Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 318 AM EDT Mon Jun 22 2020 Valid Jun 22/0000 UTC thru Jun 25/1200 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Closed low over Manitoba/Ontario Shortwaves crossing the Plains ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Day 1: general model blend Day 2: non-GFS Day 3: ECMWF/UKMET Confidence: Average Large closed upper level low over Manitoba will settle over the northern Great Lakes by the end of the period with several shortwave troughs and convective complexes expected over the Plains. The models show fairly good agreement with the large scale upper level pattern but differ somewhat with the surface fronts and associated low positions for day 2/3, where the GFS is to the south and slower with its low position during day 2 and by day 3, the UKMET/ECMWF becomes more favored as the NAM/GFS show higher spread compared to the model consensus. Troughs approaching British Columbia and Pacific Northwest ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Average 07Z update: The 00Z ECMWF trended much more favorably and toward the GFS/UKMET solutions with a more ampoflied shortwave trough moving through the region on day 3. Although it remains the faster solution, the spread is significantly less and fits the expected pattern better, so the model blend preference was updated to include a general model blend of the available deterministic guidance. ---previous discussion--- A pair of shortwave troughs will approach the Pacific Northwest over the next couple of days, the first impacting mainly British Columbia Monday. A second, stronger shortwave trough digs across the Pacific Northwest mid-week where the are some model differences. The 21.12Z ECMWF is faster and flatter with its upper level wave across the northern Rockies in the 60-84 hour range, which seems a bit of an outlier compared to the est of the guidance and the ensemble means. The 21.00Z ECMWF showed more similarity to the GFS/UKMET/CMC models, so it could be considered more useful. The incoming 00Z guidance will show whether the 12Z ECMWF is a true outlier or the beginning of a trend, but for now will lean on a non-ECMWF blend. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor