87th AMS Annual Meeting

Tuesday, 16 January 2007: 2:45 PM
Subseasonal forecasting with the NCEP Climate Forecasting System in the Western Sahel and tropical Atlantic
214C (Henry B. Gonzalez Convention Center)
Augustin Vintzileos, NOAA/NWS/NCEP/EMC, Camp Springs, VA; and H. L. Pan, W. M. Thiaw, D. Behringer, D. Stokes, and S. Saha
Between weather prediction (forecast at lead times from 0 to 14 days) and seasonal forecasting (forecast at lead times from month 3 and beyond) lies the yet unexplored domain of subseasonal prediction. The difficulty of forecasting at lead times between 15 and 60 days comes from the equal importance of initial conditions for the atmosphere, land surface and ocean. Despite this complexity, it has been shown (Vintzileos and Thiaw, 2006) that forecast of anomalies of cumulative precipitation over the western Sahel area is skillful at lead times between 10 and 35 days. Here, we first review the 2006 monsoon season over the Sahel and describe the ability of the operational CFS to predict the observed deficits and surpluses of precipitation. Waves emerging from the Sahel downstream may show exponential growth upon encountering favorable atmospheric and oceanic conditions. Here, we also explore the forecast skill of the CFS in predicting key oceanic variables at subseasonal lead times that may affect the genesis and the intensity of tropical systems.

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