1. 1 Coupled Modeling for Week 3 & 4 Presented By: Suru Saha & Yuejian Zhu (NWS/NCEP)

2. 2 Operational System Attribute(s ) System NameAcronymAreal Coverage Horz Res Cycle Freq Fcst Length (hr) Climate Forecast System (operational, coupled) CFSGlobal110km6hrs45days Global Ensemble Forecast System (experimental, uncoupled) GEFSGlobal34Km/ 52Km 24hrsExtend to 35d SystemAttributes GEFSDA:NCEP hybrid GSI/EnKF; Ini: EnKF (f06) + TS relocation + Centered all perturbed vectors; Model: GFS + STTP CFSDA: 3DVar for atmosphere (CDAS)+ocean (GODAS)+land (GLDAS)+seaice 4 unperturbed members, 12 perturbed members System Data Assimilation or Initialization Technique

3. 3 Why System(s) are Operational?  Primary stakeholders and requirement drivers CPC; Sub-seasonal forecast; Flood/drought monitoring/warning.  What products are the models contributing to? Global products, every 6 hrs out to 45 days (CFS). Key products: weekly mean temperature, precipitation anomaly, global tropical hazards.  What product aspects are you trying to improve with your development plans? Precipitation and temperature MJO skills, TS genesis NH 500hPa height AC, blocking index, HIW pattern Arctic Seaice Prediction  Top 3 System Performance Strengths Skills of forecast MJO index, couple mode of monsoon, ENSO on-set Sub-season variability Anomaly forecast of NA  Top 3 System Performance Challenges Predictability of sub-season variability Connection of MJO and NA weather Interaction of atmosphere-ocean-ice-land-wave-aerosol-ionosphere

4. 4 System Evolution Over the Next 5 Years  Major forcing factors Linkage of weather and climate - seamless forecast system Management decisions within NOAA to satisfy users in agriculture and food security, water, disaster risk reduction and health fall into this range. Improved weather to climate forecasts promise to be of significant social and economic value.  Science and development priorities Build a unified global coupled prediction system (atmosphere-ocean-land-ice- wave-aerosol-ionosphere) Improve model skill for extended range  What are your top challenges to evolving the system(s) to meet stakeholder requirements? Resources to study, understand the impact of all components of the coupled system. Limited predictability, and less forecast skills (less signal compared to noise)  Potential opportunities for simplification going forward Add additional members to the operational CFS runs out to 45 days, from 16 to 80, to increase skill in the week3-6 range. Focus on current GEFS system to couple to ocean and seaice.

5. 5 Top 3 Things You Need From the UMAC 1.How does the ocean impact North American week 3&4 (sub-season) forecast? e.g. what is the meaning of strong MJO forecast index to NA weather? 2.Sub-season (week 3&4) is between weather and climate. What is practical way to extend NWP beyond two weeks? Error is saturated? Any help from model forecast uncertainty? 3.MJO and Predictability? Skill of MJO prediction (in tropics) is around 21 days in the CFSv2. Is there any low frequency system in mid- high-latitude we have found? CFSv2 has 0.6 Anomaly Correlation skill for NAO prediction for week3+4 from Nov-May. However, there is little skill from June-October.