Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 237 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 12Z 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. However, the 12Z ECMWF did trend toward the UKMET/CMC camp with a bit stronger energy over southern Canada. The latest ensemble means, including the 12Z GEFS mean and 00Z ECENS mean, still do not favor anything quite as sharp as the non-NCEP models. Based on the degree of uncertainty, the preference will be to keep the prior recommendation with a blend of the 12Z GFS and 00Z ECMWF. ...Weak upper trough/closed low moving into the Southwest... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-GFS blend 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 12Z GFS appears to be a bit of a weaker outlier compared to the remaining guidance by the end of the period. A non-GFS blend will now be preferred given that the 12Z CMC/UKMET solutions trended a bit slower and toward the well clustered 12Z NAM/ECMWF solutions. ...Shortwave over the northern Rockies by Sun... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z GFS/CMC/ECMWF Confidence: Slightly above average The 12Z NAM and 12Z 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, 12Z CMC and 12Z 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