the grid box average value, not a point value.Limitations of the portrayal of convective precipitation:.These and other aspects have consequences when forecasting shower activity.

In the current configuration of the convection scheme any showers that are developed are considered to remain within the model grid box column, with precipitation, of whatever type, always falling vertically downwards.