Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 301 PM EDT Sun Mar 08 2020 Valid Mar 08/1200 UTC thru Mar 12/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of 12Z GFS, 12Z ECMWF, 00Z ECENS Confidence: Slightly above average ---19Z UPDATE--- No change to the preliminary preference. The 12Z ECMWF is fairly consistent with its prior run and the 12Z GFS. The UKMET and CMC remain slower for the closed low approaching the West Coast. ---PREVIOUS DISCUSSION--- The most noteworthy trend with the arrival of the 12Z GFS and NAM is that the GFS has slowed down the progression of the closed low approaching the West Coast. It is now more similar to the 00Z ECMWF and ECMWF Ensemble Mean (and the previous preference). The 00Z UKMET and 00Z CMC are slower and have an extension of a low-mid level jet further inland over the Great Basin. This leads to notable differences in precipitation patterns by Tuesday. Meanwhile, the 12Z NAM is now faster than most other guidance with the closed low. The preference is to lean toward a blend of the 12Z GFS and 00Z ECMWF, which is much closer to the ensemble means. This preference applies elsewhere in the country. With model differences are not quite as drastic for other systems and regions, a blend of the 12Z GFS, 00Z ECMWF and 00Z ECMWF Ensemble Mean should be relatively similar to a general model blend. Rainfall placement in the Ozarks region on Day 3 is the subject of some disagreement, but there is greater uncertainty as this seems to be related to convective processes on the northern periphery of a pool of instability. Therefore, convective mode should play a larger role in the eventual character of the QPF swath across the region. For now, the 00Z ECMWF and 00Z ECMWF Ensemble Mean seem to offer a reasonable placement close to the northern instability gradient on most models. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Lamers