Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1234 PM EDT Thu Mar 26 2020 Valid Mar 26/1200 UTC thru Mar 30/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Initial Model Evaluation with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Mid-level trough over the Southwest becoming a low as it tracks northeast from Colorado across Central Plains and the Great Lakes Fri night through Sun morning... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z ECMWF/ECENS/06Z GEFS Blend with some 12Z GFS on Day 2 and 12Z NAM on Day 3 Confidence: Average The 00Z UKMET and 00Z CMC are the first to close the low at 500 mb on Day 2 and are thus much slower than the rest of the guidance through Day 3. The 12Z NAM is the last to close the low, so while it is the fastest solution on Day 2, it comes well into the fold on Day 3. The 00Z ECMWF is right within its ensemble mean and is the preferred model solution. The 06Z GEFS mean tracks right along with the EMCWF/ECENS which is a little slower than the 06Z/12Z operational GFS (which has a different model core than the GEFS). The 12Z GFS did slow just a bit compared to the 06Z, so it is able to be used on Day 2 (similar precip pattern to the preference), but remains flatter/farther east with the track on Day 3. ...Shortwave and surface cold front approaching Pacific Northwest Sat and shifting down the California coast through Sun... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 12Z GFS/00Z ECMWF blend Confidence: Average There is good model agreement on the trough shifting southeast off the Pacific Northwest before reaching the CA coast on Day 3. The main differences are with timing and strength of the reinforcing shortwave trough that amplifies the trough down the CA Coast. The 00Z ECMWF is the slowest/most amplified with the reinforcing trough with the position still off the southern CA coast by the end of Day 3 (30/00Z). The rest of the guidance is flatter, more eastward progressive with the 12Z NAM and 00Z CMC the most and the 00Z UKMET not far behind. The QPF among the latest GFS and ECMWF are pretty similar given their similar patterns, so they are preferred 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 Jackson