Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1129 PM EST Sat Feb 01 2020 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 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. through the remainder of the weekend. As the trough becomes negatively tilted off the coast, a surface low pressure will deepen and lift northeast well offshore, eventually impacting portions of southeast Canada, especially the maritime on Sunday. A general model blend is 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 CMC/ECMWF and 12Z GEFS/ECENS means Confidence: Slightly above average The 00Z NAM/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. Interestingly enough, the quick progression of the longwave trough, as shown by the NAM/GFS, allows phasing to occur with northern stream trough resulting in cooler thermals and also a sharper northern axis to the QPF. Conversely, the 12Z UKMET appears too slow with the trough progression toward the High Plains by the end of the period. The remaining guidance led by the 12Z CMC/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/UKMET/NAM is preferred. ...Northern stream trough clipping the northern Plains Tuesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z CMC/ECMWF and 12Z ECENS Confidence: Above average There are subtle differences with respect to a northern stream trough clipping the northern Plains into the Great Lakes region by early Wednesday. The 12Z UKMET is too progressive while the 00Z GFS/NAM are too amplified and a tad slower allowing this piece of energy to phase with the longwave trough to the south and west. This results in differences in the thermals and QPF, especially Tuesday into Wednesday. It appears, based on continuity and the overall speed of this trough, that a flatter trough axis advancing east would seem most reasonable. Therefore, a blend of the 12Z CMC/EC and ECENS is preferred.. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Pagano