Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 108 AM EDT Wed Apr 01 2020 Valid Apr 01/0000 UTC thru Apr 04/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z NAM/GFS Evaluation with Preliminary Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Western Atlantic closed low and offshore surface low through Friday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model compromise Confidence: Slightly above average The models show similarly with this system despite some minor placement differences offshore. The 12Z CMC is closest to the coast early this morning but, along with the 00Z NAM through the end of the week. However, a blended approach will work here as the minor differences are all within the relatively tight model spread. ...Mid-level shortwave tracking into Saskatchewan/Manitoba through Thursday morning with associated front into the Northern Plains... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z NAM/12Z ECMWF blend Confidence: Average Minor longitude differences remain with this system through Thursday with the 12Z CMC farthest west and 00Z GFS farthest east. The ensemble means support the middle, best represented by the 00Z NAM and 12Z ECMWF. The 00Z NAM is strongest of the deterministic guidance but a blended approach will temper the 00Z NAM influence given its position looks reasonable. The 12Z UKMET is also considered too far west. ...Mid-level shortwave moving through the Intermountain West, reaching the Northern Plains Thursday night... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z NAM/12Z ECMWF blend Confidence: Average Similar to the above system, the 00Z GFS is farthest east while the 12Z UKMET/CMC are farther west. Ensemble means support a solution closer to the 00Z NAM and 12Z ECMWF which is the middle ground of the latest GEFS and ECMWF means. Concerning the related cold front which extends into the Southern Plains, there is fair agreement among the latest deterministic models with timing. Differences in southward placement should be resolved with a blend of the 00Z NAM, 00Z GFS and 12Z ECMWF. ...Compact mid-level shortwave nearing the coast of northern California Saturday morning... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: non-00Z GFS blend Confidence: Below average Trends in ensemble spaghetti heights have shown some clustering but moderate differences remain. The latest cycle shows better clustering toward the slower solutions, but the faster GFS has been consistent while the UKMET has been trending faster. The slower ECMWF has also been consistent. For now, will go with the greater ensemble support, and away from the quicker 00Z GFS. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Otto