Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 235 PM EDT Sat Jul 14 2018 Valid Jul 14/1200 UTC thru Jul 18/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Model Analysis for the CONUS... Overall Preference: 12Z ECMWF...Northwest U.S. Blend of the 12Z GFS/ECMWF...remaining CONUS General Confidence: Slightly above average The pattern over the CONUS this weekend will be generally dominated by high pressure aloft and weak flow, with one center over the Four Corners region and another one extending from the OH/TN Valleys south down across the Gulf Coast states. A broad weakness between the two upper level high centers is expected to remain over the central Plains and adjacent areas of the Midwest through Sunday. However, the large scale pattern will change going into early next week as a trough will be digging across the Upper Midwest, Great Lakes and Northeast which will drive a cold front across the Midwest and toward the Eastern Seaboard by Tuesday. The guidance is in good agreement with this scenario, but the 12Z NAM was seen as being a little sharper than the global models with the height falls across the Great Lakes and OH Valley. By Monday and Tuesday, there will be two troughs also impacting the Northwest with one system crossing the Pacific Northwest and the northern Rockies by Tuesday. The 12Z NAM is the strongest with the first system, with the 12Z UKMET the weakest. The 12Z GFS is overall the most progressive. The 12Z CMC/ECMWF solutions more closely match the model consensus. Meanwhile, a second trough will begin to impact the Pacific Northwest by Tuesday evening. The 12Z NAM is the fastest solution with this second system, and the 12Z CMC the slowest. There is very good model timing and depth agreement in general with the 12Z GFS and 12Z ECMWF with this next trough. Based on the latest model clustering and trends, the ECMWF will be the dominant preference across the Northwest U.S. through the period, with a GFS/ECMWF blend elsewhere across the CONUS. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison