Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1242 AM EDT Fri Apr 12 2019 Valid Apr 12/0000 UTC thru Apr 15/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z NAM/GFS Model Evaluation Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Deep Plains Cyclone through Fri... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General Model Blend Confidence: Above average Both the 00Z NAM/GFS are close with the deep cyclone across the Upper Great Lakes into Ontario, joining the tight clustering among the 12Z solutions and ensemble means. ...Amplifying Long Wave trough over Southwest Fri, with eventual cyclogenesis over Texas Sat... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z ECMWF mean/18Z GEFS mean Confidence: Slightly below average The 00Z NAM and GFS are close handling the short wave energy that tracks from northwest AZ into the base of a developing long wave trough over west TX by 13/12z. While the 00Z NAM is close to the consensus with the surface low over west TX by 13/12z, it becomes a bit faster than the consensus with the low as it moves over the Lower MS Valley. By contrast, the 00Z GFS becomes slower than the consensus with the surface low tracking over the same area. The differences become more pronounced after 14/00z, with the operational models showing more spread with time. The ensemble means, however, form a better consensus with tighter clustering. Because of that, the ECMWF/GFS ensembles means are preferred with this system, especially after 14/00z. Given the spread in the operational models, confidence is slightly below normal. ...Negatively tilted long wave trough moving across the Ohio Valley Sat/Sun... ...Surface low pressure tracking into the Northeast... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-12Z ECMWF blend Confidence: Average As the negatively titled long wave trough tracks from the Mid MS Valley into Ohio Valley after 14/12Z, both the 00Z NAM/GFS are close to a loose consensus with the mid level system by 15/12Z. However, the 12Z ECMWF lags the consensus with the placement of the surface low, further west than even its ensemble mean position. Because of this, the 12Z ECMWF has not included in the preferred blend. Since the consensus with the timing and intensity of the mid level and surface systems is fairly loose, confidence is only average. ...Short waves in a fast mid level flow and associated cold fronts across Pacific Northwest Sat/Sun... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Slightly above average The 00Z NAM/GFS are close to the model consensus with respect to the timing of short waves in the fast mid level flow, though the 00Z GFS becomes faster as a developing long wave trough approaches the Pacific Northwest coast toward 15/12Z. Otherwise, there is some spread concerning the timing of each short wave, which should be expected in a fast flow. Based on this, a general model blend was preferred, but the spread in timing results in only slightly above average confidence. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Hayes