A Revised Met Office Icing Potential Algorithm for the World Area Forecast System

To ensure worldwide aviation safety the World Area Forecast System (WAFS) provides global gridded forecasts of major meteorological hazards to aviation including in-flight icing. As a World Area Forecast Centre (WAFC), WAFC London produces forecasts of icing potential on a 1.25 degree global grid.  These forecasts are combined with icing potential forecasts issued by WAFC Washington to produce harmonised forecasts available to the global aviation community.

Recent work at the Met Office has focussed on a way to improve the icing potential so that it is more closely diagnosing the likelihood that meteorological conditions at a given altitude will lead to airframe icing. In addition, this new forecast icing potential diagnostic will have the ability to provide a measure of the severity of the icing.  This new diagnostic has been developed to run from the Met Office global deterministic model which has a horizontal resolution of 17km in the mid latitudes and 70 vertical levels.  Its performance has been assessed using one month of pilot reports (PIREPS) from December 2014.  Further work at the Met Office to produce a satellite icing potential product gives the opportunity to verify this new diagnostic over a longer period of time and these results will be presented.