Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1236 PM EDT Tue Jun 16 2020 Valid Jun 16/1200 UTC thru Jun 20/0000 UTC ...See NOUS42 KWNO (ADMSDM) for the status of the upper air ingest... 12Z Model Evaluation Including Initial Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Southeast U.S. closed low and coastal front ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: High The cut-off upper low that is currently parked over South Carolina is expected to remain nearly stationary through Wednesday evening before gradually lifting north and eventually becoming absorbed by the westerlies by the weekend. This is supporting a surface low near eastern North Carolina that is fueling convection and heavy rain for portions of the Southeast and Mid-Atlantic region. The models are indicating very good synoptic scale agreement on the progress of the upper level system. At the surface, the 12Z NAM is slightly weaker with the low, but still within the realm of possibilities. Therefore, a general model blend with high confidence can be recommended. Closed low moving into the Northwest Tuesday into the Northern High Plains by Thursday ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through 00Z Friday, then 12Z NAM/00Z UKMET/00Z ECMWF blend Confidence: Moderate The upper level low over Washington and Oregon Tuesday morning is forecast to cross the northern Rockies and become absorbed by a second evolving upper low over south-central Canada by Thursday. This will sustain an occluded surface low and a slow moving cold front across the Dakotas through the middle of the week. The two main differences noted in the guidance is a stronger system with the 12Z GFS across Saskatchewan and Manitoba, and the CMC becomes displaced to the south by 00Z Friday, and therefore its surface low is farther south near the U.S./Canadian border compared to the other guidance. Therefore a blend of the 12Z NAM/00Z ECMWF/UKMET should suffice as a starting point in the forecast process. Hamrick Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml