Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1131 AM EST Sat Feb 01 2020 Valid Feb 01/1200 UTC thru Feb 05/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with Latest Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ ...Trough evolution over the Eastern U.S. through Sunday... ...Deepening coastal low tracking north offshore of New England... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ Preference: General model blend Confidence: Above average The models are in good agreement with the details of the progressive trough moving through the eastern U.S. this weekend. Surface low pressure is still expected to deepen and lift northeast well away from the East Coast through tonight, but the low center will have a direct impact on portions of southeast Canada, and especially the maritimes on Sunday. A general model blend will be preferred. ...Deep longwave trough evolving over the Western U.S.... ...Surface wave activity developing over the lower/mid MS Valley... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of 12Z NAM/00Z CMC/00Z ECMWF and GEFS/ECENS means Confidence: Slightly above average The 12Z GFS again just as it in previous runs continues to be too progressive with the evolution of the deep longwave trough evolution over the Western U.S. over the next few days. The GFS in being more progressive with its height falls also results in the GFS being more out of tolerance with the remaining guidance concerning the developing surface wave activity over the central/southern Plains and especially the lower/mid MS Valley by Monday. The 00Z UKMET does appear to be a bit slow with the trough progression toward the High Plains by the end of the period, but the remaining guidance led by the 12Z NAM, 00Z CMC and 00Z ECMWF, and also the latest GEFS/ECENS means show generally good agreement with the trough timing/depth and surface wave activity. A blend of the non-GFS and non-UKMET guidance will accordingly be preferred. ...Northern stream trough clipping the northern Plains Tuesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The guidance shows a progressive northern stream trough clipping the northern Plains by Tuesday. Mass field spread with this system is minimal, so a general model blend will be preferred. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison