Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 230 PM EDT Mon Jun 08 2020 Valid Jun 08/1200 UTC thru Jun 12/0000 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 12Z Model Evaluation Including Final Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Positively tilted trough over the Intermountain West that spins off a low that crosses the central Rockies Monday night and lifts over the Upper Midwest Wednesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: non-NAM blend Confidence: Average Differences begin to develop by early Tuesday as both the northern and southern stream portions of the trough move east of the Rockies into the northern and central High Plains. The NAM shows a less amplified and more progressive northern stream trough moving across the northern Plains on Tuesday, which in turn helps to allow the developing southern stream low to linger over the central Plains longer than the model consensus. By late Tuesday and continuing through Wednesday, the NAM is a notably slow outlier as the system moves across the central Plains and mid Mississippi valley. In the northern stream, the GFS become a relative outlier, with a more amplified trough/closed low developing over the upper Midwest on Wednesday. With respect to the timing of the associated front drifting east across the northern Plains and upper, timing differences are minor through late Tuesday before the NAM begins to move east of the consensus. ...Cristobal... ~~~~~~~~~~~~~~~~~~ Preference: ECMWF Confidence: Average Models are in good agreement into early Tuesday, with increasing spread late Tuesday into early Wednesday. With its more progressive upstream trough (described above), the NAM track moves east of the model consensus as the system moves into the upper Great Lakes Tuesday night into Wednesday morning. By Tuesday night, as the system begins to interact with its more amplified upstream trough, the GFS moves to the west side of the guidance. As the system moves across the upper Great Lakes Tuesday morning, the ECMWF has offered a consistent compromise between the GFS and NAM positions. ...Southern Gulf of Alaska Low Stalling off the BC Coast Tuesday night through Wednesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General Model Blend Confidence: Above Average Overall, models are good agreement -- with no significant outliers through early Thursday. Pereira Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml