Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1258 AM EDT Wed Aug 12 2020 Valid Aug 12/0000 UTC thru Aug 15/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Longwave trough over the Northwest to the Northern Plains through Friday ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: NAM/CMC/ECMWF blend Confidence: Slightly above average A broad upper level trough, in conjunction with a closed low over southwestern Canada, will be in place across the northwestern U.S. through the middle of the week, and then should be in place across the northern Plains by the weekend. This will sustain a cold front tracking from the northern Rockies to the Dakotas. The 00Z GFS becomes faster and more amplified with this trough by 12Z Friday across the Dakotas, and the 12Z UKMET trends stronger by Friday night across the Upper Midwest. Northeastern U.S. upper trough ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: ECMWF/CMC blend Confidence: Average An upper level trough axis gradually builds in across New England and eastern Canada by the end of the week, downstream of a building ridge axis across Ontario and western Quebec. The 00Z NAM is strongest with the trough, and the GFS is slightly east of the model consensus. Blending the ECMWF and CMC would yield a suitable starting point in the process process. Southeastern U.S. upper trough ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model compromise Confidence: Slightly Above Average A weak closed low currently over Missouri will slowly track eastward and evolve into an open trough as it reaches the Ohio Valley and southern Appalachians by this weekend. A general model compromise would work well here. 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 Hamrick