Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1239 AM EDT Sat Jun 20 2020 Valid Jun 20/0000 UTC thru Jun 23/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Closed low developing over northern high plains and parade of shortwaves across central Plains ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through day 2; non-NAM blend day 3 Confidence: Average Deterministic guidance remains in good agreement with the closed upper low over Saskatchewan through day 2, however struggles exist with the individual shortwaves that move through the fast zonal flow across the central/northern Plains late in day 2 and on day 3. The first shortwave lifting through the Upper Midwest Saturday is in good agreement across the spectrum of the deterministic guidance. A pair of convectively induced shortwaves is expected late in the period, Sunday/Monday, where there is significant timing and strength differences. The non-NCEP guidance (ECMWF/UKMET/CMC) show a faster/progressive flow with shortwave energy moving through the mid-MS River Valley by the end of the forecast period on d3 while the NAM and to some degree the GFS shows slower movement with the shortwave energy remaining west over KS/NE at the same time. With the expected fast cyclonic flow in place, the faster solutions seen in the non-NCEP guidance is favored at this time. The GFS is also considered as it has trended toward the non-NCEP guidance, leaving a non-NAM blend as the preference this cycle. Troughs approaching the Pacific Northwest through Sunday ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Slightly above average Shortwave troughs will rotate through portions of the Pacific NW and B.C. over the next several days. While depth and timing differences exist across the deterministic guidance, most of these differences are minor such that a general model blend should be sufficient. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor