Skillful North American Temperature and Precipitation Forecasts for Weeks 3 and 4 Conditioned on the ENSO and MJO Base State

A gap currently exists between official NOAA Climate Prediction Center (CPC) products between the 2-week extended range forecasts and monthly outlooks. Forecasts within this period, covering weeks 3 and 4, are traditionally difficult as sources of forecast skill are unclear due to insufficient time for boundary conditions to take hold while model initialization errors become substantial. CPC is currently exploring filling this gap through issuing experimental outlooks for Weeks 3 and 4 beginning in September 2015.

This work builds upon previous work that developed wintertime North American 2-meter temperature forecasts for Weeks 3 and 4 conditioned on the initial state of the El Niņo-Southern Oscillation (ENSO), Madden-Julian Oscillation (MJO), and linear long-term trend. Although this previous work revealed that substantial regions of North America were able to experience skillful temperature forecasts conditioned on the ENSO and MJO base states during the winter, it remained unknown if such skill would extend to other seasons or to precipitation.

This presentation details forecasts conditioned on the ENSO and MJO base state across 12 running 3-month periods for both 2-meter temperature and precipitation. The results reveal that skill in both forecast variables extends across different combinations of initial states and periods for certain regions. Temperature signals are generally more skillful than those seen for precipitation. Summertime patterns also suggest that the influence of ENSO on North American temperature at leads of 3-4 weeks may be greater than initially thought during this season.