Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1141 PM EST Thu Dec 26 2019 Valid Dec 27/0000 UTC thru Dec 30/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with preferences/confidence intervals ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Overall Pattern Across the CONUS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: ECENS/ECMWF blend with some GFS/UKMET Confidence: Average Relatively amplified synoptic pattern expected to evolve over the CONUS through the next 3 days. Latest water vapor imagery shows well defined closed low over southern California with another shortwave trough across southern interior Canada. Downstream ridging exists across the southeast and Mid-Atlantic US. The closed low will slowly move eastward and sprawl out over the central U.S. through the weekend with a deepening surface low expected to develop by Saturday morning that then tracks toward MSP by Sunday. The 00Z GFS is on the northern spread of the model spread and a touch deeper on Saturday compared to the rest of the models. The 12Z UKMET however is faster and stronger with the 500/250 mb flow and its surface low is on the eastern periphery of the spread. Compared to the previous cycles, there is tightening of the model solutions with better agreement seen in the ensemble low track spread, particularly by Day 2/3. The ECMWF/ECENS is the most favored consensus approach, but the CMC/UKMET/GFS offer some utility in the day 1/2 period. The 00Z NAM becomes less usable toward Day 3, as its low tracks further to the northwest, wrapped up in the deeper and further north mid/upper level low. The WPC preference is for a blend of the ECMWF/ECENS mean with some components of the GFS/UKMET. For the rest of the CONUS, there is above average agreement, especially across the eastern US where primarily ridging aloft and southerly flow will dominate. Another anomalously strong closed low approaches the Pacific Northwest Sunday/Monday and here there is very good agreement with the mass fields. The 12Z CMC is a touch fast with the approach of the system but overall a general model blend can be used. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor