Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1226 PM EDT Fri Oct 19 2018 Valid Oct 19/1200 UTC thru Oct 23/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12z model evaluation...with preliminary preferences and confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12z GFS, 00z ECMWF/UKMET Confidence: Slightly above average The current synoptic setup featured a quasi-rex block over the western US with downstream troughing over the central/eastern US. Over the next 24 hours, a shortwave dropping out of Canada will carve out a deeper trough over the Great Lakes and Northeast US, driving a surface cold front south and east. In its wake, strong Canadian high pressure will reinforce seasonably cool air across the central/eastern US. In general, the 12z GFS/NAM showed little differences in heights through the weekend compared to previous runs and other deterministic models. The GFS (and NAM to some degree) is faster with the shortwave trough progression across the Great Lakes region through Saturday compared to the 00z ECMWF/CMC/UKMET. But it is now more aligned with the 06z GEFS mean. There's very little difference at the surface with the frontal passage through Saturday night. Out West, by early next week a closed low will approach the BC coast where the models exhibit some magnitude and timing differences. The 00z CMC is stronger (closing off 522 at 500 mb) compared to the ECMWF/GFS which is more open, elongated, and slower. With the ridging expected across the Intermountain West, would lean toward a slower progression by that period. The 12z NAM followed its previous run and is the strongest for a lobe of vorticity coming out of Mexico into west central Texas by Saturday evening. The other deterministic models are in good agreement with placement and magnitude there. Overall, a general blend of the 12z GFS with the 00z ECMWF/UKMET is preferred for the CONUS. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor