Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1245 AM EDT Thu Jul 02 2020 Valid Jul 02/0000 UTC thru Jul 05/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Initial Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Closed low exiting New England Thursday and back door front diving through late Friday Developing trough near the Gulf Coast Friday ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through Friday, then NAM/GFS/ECMWF Confidence: Moderate Guidance remains in good agreement with little spread in both the spatial and temporal evolution of the closed low dropping southeast away from New England late in the week. By Friday the closed low opens and is well removed from the East Coast, with the CMC a bit faster with the progression of the offshore trough. By Friday night, as a ridge tries to build northeast from the Plains, a trough digs back into New England, while a secondary trough develops beneath the ridge axis across the Gulf Coast region. In New England, a back door front digging southward Friday night into Saturday features similar timing. Across the Gulf Coast, the UKMET is much weaker with the trough as it bulges the ridge too quickly from the west. 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 NAM/UKMET/ECMWF blend Confidence: Moderate An expansive closed low meandering across far western Canada and the Pacific Northwest will linger through Friday as multiple shortwaves rotate around it. This feature is likely to generally lift northeast into southwestern Canada, leaving just a weak trough across the Pacific Northwest by Friday. 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 exception of a faster solution with the 12Z CMC across Washington with the shortwave moving inland. By Saturday, the GFS 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