Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 241 AM EST Sat Feb 02 2019 Valid Feb 02/0000 UTC thru Feb 05/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation...with Final Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 70% 00Z GFS / 30% 00Z NAM blend Confidence: Average ...07Z update... 00Z ECMWF/UKMET/CMC trends were faster with the powerful upper trough crossing the western U.S. on Saturday, and with the downstream surface low impacting the upper Midwest/Great Lakes on Monday, but not to the extent of the 00Z NAM. This makes the 00Z GFS appear more reasonable than the 00Z NAM but having a somewhat faster component still appears warranted with a GFS/NAM blend favored but with more weight on the 00Z GFS. Across the Southeast, minor adjustments were made with the surface low near the Southeast coastline, but a blend of the 00Z NAM/GFS/ECMWF continues to represent a favored average ensemble mean position. ...previous discussion follows... The upper pattern across the lower 48 through Tuesday will remain active across the West Coast with a series of mid-upper level waves to cross the region. Two surface lows will track through the upper Midwest, with the second and stronger low affecting the northern Plains to Great Lakes Sunday night into Monday. Across the Southeast, cyclogenesis will occur along a coastal boundary on Sunday but should track far enough offshore to only have minor impacts for the coastal Carolinas. Across the West with the West with the closed low, minor timing differences show up with the newer 00Z NAM/GFS preferred over the slightly slower 12Z ECMWF/UKMET/CMC given better initialization of the upper low position. Differences across the West with this system are relatively minor at this point given landfall within the next 24 hours. A weak surface low tracking across the upper Mississippi Valley Sunday shows good agreement in the models outside of the 12Z UKMET which does not match the 500 mb vorticity max consensus or surface low consensus shown by the remaining models. A second and more significant surface low for Sunday night/Monday morning shows timing differences between the models with the 00Z NAM fastest, followed by the 00Z GFS, the 12Z ECMWF/UKMET were slower but the 12Z CMC was slowest. The 00Z GFS blended with the faster 00Z NAM appeared best here given the GFS/NAM show better initialization with the ongoing closed low in the eastern Pacific and trends in the ensemble scatter low plots have been generally been quicker despite relatively good agreement. Generally good agreement was observed in the latest deterministic guidance with a weaker shortwave nearing the California coast late Sunday night between the 00Z NAM, 00Z GFS and 12Z ECMWF but the 12Z UKMET/CMC were slower. However, The next closed low to set up near the Pacific Northwest Coast for Monday shows no significant differences between the latest available models. Off of the Southeast coast, individual cycles show minor differences, with the favored ensemble mean surface low positions best represented by a 00Z NAM, 00Z GFS and 12Z ECMWF blend. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Otto