Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 115 AM EDT Mon Aug 12 2019 Valid Aug 12/0000 UTC thru Aug 15/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Preliminary Model Evaluation with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 12Z ECMWF/ECENS, 18Z GEFS Confidence: Below Average The synoptic evolution through the forecast period is well agreed upon by the global suite, but small scale features create discrepancies in the sensible weather and synoptic evolution leading to a lower than average confidence forecast. The UKMET continues to be a strong outlier with its ridge on D1, and maintains above consensus heights throughout much of the CONUS through day 3, even as troughing develops in the east. This shunts most of the weather features too far north compared to the global mean. This has been a common trend in the UKMET, and with little support elsewhere is not used in the preferred blend. The 00Z NAM continues to be the furthest north with a shortwave moving across MT/ND/Saskatchewan D1, and is also likely too robust and too far north with QPF along the front sagging into the Mid-Atlantic Tuesday into Wednesday. Although the CMC has a reasonable evolution when compared to the preferred guidance, it is usually a degree or two longitude too far east /fast/ with most of its shortwaves rotating into the amplifying trough across the east. This leaves the GFS and the ECMWF. Both of these deterministic models have similar evolution of the ridge blossoming in the west leading to downstream troughing in the east. However, there remain considerably spatial discrepancies in the QPF fields and frontal/low positions. The ECMWF has been the most consistent and remains the preferred of the deterministic models. With such spread in frontal positions by day 3 as it lags across the Mid-Atlantic, use of the means is suggested to eliminate some of the run to run variability exhibited in the GFS. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Weiss