Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1123 AM EST Mon Jan 06 2020 Valid Jan 06/1200 UTC thru Jan 10/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Southern stream trough/low near the TN Valley by Tues... ...Surface low impacting the Mid-Atlantic/Northeast... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Slightly above average A compact, progressive shortwave trough currently pushing into the south-central Plains will race toward the Mid-Atlantic over the next 24 hours. Its surface low moves from the TN Valley to off the Mid-Atlantic by 00Z Wednesday. Overall, model agreement aloft and at the surface show fairly high agreement run to run and within the various deterministic guidance. With that in mind, will side on a general model blend for this area during the next 3 days. ...Parade of Shortwaves Approaching Pacific Northwest This Week... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through 08.12Z; GFS/ECMWF blend thereafter Confidence: Slightly above average Late Tuesday into Wednesday another shortwave trough and front will approach the Pacific Northwest coast. In the large scale sense, the timing/strength appear very agreeable between the various deterministic models. The NAM's earlier slow bias has lessened some with its 12Z run, but still lags the other global guidance somewhat. The 12Z GFS is a bit ahead of the guidance as well. Another fast moving shortwave pushes through the region Thursday within the increasingly more amplified pattern. Timing differences increase with this system with the UKMET/CMC being on the faster side of the model spread and is more amplified with the upstream ridge over the Pacific. The GFS/NAM/ECMWF offer a slightly slower solution, of about the same magnitude/strength, though the GFS is the weakest solution. Will lean on a GFS/ECMWF blend beyond 08.12Z to account for the timing differences seen in the UKMET/CMC. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor