Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1153 PM EST Sun Feb 02 2020 Valid Feb 03/0000 UTC thru Feb 06/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with Latest Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ ...Deep longwave trough evolving over the Western U.S. this week... ...Surface wave activity developing over the lower/mid MS Valley... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ Preference: Blend of the 12Z UKMET/ECMWF, 18Z GEFS mean, and 00Z NAM Confidence: Slightly above average Shortwave trough coming onshore the western US currently is expected to drop southeast toward the Four Corners over the next 24 hours. The 00Z GFS continues to be very progressive with the trough as it ejects into the south-central Plains in the Day 2/3 time frame. Looking at the 18Z GEFS, the operational GFS is faster than any of the ensemble means, and the GEFS mean is reasonably close to the operational UKMET/ECMWF. So while the deterministic GFS is an outlier, there is some utility in the GEFS mean. The 00Z NAM trended somewhat slower and now lines up more similarly to the ECMWF/UKMET and now has some utility and can be incorporated (at least from a mass field perspective). Finally, the CMC remains a slower/deeper solution with its 500 mb heights digging way to the south/southwest (and overall slower progression). With all in this mind, will lean toward a ECMWF/UKMET blend with some inclusion of the 18Z GEFS mean and 00Z NAM. ...Northern stream energy traversing the northern Plains/Great Lakes... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ Preference: non-GFS blend Confidence: Slightly above average Northern stream troughing is expected to clip parts of the northern Plains, Great Lakes, and northern New England through Wednesday. Overall, the guidance shows fairly good agreement with the differences more subtle than large scale. Toward the end of the forecast period, the 00Z GFS lies ahead of the rest of the guidance. The non-NCEP models generally have better support from the GEFS/ECENS means with this energy, and overall with the lead energy outside of the UKMET. So, with the GFS camp relatively out of tolerance, the preference will be toward a blend of the 12Z ECMWF/GEFS mean and 12Z ECENS mean with the northern stream energy going through midweek. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor