Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1254 PM EDT Wed Jun 10 2020 Valid Jun 10/1200 UTC thru Jun 14/0000 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 12Z Preliminary Model Evaluation Including Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Shortwave and associated surface low lifting into Canada tonight... ...Deepening eastern CONUS trough and cold front through Friday night... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General Blend through Friday ECENS/GEFS D3 Confidence: Average Through Friday, the global models are in very good agreement in the evolution of a weakening shortwave and associated surface low lifting through the Upper Midwest and into Canada, so a general model blend is reasonable. Late Friday and Saturday, the northeast gets very messy as 4 individual shortwaves interact in some fashion across Southeast Canada. These will likely congeal into a larger closed low/gyre which will then amplify a longwave trough across the eastern CONUS. There is little agreement in the deterministic models into D3 as to how this will evolve, although the ECMWF is a clear strong outlier, while the GFS is by far the most progressive. Without any clear indicator as to which shortwave will become dominant, which would lead to a more definitive evolution of the trough amplification, feel a blend towards the GEFS/ECENS means is most reasonable. This will wash out some of the finer precip details, especially along the Southeast coast where the stalling front could fire convection, but for amplitude and placement of the mean trough prefer to hedge towards the means due to widely varying deterministic solutions at this time. ...Longwave trough off the West Coast and shortwave lifting onshore California by the weekend... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non GFS through D2, Non GFS or CMC D3 Confidence: Slightly Below Average The guidance is becoming at least somewhat better aligned with a subtly more progressive solution into the West Coast. The important shortwave rotating through the base of the longwave trough extending from a closed low off the BC coast will tilt negatively and lift onshore late Friday into Saturday. There remain timing differences of this feature, most notably the GFS continues to be the fastest with the ejection of the shortwave to the northeast. The GEFS mean is also on the fast edge of the ensemble cluster. However, since the other guidance has sped up at least somewhat, using the GEFS mean is reasonable through 60 hours. Thereafter, the CMC becomes a strong outlier with the amplitude of the shortwave as it pivots into the Great Basin Saturday, leaving the ECENS/ECMWF/NAM/UKMET/GEFS as the preferred blend. Weiss Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml