Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 248 PM EDT Tue Mar 10 2020 Valid Mar 10/1200 UTC thru Mar 14/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Closed Low Affecting the Southwest... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: non 12Z UKMET blend Confidence: Slightly above average A closed low offshore of southern California will slowly move eastward into the Southwest with a few mid-level vorticity centers revolving about the common center of the low. Overall trends in the ensembles have been slower with the closed low progression with deterministic model trends a bit mixed. Minor run to run differences with the main vorticity lobes have led to more significant differences with timing of precipitation across the Southwest, but the one model that stands out the greatest is the 12Z UKMET with a slower push toward the east. It appears ensembles have been converging upon an common solution represented by a blend of the non 12Z UKMET guidance. ...Northern stream trough tracking from the northern Rockies, Upper Midwest toward the Northeast through Friday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 12Z GFS/ECMWF/UKMET blend Confidence: Slightly above average A lower amplitude longwave trough will track through the northern CONUS from Wednesday through Friday. At the surface, a cold front will steadily track to the east and south. The 12Z NAM appears too fast with the trough progression while the 12Z CMC too slow given placement of the remaining models and ensemble means in the middle. A blend of the 12Z GFS (slightly faster) with the 12Z ECMWF and 12Z UKMET appears best for this system with confidence slightly above average given the relatively good consistency for guidance in the middle of the two faster/slower extremes. ...Elsewhere across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Slightly above average Elsewhere across the lower 48, a few low amplitude mid-level shortwaves will track eastward in quasi-zonal flow initially in place from the northern High Plains into the Northeast with little difference noted in the latest guidance. In addition, a shortwave will amplify toward the Pacific Northwest on Friday downstream of a highly amplified ridge centered over the Gulf of Alaska. There are minor differences with the latitude of a compact vorticity max located near the coast of Washington/Oregon on Friday, with the 12Z NAM/GFS a little farther north compared to the ____________ Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Otto