Background

• Since August, in response to poor NAM performance, EMC has run two separate parallels testing upgrades

• Poor performance includes

  • Overdevelopment of mid-latitude cyclones
  • Exaggerated “digging” too far south
  • Convection (deep & shallow) triggering issues

• Parallel runs are:

  • In data assimilation: new divergence damper with extra damping of the external mode, applied (5x) more heavily in NDAS to reduce noise
  • Tuning convection and microphysics

• Two parallel runs were combined for final testing beginning 2 November

• Codes (after speeding them up) turned over to NCO on 27 November