Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 136 AM EST Fri Nov 29 2019 Valid Nov 29/0000 UTC thru Dec 02/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Deep closed low crossing the Intermountain West/Plains... ...System reaching the Mid-Atlantic by Monday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-GFS blend...weighted toward 00Z ECMWF/12Z ECENS Confidence: Slightly above average There remain some meaningful model differences with respect to the deep layered closed low currently evolving over central CA. The height falls with this system will translate east across the Intermountain West Friday, and then reorganize and deepen across the High Plains and Midwest on Saturday along with a notably strong surface low. Thereafter, the system advances east across the OH Valley and reaches the Mid-Atlantic region by Monday, with the attendant area of surface low pressure redeveloping along the Mid-Atlantic coast. The 00Z GFS once again tends to be a bit stronger than the remaining suite of deterministic guidance, with the 00Z UKMET seen as being perhaps occasionally a bit too weak. The GFS also tends to track its surface low across the Plains and Midwest a tad south of the multi-model consensus. Although by the end of the period relative the Mid-Atlantic region, the GFS shifts its low evolution farther north. For the time being, the preference will be toward a non-GFS blend weighted toward the 00Z ECMWF/ECENS mean through the period. ...Upper low approaching the West Coast by Sunday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 00Z GFS and 00Z ECMWF Confidence: Average By Sunday, a new closed low will be evolving offshore of the West Coast, including a separate center over the Northwest U.S. which breaks away and pivots offshore the West Coast. There will be some binary interaction between the two centers, with most of the guidance favoring a gradual consolidation of the two systems. The best model clustering at this point resides with the 00Z GFS and 00Z ECMWF, and since these models have rather good ensemble support, a blend of these two solutions will be preferred for the time being. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison