Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 232 PM EDT Sun Jun 03 2018 Valid Jun 03/1200 UTC thru Jun 07/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z model evaluation with final preferences ...Departing upper trough over the Mid-Atlantic coast today... ...Coastal low off of the northern Mid-Atlantic/New England coast through Tuesday morning... Preference: Non-NAM blend Confidence: Average Upper trough across the Mid-Atlantic today is expected to move eastward by tonight, with the associated surface low tracking northeastward off the Mid-Atlantic/Northeast coast. Models handle the upper wave similarly, and the most significant differences are with the track of the surface low off the coast by late Monday. The NAM is on the western side of the spread by 00Z Tue, while the GFS/ECMWF/UKMET/CMC were very close to a relatively tightly clustered ensemble consensus. Thus, a general model blend, excluding the NAM, is the preference. ...Negatively titled upper trough crossing the Great Lakes today with likely closed low over southeastern Canada Tuesday morning... ...Additional surface low developing along the Mid-Atlantic coast by late Tue... Preference: ECMWF Confidence: Average Models handle the trough/upper low similarly through Tue. The 12Z NAM is slightly more amplified than consensus with the trough axis across the Ohio Valley/Appalachians by 00Z Wed and this continues as the trough moves offshore. As another surface low develops across the northern Mid-Atlantic region late Tue, models show a range of solutions primarily with respect to timing as the feature moves northeastward off the coast. The 12Z NAM/UKMET are on the slow side of the spread while the GFS is on the fast side. The 12Z ECMWF was the solution most closely aligned with an ensemble-based consensus, and is the preferred solution at this time. ...Shortwave over the Southwest U.S. today, reaching the Plains on Monday... Preference: ECMWF/CMC blend Confidence: Average Models handle this feature similarly initially as the feature crosses the Four Corners region through tonight. By Mon as the wave reaches the plains, the NAM is the most amplified of the deterministic solutions while the GFS and UKMET make up the least amplified side of the spread. The 00Z ECENS/12Z NAEFS means both support something in between these two extremes, closest to the 12Z ECMWF/CMC, a blend of which is the preference at this time. ...Upper level troughing along the West Coast through Tuesday... Preference: GFS/ECMWF blend Confidence: Average A series of mid/upper-level shortwaves will traverse a broader upper trough, reaching the West Coast starting later today. The evolution of this is a bit complex, with one of the shortwaves quickly crossing the northern Rockies and reaching the northern plains by Wed morning, while energy and a trough axis linger along the West Coast as well. Models generally handle these features similarly through Monday. As the energy ejects east across the northern Rockies/plains Tue-Wed, models show some small timing and amplitude differences, with the NAM seemingly underamplified, and the 12Z GFS/ECMWF showing a similar amplitude but minor timing differences. The GFS/ECMWF also show similar solutions with the trough axis lingering along the West Coast into mid-week. Thus will recommend a blend of these two solutions at this time. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Ryan