Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1147 PM EST Sat Mar 09 2019 Valid Mar 10/0000 UTC thru Mar 13/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z NAM/GFS Evaluation Including Preliminary Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Positively tilted shortwave trough moving east into Manitoba and Ontario into Monday morning... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z NAM, 00Z GFS, 12Z ECMWF blend Confidence: Slightly above average Only minor timing/depth differences remain with this system, but the 12Z UKMET and 12Z CMC are slower than the strong remaining consensus led by the 00Z NAM, 00Z GFS and 12Z ECMWF which are in agreement with the latest ensemble means, ...Surface low tracking across the Great Lakes today... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model compromise Confidence: Slightly above average Differences with this system are considered small enough such that a general model blend can be used. ...Large closed low forming just offshore of California Sunday night and tracking through Arizona and New Mexico Tuesday/Tuesday night... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS, 12Z ECMWF, 12Z UKMET blend Confidence: Average There is good agreement with this system until Tuesday morning when the 00Z NAM begins to track the center of the closed low south of the remaining model consensus. The 00Z NAM ends up with a slower/farther south evolution of the eventual closed low/negatively tilted trough axis into the Southern Plains. While ensembles had been trending slower over their past few cycles, the past 2 cycles have been consistent and with an upstream kicker, do not think any slower trends will be seen. The 00Z GFS and 12Z ECMWF are a bit faster than the 12Z UKMET but a blend of these three models represents a favored middle ground. Meanwhile, the 12Z CMC is a bit faster than the latest consensus and this is reflected in the latest ensemble guidance. ...Progressive upper trough approaching the Pacific Northwest Tuesday morning... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Average The 12Z CMC is slower with a surface low approaching the coast of British Columbia on Monday, but sensible weather impacts are north of the border. Otherwise, the deterministic and ensemble guidance shows good agreement, with the 12Z CMC toward the faster side of the guidance with the leading edge of mid-level height falls into the northern Rockies by Wednesday morning. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Otto