Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1215 PM EDT Tue Jun 26 2018 Valid Jun 26/1200 UTC thru Jun 30/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z model evaluation...including the 12Z NAM/GFS and preliminary preferences ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Western U.S. to the High Plains... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preliminary Preference: Non-NAM blend Confidence: Above average A couple troughs will move from the West to the northern High Plains over the next few days. In general, the guidance is in good agreement with these systems. By the time the second, and larger, of the two upper waves approaches the High Plains on Fri, the NAM becomes slightly faster than the model consensus, quicker to move height falls into the north central U.S. Thus, a non-NAM blend is recommended. ...Eastern U.S... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preliminary Preference: General model blend Confidence: Above average The latest guidance takes the closed low and associated upper trough over the Midwest gradually east and toward the Mid-Atlantic and Northeast by Thursday. The energy will begin to lift out on Friday as a strengthening upper level ridge begins to set up over the OH/TN Valleys and the Gulf Coast states. The NAM and GFS handle this features similarly to the model consensus through 12Z Thu. After that time some relatively minor timing/amplitude differences emerge, but with no clear outliers. Thus, a general model blend remains the preference at this time. ...Possible low pressure offshore the East Coast by Wednesday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preliminary Preference: GFS/00Z ECMWF blend Confidence: Average The 00Z ECMWF and 00Z CMC again support the idea of a more developed area of low pressure by early Wednesday near coastal North Carolina which will then lift northeast and offshore the East Coast ahead of the aforementioned trough moving into the Eastern U.S. The 12Z NAM/GFS have relatively weaker solutions. Given the persistence of both camps of solutions, a compromise is preferred at this time, best represented by a GFS/00Z 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 Ryan