Assimilation of lightning data into RUC model convection forecasting

Lightning data have been used experimentally as part of the NOAA Rapid Update Cycle (RUC) assimilation method for improving cloud/hydrometeor/convection initialization. Lightning data can be used to supplement initial information on existence of convection, along with radar and satellite data and a short-range background model forecast. Radar reflectivity data is generally not available over oceanic areas and terrain-blocked areas, regions where lightning data can provide additional information. Lightning data provide conditional convection information: existence of strokes implies that convective clouds are present, but absence of strokes does not imply that convective clouds are not present. This conditional lightning information has been used within the RUC analysis to force convection to become active in the subsequent RUC model. The RUC cloud/hydrometeor analysis combines GOES and METAR cloud data with the previous 1-h RUC forecast, with radar reflectivity and lightning data in an experimental version, allowing intercomparison to ensure consistency between these data types, each with possible error modes. This initial and relatively simple technique for including lightning data will be described at the conference, along with examples of its effect.