Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1248 AM EDT Sun Oct 13 2019 Valid Oct 13/0000 UTC thru Oct 16/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Initial Model Evaluation with latest Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Deep Plains/Upper Midwest Cyclone ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average The anomalously deep layer cyclone over the north-central U.S. will gradually weaken as it lifts northeastward across Ontario, Canada over the next couple of days. The initial cold front from this low has reached the East Coast but is forecast to stall across the Southeast on Sunday and going into Monday, and a secondary cold front crosses the Great Lakes and Ohio Valley through Sunday night. The models remain well clustered with this system and therefore a deterministic model blend is preferred. Pacific Northwest to the Northern Plains ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z GFS/12Z ECMWF Confidence: Slightly above average The next feature of interest to affect the western U.S. will be a progressive upper-level trough and associated cold front that should reach the West Coast by early Sunday, and then advance inland across the northern Rockies on Monday. By Monday night, the height falls start arriving across the High Plains and induces lee-side cyclogenesis over the central Plains to Upper Midwest. The GFS and ECMWF global models are fairly aligned with their ensemble means. However, the NAM becomes too amplified over the northern Plains by Tuesday morning and the CMC is farther north with the surface low over the northern Great Lakes by Tuesday night, so a GFS/ECMWF compromise is a good starting point. Southwestern U.S. to southern Plains ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: ECMWF/EC mean/NAM Confidence: Average Troughing moving through the western US will eventually pinch off a southern stream shortwave across southern California early Monday. It remains the case that the UKMET and CMC are more amplified aloft across the Southwest on Monday compared to the other guidance. By Tuesday morning, the GFS and the GEFS mean are more progressive across the western High Plains and the UKMET/CMC are slower. The ECMWF is more amplified at 700mb by Tuesday across the same general area. At the surface, the UKMET is displaced to the north with the surface low over the central Plains. Taking these factors into account, a blend of the ECMWF/EC mean/NAM should suffice for now. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Hamrick