Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1233 AM EDT Sun Apr 12 2020 Valid Apr 12/0000 UTC thru Apr 15/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with Initial Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Southern stream shortwave leading to intense surface low over Great Lakes ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 12Z ECENS mean with some inclusion of the 00Z GFS and 12Z ECMWF Confidence: Average Shortwave energy over the Desert Southwest region currently seen in the latest water vapor imagery will continue to open up as it moves into the south-central Plains over the next 24 hours. Shortwave energy in the northern stream will phase with the southern feature resulting in a powerful cyclone to rapidly deepen from the south-central Plains to lower Great Lakes in the next 36 ours. Guidance has consolidated on a general track and depth with differences tied latitudinally over Michigan where the GFS/UKMET are a southern solution while the ECMWF/CMC/NAM is further northwest at 36 hours. The deterministic ECMWF is displaced well to the northwest from the ECENS mean, while the GFS and GEFS are nearly identical in location from 24 to 36 hours. From a mass field perspective, a blend toward the ECENS mean with some inclusion of the deterministic GFS/ECMWF seems like a favorable approach. Amplifying upper trough over the northern U.S. for early in the week ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend with less weight given to 00Z GFS Confidence: Slightly above average In the wake of the negative tilted shortwave for the eastern U.S. early next week, longwave troughing is expected to develop over much of the northern U.S. for day 2/3. Large gyre over southern Canada pivots toward the northern Great Lakes, where the GFS continues to be a bit too amplified and deep with its 500 mb low but not enough to be discounted completely. Otherwise, the model guidance is reasonable agreement so a general model blend with less weight toward the GFS is preferred. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor