Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 250 AM EDT Wed Jul 08 2020 Valid Jul 08/0000 UTC thru Jul 11/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation with Model Preferences/Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Closed low moving east across south-central Canada through Friday Associated cold front crossing the northern Plains Wednesday/Thursday and the Great Lakes Friday ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z NAM/GFS/ECMWF Confidence: Average A slightly negatively tilted trough axis moving out of the Northern Rockies and beginning to make its way over southern Alberta early this morning will continue to shift east across the Canadian Prairies through Thursday before opening and lifting northeast over northern Ontario on Friday. The 00Z NCEP guidance was a bit faster and the 00Z NAM ended up becoming deeper/slower by Day 2 as the systems makes its way into the northern Plains. The 00Z GFS still slightly outpaces both with trough progression through the Great Lakes Friday/Day 3, but is not too far ahead to be totally discounted, just limited in the blend. Next trough moving into the Pacific Northwest Thursday ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General Model Blend...except non-ECMWF after 12Z Friday Confidence: Slightly above average The 00Z NCEP models remained in good agreement with other models from the 12Z cycle with respect to the depth and progression of this feature into the Pacific Northwest late Thursday. The 00Z ECMWF made a change in that rather than dampening a shortwave as it did over the Great Basin on Friday, it now wants to deepen it as it moves across the Dakotas and dives it into the Upper Midwest by the end of Day 3. Thinking is that there may indeed be some shortwave energy which does that, suspect the ECMWF idea is too strong. Otherwise, no change made to the model preference. Low pressure moving northeast along Eastern Seaboard into this weekend ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 00Z NAM/ECMWF/CMC Confidence: Average A fairly weak cyclone is expected to move drift east-northeast across the Carolinas today before turning northeast up the Eastern Seaboard on Thursday and Friday. At the same time, a mid-level ridge builds to the north of the low across the northern Appalachians and New England. The presence of this ridge continues to suggest a slower solution. The 00Z GFS remained the most progressive guidance with the turn north on Thursday...which was the primary reason that the GFS was not included in the model preference. The 00Z NAM/ECMWF/CMC remained consistent with their previous runs and were favored. Shortwave trough moving across New England Today ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General Model Blend Confidence: Above average Good agreement with this Day 1 shortwave trough crossing northern New England Wednesday. 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 with the 21Z issuance: www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_termination. pdf Bann