Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1222 AM EDT Sat Mar 23 2019 Valid Mar 23/0000 UTC thru Mar 26/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z NAM/GFS Evaluation With Preliminary Model Preferences ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Any errors in the NAM/GFS do not seem to degrade their short range/84 hour forecasts. Shortwave moving through the Great Basin/Midwest Sun-Tue ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: GFS/ECMWF/NAM blend, slightly above ave confidence The 12z Canadian/12z UKMET bring this system across the West into the Plains/Midwest as a stronger system than the other guidance. As it is transiting a building mid-level ridge, believe the weaker GFS/ECMWF/NAM consensus makes more sense. This compromise is preferred with slightly above average confidence. Deep layer cyclone lifting into the Midwest Sunday Shortwave moving into the Southeast Monday night ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-12z UKMET blend, above ave confidence Because the 12z Canadian/12z UKMET show greater amplitude to the upstream shortwave moving into the Midwest, they are weaker with this downstream shortwave. As the shortwave is moving under the base of the upper trough set up by the departing deep layer cyclone lifting through eastern Canada, there is reason to believe a stronger solution for this shortwave. Despite this, the 12z Canadian shows a surface low solution at least as strong as GFS/ECMWF/NAM solutions. A non-12z UKMET compromise is preferred with above average confidence. Broad gyre drifting eastward towards the western US Low pressure systems rotating offshore the western US Deep layer cyclone lifting into southeast Canada ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The guidance shows good agreement with these systems, so the preference is for a blend of the 12z ECMWF, 12z UKMET, 00z GFS, 00z NAM, and 12z Canadian with above average confidence. Roth