Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 146 AM EST Wed Jan 23 2019 Valid Jan 23/0000 UTC thru Jan 26/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... Final 00Z Model Evaluation ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Pattern across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS...possibly blended with NAM, ECMWF at times Confidence: Slightly Above Average A storm system will lift through the Great Lakes into Canada. Another wave along the trailing front will affect the Mid-Atlantic states and New England Wed/Thu. This is followed by a period of deep and broad cyclonic flow / troughing blanketing much of the nation, with high pressure generally dominant in the low levels. During the early part of the short range period models are seemingly in strong agreement, the main exception being the NAM which is a few millibars deeper at the surface as the secondary frontal wave moves up through New England toward 25/00Z. This depth issue does have some impact on the precipitation forecast. The NAM is also a bit deep and cold with its thermal fields over the southern Plains on Days 2, 3. Larger scale differences show up mainly out west on Days 2 and 3. A shortwave tops the west coast mean ridge position and then dives south. There is some systematic difference in how the GFS, ECMWF handle this. Viewing spaghetti plots over the past three cycles the ECMWF and its ensemble were faster and less sharp with the wave, taking it to near southwest Texas by 26/12Z, and inducing warmer heights and flattening of the cyclonic flow downstream in the eastern states. The new 00Z ECMWF backed away from this, however, and came into better agreement with the NCEP guidance. The GFS/GEFS and also the NAM have been consistently slower and sharper, digging the wave into Arizona at 26/12Z, and leaving the cyclonic flow intact downstream a while longer. Trends in both the 00Z ECMWF and UKMET support our earlier decision to lean more heavily on the NCEP / GFS solution. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Burke