Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1139 AM EST Thu Jan 16 2020 Valid Jan 16/1200 UTC thru Jan 20/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Central to Eastern US system... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-NAM, non-CMC blend after 18.12z Confidence: Slightly above average Shortwave trough moving into the western U.S. tonight will cross into the Central Plains this weekend. Through 48 hours, the spread seen in the deterministic guidance has lessened with overall above average agreement at 500 mb. The NAM is a tad more amplified with its trough axis as the wave takes on a negative tilt. At the surface, there is still some latitudinal spread with the ECMWF and ECENS members showing a northern/northwest favor compared to the CMCE members further south/southeast. The GFS/GEFS members lie in the middle and probably provide a good approach for beyond 48 hours. The 00Z UKMET is also a good proxy. So, with the NAM being a bit amplified and the CMC too far south/southeast, will lean on a non-CMC, non-NAM blend. ...Pacific Northwest... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Slightly above average The next system poised to affect the Pacific Northwest comes later this weekend as an area of low pressure approaches western Canada. A plume of higher moisture pushes onshore Oregon/Washington. Overall, differences at 500 mb are fairly minor with some of the typical biases seen where the GFS is a touch faster and the CMC is on the slower side of the model spread. At the surface, there is some higher spread and model variability but the majority of the impactful weather pushing into the Pac NW has fairly similar solutions so will continue to suggest a general model blend for this area. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor