Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1130 PM EST Wed Nov 27 2019 Valid Nov 28/0000 UTC thru Dec 01/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Strong upper low over the Northeast... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average Model spread is minimal with the strong upper low crossing into the Northeast. This system will quickly move offshore by late Thursday. A general model blend will be preferred with this system. ...Deep closed low crossing the Intermountain West/Plains... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 00Z NAM and 12Z ECMWF Confidence: Slightly above average Some of the biggest model differences relate to the deep layered closed low currently near the CA/OR border. 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. The 00Z GFS by 36 hours edges stronger than any other piece of guidance while traversing the West, and becomes a deep outlier by Saturday across the Plains. Meanwhile, the 12Z UKMET is overall the weakest solution through the period. The 12Z CMC is actually relatively weak as well compared to the multi-model consensus and the ensemble suites per the GEFS and ECENS. Overall, as the system crosses the Plains and aims for the Midwest, the 00Z NAM and 12Z ECMWF appear to have some of the better clustering and support from the GEFS mean and ECENS mean. And so a blend of these two solutions will be preferred with this specific closed low. ...Upper low approaching the West Coast by Sunday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 00Z GFS and 12Z ECMWF Confidence: Average By the end of the period, a new closed low will be evolving offshore of the West Coast along with low pressure at the surface. The 12Z CMC appears to be a weaker outlier with this system. The 12Z UKMET overall may be a bit too slow to advance the system toward the West Coast. The best model clustering with this system tends to reside with the 00Z GFS and 12Z ECMWF, and so a blend of these solution will be preferred which is also reasonably well supported by the latest GEFS mean and ECENS mean. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison