Probabilistic Convective Storm Guidance for Strategic Planning of Offshore and Transoceanic Flights

The concern for the safety of transoceanic flights has risen as a result of recent airline accidents and incidents – like the Air France flight 447 that was lost over the Inter-Tropical Convergence Zone (ITCZ) en-route from Rio de Janeiro, Brazil to Paris, France on 1 June 2009. In order to mitigate weather-related aviation hazards for offshore and transoceanic flights, the Federal Aviation Administration (FAA) Aviation Weather Research Program (AWRP) has been sponsoring a research and development effort aimed at improving the prediction of oceanic convection for strategic flight planning. The overarching goal of this effort is to create new probabilistic oceanic convection likelihood guidance with a 24-36 hour outlook by utilizing global ensemble model forecasts. The development of this guidance product is closely coordinated with the NWS Aviation Weather Center (AWC) and World Area Forecast Center (WAFC).

This paper presents analyses and initial results toward creating a probabilistic oceanic convection likelihood guidance based on the THORPEX Interactive Grand Global Ensemble (TIGGE) archive. The Total Column Water (TCW) content field from global ensemble models has been used as a proxy for oceanic convection and evaluated against hourly CPC MORPHing (CMORPH) rainfall rate retrievals to better understand model performance in forecasting oceanic convection as a function of storm size, forecast lead time and geographical regions. The evaluation has been performed on a few past accidents/incidents cases as well as one month of TIGGE ensemble forecasts from selected NWP centers. Preliminary results suggest that model performance is dependent on storm type, geographic region, TCW threshold, and NWP center. Additional research is needed to better understand and characterize these dependencies toward developing a viable methodology for creating probabilistic oceanic convection likelihood guidance for offshore and transoceanic flights with a 24-36 hour outlook that could be used to aid aviation weather forecasters in their forecast product development and/or serve as guidance to airline dispatchers for planning transoceanic flights.

This research is supported by the FAA. The views expressed are those of the authors and do not necessarily represent the official policy or position of the FAA.