Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1209 PM EDT Fri Mar 15 2019 Valid Mar 15/1200 UTC thru Mar 19/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation Including Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Shortwave energy over the northern Plains/Midwest... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z GFS and 00Z ECMWF Confidence: Average In the wake of the exiting deep cyclone over the Midwest and Great Lakes will be an intrusion of northern stream shortwaves from southern Canada which will cross the northern Plains and Midwest through the weekend. The 12Z NAM is a bit sharper with the shortwave impulses and is overall a bit more out of phase with the global models. The 00Z UKMET/CMC solutions also show some evidence of being at least a bit too sharp with energy late in the period dropping down across southern Canada and toward the Upper Midwest. The best model clustering and ensemble support favors the 12Z GFS and 00Z ECMWF, and thus a blend of these solutions will be preferred. ...Weak upper trough/closed low moving into the Southwest... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z NAM and 00Z ECMWF Confidence: Slightly above average A weak upper trough and associated closed low will move into the Southwest through the weekend and should begin to dampen out and shear east toward the southern High Plains by Monday. The 00Z UKMET/CMC solutions are a bit more progressive late in the period in taking the energy across the southern High Plains. The 12Z NAM and 00Z ECMWF are a bit slower and cluster well with the GEFS/ECENS member suites. The 12Z GFS appears to be a bit of a weaker outlier compared to the remaining guidance. So, for now will lean toward a blend of the 12Z NAM and 00Z ECMWF at this time. ...Shortwave over the northern Rockies by Sun... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z GFS and 00Z CMC/ECMWF Confidence: Slightly above average The 12Z NAM and 00Z UKMET are relatively stronger outliers with the shortwave rounding the mean layer ridge along the West Coast on Sunday and dropping down over the northern Rockies. The remaining guidance as per the 12Z GFS, 00Z CMC and 00Z ECMWF is a tad weaker and tends to have better ensemble support, and thus the preference will be toward the weaker consensus. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison