Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1218 AM EDT Fri Aug 16 2019 Valid Aug 16/0000 UTC thru Aug 19/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation...Including Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-NAM blend Confidence: Slightly above average The upper-level pattern starts off with modest ridging across the Southwest and broad northwesterly flow to its north and downstream across the northern Plains and Midwest, leading to broad troughing across the eastern half of the nation. The ridge over the Southwest will continue to weekend on Friday and Saturday as stronger northern stream troughing digs south through southwest to south-central Canada and across the northern Rockies and northern Plains region. On Sunday, the troughing will pivot across the Midwest and Great Lakes region, but will begin to retreat a bit farther north which will allow an elongated subtropical ridge to be focuses across the central and southern U.S. and rather strong zonal flow from the Northwest to the Northeast associated with the westerlies up across the northern tier of the nation. Anomalous moisture will remain in place ahead of a slow moving front which will extend from the Mid-Atlantic region to the Gulf Coast, while impulses in northwest flow aloft keep the central Plains to the Midwest active with multiple rounds of organized convection. There is broad agreement among the global models with the synoptic scale features across these areas, but the 00Z NAM in general appears to be a tad too amplified with its convectively enhanced vort energy crossing areas of the lower MO and middle MS Valleys through Friday and Saturday. Across the Southeast and eastern Gulf Coast region, the guidance continues to hint at a weak area of low pressure developing along the aforementioned front, and the guidance agrees in lifting a weak area of low pressure up along the front and across the southern Mid-Atlantic through Friday night and then offshore the East Coast on Saturday. The height fall evolution across southwest to south-central Canada is better resolved it would appear as compared to 24 hours ago, but the 00Z NAM appears to be a tad too strong with both of its closed lows with one impacting Saskatchewan and Manitoba, and one digging south across British Columbia. There is notably better support from the GEFS mean and ECENS mean for the non-NAM deterministic suite of guidance at this point. Thus, a non-NAM blend will be preferred for now across the CONUS and central and southern areas of Canada. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Orrison