Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1215 AM EDT Mon May 14 2018 Valid May 14/0000 UTC thru May 17/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z GFS/NAM evaluation with preliminary model preferences ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NAM/GFS initialization errors do not seem to degrade their short range forecasts. Merging upper systems across the West/northern Rockies ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-NAM blend; confidence above average While the guidance looks similar aloft, the 00z NAM is more eastward with a low at the leading edge of the initial Great Basin system when compared to the other deterministic and ensemble mean guidance. A compromise of the 12z Canadian, 12z UKMET, 12z ECMWF, and 00z GFS is preferred with above average confidence. Surface low streaking north of US/Canadian border Tue/Wed ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: GFS/NAM/ECMWF blend; Confidence slightly above average The 12z UKMET was the quickest with this system while the 12z Canadian was slowest. Since it is moving through quasi-zonal/quick flow, have ruled out the Canadian. A compromise of the 00z GFS/00z NAM/12z ECMWF is a compromise between the two extremes and makes for a good consensus. Confidence is slightly above average in this choice. Possibly convective deep layer cyclone ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Close to GFS; confidence average The 00z NAM/12z Canadian were the quickest of the guidance while the 12z UKMET took it on a tour of the eastern and central Gulf coast. While the 12z ECMWF looks better convective feedback-wise than its previous couple days of runs, its surface solution is likely too strong, particularly in light of the latest tropical weather outlook from the National Hurricane Center. A solution closest to the 00z GFS is preferred with average confidence. Base of the eastern Canada upper low/trough Stationary front in the northern Mid-Atlantic states Wed ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: GFS/ECMWF/Canadian blend; confidence slightly above average There remains some latitude spread with the front settling into the Mid-Atlantic States with the 00z NAM in two days and the 12z UKMET throughout more northerly with this boundary. Since the guidance is still advertising a 1022-1024 hPa surface high to move through southern Quebec and Atlantic Canada, a placement closer to D.C. is preferred here. A compromise of the 00z GFS, 12z ECMWF, and 12z Canadian is preferred with slightly above average confidence. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Roth