Earth System Prediction Capability Demonstration Goal #1 – Improved 1-6 Week Forecasting of Extreme Weather Related to Blocking Events – Initial Directions

The Earth System Prediction Capability (ESPC) multi-agency program is in its very early stages, but in this paper, we will present some initial ideas on one important demonstration envisioned for ESPC.

The ultimate goal of this ESPC demonstration (labeled ESPC Demo #1) is improve 1-6+ week forecasts of blocking and stationary waves with related prolonged weather conditions (heat or cold, excessive precipitation or drought, etc.). Such events are related to multi-day to multi-week power load anomalies, anomalies in renewable power generation, and in some cases, interruption of transmission.

We will apply our current understanding of the blocking process to the assessment of current generation of forecast systems and developing diagnostic tools applicable to both the initial (analyzed or reanalyzed) and model predicted states. Activities will likely include diagnosing longer-term weather anomalies from atmospheric blocking (defined here as ridge or trough quasi-stationary events with duration of at least 4 days to 2+ months), predicting seasonal statistics at various lead times up to six months, predicting individual events (onset/ persistence, structure/ cessation), and predicting outcomes (floods, droughts, fires, extreme temperatures, snow/ice departures from climatology).

An important component of ESPC Demo #1 activities is to evaluate these blocking events using the current NOAA Climate Forecast System (CFS), along with experimental atmospheric-ocean coupled models including FIM-iHYCOM, National Multi-Model Ensemble (NMME) coupled models (from NOAA/GFDL, IRI, NCAR, and NASA/GMAO, all applied along with CFS to seasonal forecasting), and DOE and Navy lab models, as applicable. Evaluation of these ESPC-related models will require, as with NMME models, involvement of the seasonal forecast user community including the energy community.

There are several possible causes postulated for onset and cessation, each with their own sources of predictability and technical approach [seems like a confusion of categories (physical processes and research tactics) here] including Madden-Julian Oscillation (MJO) interaction, extratropical (ET) wave configurations, tropical cyclones (TCs) with strong extratropical transition (Northern Hemisphere fall), Sudden Stratospheric Warming (SSW) events, and early season snow cover or melting. Ultimately, the ESPC Demonstration #1 must evaluate predictability of these possible sources of blocking using next-generation coupled atmospheric-ocean models.