Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1134 PM EST Fri Feb 14 2020 Valid Feb 15/0000 UTC thru Feb 18/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Initial Model evaluation with preferences & confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ North-Central U.S. to the Northeast ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend, and less GFS after 60 hours Confidence: Above Average Broad cyclonic flow aloft will exist across the north-central U.S. this weekend after the departure of the strong cold front on Friday. A strong shortwave will cross the Dakotas and Upper Midwest on Saturday and then cross the Great Lakes on Saturday night, but given the paucity of moisture available, this should not be an impactful event. There is very little ensemble spread and the deterministic models are in very good agreement overall. The GFS gets slightly more amplified by early morning across southern Canada with the next shortwave perturbation to pivot around the larger parent low that is well to the north. There is similar agreement on the timing of the cold frontal passage. Trough building in across the Western U.S. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/12Z ECMWF/12Z EC mean Confidence: Slightly above average Zonal flow that will initially be over the West Coast region is forecast to become more amplified by Sunday night as a shortwave trough tracks southeastward from the Gulf of Alaska. This will resulting in height falls across much of the western U.S. to begin the week. Differences with the 00Z NAM become apparent as early as 36 hours into the forecast period with a greater degree of amplification over British Columbia, and this becomes more apparent with the northern stream component over the northern Plains by Monday night. This in turns induces a stronger surface low over the Upper Midwest that has little support from the remaining guidance. The 12Z UKMET is also a little stronger with the southern stream component of the trough beyond 60 hours. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Hamrick