Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 241 PM EDT Fri Jul 10 2020 Valid Jul 10/1200 UTC thru Jul 14/0000 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 12Z Model Evaluation with Preferences/Confidence ...Mid-level shortwave crossing the Great Lakes/Ohio Valley through Sat... ...Associated cold front crossing the Great Lakes... Preference: Blend of the 12z ECMWF/12z GFS/09z SREF Mean Confidence: Average The models differ in the strength of the wave level wave and sfc low crossing the lower Lakes Sat and northern NY/northern New England thereafter. The 12z UKMET becomes and outlier with a significantly stronger low. The 09z SREF Mean/00z ECMWF Ensemble Mean/12z operational ECMWF/12z GFS cluster better in this area, and are preferred. No single model solution looks ideal here, so a blend of the 12z GFS/12z ECMWF/09z SREF Mean is preferred. ...Tropical Storm Fay... Preference: See NHC advisory track Confidence: refer to NHC discussion The 12z UKMET/ECMWF adjusted to a faster track, and are now closer to the 15Z NHC advisory for the track of Fay. Beyond Saturday morning, the models have come into better agreement with most now close to the NHC track in the northeast. The 12z GFS is still a faster outlier once the low departs up into Canada. The 12z ECMWF/12z NAM/12z UKMET are closer to the NHC track positions. ...Mid-level shortwave to cross the northern Plains to Upper MS Valley Sat, Ohio Valley Sunday, Great Lakes to the Appalachians Monday... Preference: Blend of 12z GFS/12z ECMWF/09z SREF Mean Confidence: Average The models indicate an amplifying 700 mb wave crosses from the Northern Plains Sat into the upper MS Valley, continuing into the Ohio Valley Sun. The 12z NAM gets ahead of the pack by a few hours Sun-Sun night, with better clustering timing-wise among the ECMWF/GFS and their respective ensemble means. The 12z UKMET has backed off the prior stronger low on Monday in PA, so the 12z run is closer to the 12z GFS/00z-12z ECMWF. Since the 09z SREF Mean agrees better with the ECMWF/GFS timing/amplitude, with support from the GEFS Mean timing, a blend of these solutions is preferred. ...Longwave trough axis moving into western Canada and the northwestern U.S. on Sun... Preference: Blend of 12z GFS/12z ECMWF Confidence: Slightly above average The models show a broad 500 mb trough and associated sfc front moving across the Pacific Northwest and Northern Rockies Sunday to Sunday Night and Northern Plains Monday. Only minor timing adjustments were noted in the 12Z ECMWF/12z UKMET/12z GFS/12z NAM. Given the minor differences noted with the large scale trough, a general model blend will work well here for the preference. This area has good run to run continuity, so confidence is slightly above average. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml This product will terminate August 15, 2020: https://www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_term ination.pdf Petersen