Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1250 AM EDT Mon Jul 13 2020 Valid Jul 13/0000 UTC thru Jul 16/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z NAM/GFS Evaluation with Preliminary Preferences/Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Mid-level shortwave troughing over the northeastern quarter of the U.S. Monday to Wednesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Average Trends over the past 24 hours have been faster to exit a mid-level vorticity max/closed low over New England toward the east on Tuesday. The 12Z ECMWF/UKMET are a little slower than the remaining deterministic consensus and the latest ensemble means. Differences are relatively minor and so a general model blend will work fine, but perhaps less weight should be given to the slower 12Z ECMWF/UKMET. ...Longwave trough axis moving through the north-central U.S. through Wednesday .. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/12Z ECMWF/12Z CMC blend Confidence: Average The models show good overall agreement with a broad 500 mb trough and associated surface cold front moving across the central to northern Plains today and Monday night. Some minor timing and amplitude differences continue to be seen, with the 00Z GFS a bit faster with mid-level height falls across the Northern Tier. For the surface front, the 00Z NAM and 00Z GFS were noted to be faster with the progression of the front through the Southern Plains on Tuesday, but the 12Z UKMET was much slower with the 12Z ECMWF/CMC in between the two camps. The faster timing might work out as often the models can be slow to push the cooler air southward through the High Plains, but the faster 00Z NAM progression with a frontal wave through the Midwest on Wednesday is where the 00Z NAM loses out on being preferred. Overall, model differences are small, but leaning on a 00Z GFS, 12Z ECMWF and 12Z CMC blend is considered best at this time. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml This product will terminate August 15, 2020: www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_termination. pdf Otto