Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 239 AM EDT Thu Jul 2 2020 Valid Jul 2/0000 UTC thru Jul 5/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Final Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Eastern U.S. trough ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through Friday, then NAM/GFS/ECMWF Confidence: Moderate The upper low that is currently over New England will gradually evolve into an open trough by Friday night as it slowly moves offshore, and the models are in good agreement on its evolution, thus meriting a general model blend. By Friday night, as a ridge tries to build northeast from the Plains, a trough builds back across northern New England, while a secondary trough develops beneath the ridge axis across the Gulf Coast region. The NAM is stronger with this second trough building in across New England, and the UKMET is much weaker with the trough across the Gulf Coast states since it is much stronger with the building upper level ridge across the Plains and Midwest. A blend of the NAM/GFS/ECMWF depicts a more realistic pattern with better support from the ensemble means. Deep upper trough/closed low across the Pacific Northwest and western Canada ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through Friday, then 00Z CMC/UKMET/ECMWF blend Confidence: Moderate An expansive closed low meandering across Alberta and British Columbia and the Pacific Northwest will linger through Friday as multiple shortwaves rotate around it. The guidance does feature subtle differences in the intensity and position of the individual vorticity centers, but the general mass field shows good agreement through Friday, with the GFS becoming more amplified with the trough reaching the Pacific Northwest coast Friday night. By Saturday, the NAM also becomes stronger with the next impulse to come across the Pacific Northwest. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Hamrick