Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 133 AM EST Sun Nov 17 2019 Valid Nov 17/0000 UTC thru Nov 20/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of 00Z GFS, NAM, ECMWF Confidence: Average ---06Z UPDATE--- No change to the preliminary preference. The 00Z ECMWF did trend faster with the trough approaching the Southwest on Tuesday, and is in better alignment with the GFS and NAM now. ---PREVIOUS DISCUSSION--- Models show reasonable similarity with the overall synoptic pattern over the next few days, although by Monday Night and Tuesday there is a moderate amount of spread. Nevertheless, there is still a fair amount of model agreement on placement of precipitation regions despite the increasing spread. There does not appear to be a systemic bias that would favor one model consistently, and thus an equally weighted model blend is the preference. The 12Z CMC and UKMET were excluded from the preference, however, due to more substantial differences with a digging shortwave over the Midwest on Monday Night and Tuesday. These two models show a much stronger vorticity maximum and a corresponding swath of higher QPF. Additionally, the UKMET continues to show the surface low tracking much further west than any other models in the vicinity of New England in the Day 2-3 time frame. Therefore, the preference is for a blend of the GFS, NAM and ECMWF. The most significant difference (with an impact on QPF) between these remaining models is the timing of the trough approaching the Southwest on Tuesday. The ECMWF is slower, while the GFS is faster, and this is a common bias for these models. A compromise between the timing is preferred. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Lamers