Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1134 AM EST Wed Nov 14 2018 Valid Nov 14/1200 UTC thru Nov 18/0000 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 00Z ECMWF, 00Z UKMET Confidence: Slightly above average In general, the 12Z NAM, 12Z GFS, 00Z ECMWF and 00Z UKMET are fairly closely clustered with a significant proportion of the ensemble members for the overall height patterns across the CONUS in the next few days. The 00Z CMC and its ensemble membership showed more substantial ridging evolving in the West, and more substantial troughing in the East, with many CMC ensemble members outside the primary cluster by Saturday. Therefore, the preference is to lean overall toward a non-CMC blend. However, some important differences with the NAM and GFS will lead to more weight being placed on the ECMWF and UKMET. With respect to the East Coast low, the 12Z GFS continues to be faster and weaker with the developing surface low and associated mid-level wave. There is excellent clustering of ECMWF ensemble members close to the deterministic ECMWF, UKMET and NAM, so greater weight was placed on those models. Ensemble sensitivity analysis shows that the position and intensity of the low off the Northeast coast is most sensitive to the timing of the mid-upper level low in the Mississippi Valley as it begins to eject, and the kicker wave digging into the Great Lakes. In the West, the NAM shows a different configuration of a positively tilted trough digging into the Rockies (slower and a different orientation) relative to all the other models, and given its departure from the ensemble means, the preference was to place less weight on the NAM in the West and later in the forecast period. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Lamers