Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1258 AM EDT Fri Mar 20 2020 Valid Mar 20/0000 UTC thru Mar 23/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00z Model Evaluation with Latest Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Low pressure and cold front crossing the Upper Great Lakes and Northeast... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Slightly above average The models are in good enough agreement with this system to merit a multi-model blend as a starting point in the forecast process. ...Mid level troughs affecting the Northern Plains into the Upper Great Lakes... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/12Z ECMWF Confidence: Average For the first short wave tracking out of central Manitoba, the 00Z NAM is still a little stronger than the other guidance as it reaches North Dakota midday Saturday, and the 00Z UKMET has trended closer to the consensus with regard to timing. For the second short wave tracking from Alberta into the Northern Plains by Sunday morning, the 00Z NAM is more amplified with the wave and the CMC and UKMET are slightly delayed. A blend of the GFS/ECMWF should serve well as a starting point in the forecast. ...Mid level trough crossing the Southwest Saturday... ...Closed mid level low approaching Central/Southern CA Sun... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/12Z ECMWF Confidence: Average Short wave energy originating near 32N 133W at 20/12z tracks toward the Southern CA coast, reaching far Southern CA/northern Baja Peninsula at 21/12z. The 00Z UKMET is not as slow as earlier runs, but still slightly slower. For this feature, a blend of the 00Z GFS/12Z ECMWF is preferred. A closed mid level low near 34N 135W at 21/12z wobbles toward the Central and Southern CA coast by the end of the period (23/00z). With this feature, the ECMWF and its mean are slightly slower than the other guidance by Sunday night, and the GFS is closer to the consensus timing compared to earlier runs. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Hamrick