Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1250 AM EDT Thu Jun 18 2020 Valid Jun 18/0000 UTC thru Jun 21/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Eastern U.S. closed low and coastal front ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Slightly above average Closed upper low currently over NC/VA will gradually weaken and lift north/northeast over the next couple of days and slowly evolve into an open wave. There is excellent agreement in the latest model guidance with this evolution both aloft and at the surface, particularly through 48 to 60 hours. Afterward, as the open wave begins to become absorbed into the approaching troughing from the Great Lakes, the GFS shows a faster progression as the wave kicks northeast. It's not enough to toss out as an outlier for now, but less inclusion of the 00Z GFS is supported for day 3 across this region. Closed low developing over northern high plains ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 12Z UKMET/ECMWF/ECENS blend Confidence: Average Shortwave energy over the central/north-central Rockies currently will evolve into a large closed low over southern Canada later Thursday into Thursday night which is then expected to persist through the remainder of the forecast period. Along the southern periphery of that flow, a few impulses move through, one of which passes through the Rockies Friday night into Saturday. Here, the GFS is noticeably deeper, digging the wave further south that any of the other deterministic guidance. The NAM was considered less useful with the closed upper low, as it is too fast to progress it to the northeast compared to the rest of the guidance which shows reasonable agreement through day 3. Given some of the limitations of the GFS and NAM, a UKMET and ECMWF based blend is preferred. Trough approaching the Pacific Northwest by Friday night ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: GFS/ECMWF blend Confidence: Slightly below average Another fast moving shortwave trough will approach the Pacific Northwest early Saturday which is then expected to remain in place through the weekend. The 00Z GFS was a noticeable outlier being way too fast with the initial shortwave energy coming onshore late Friday night and early Saturday. At the surface, low pressure is forecast to brush and skirt the Pac NW and head toward B.C. and here the models differ slightly in storm track and depth. The GFS is to the left/west of the consensus while the ECMWF is to the right. Given some of the timing issues, a blend of the GFS/ECMWF would likely yield a desirable result at this time. Taylor Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml