Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1230 AM EDT Sat Jun 30 2018 Valid Jun 30/0000 UTC thru Jul 03/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z NAM/GFS model evaluation...including preferences/confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Mean upper trough advancing from the Intermountain West to the Upper Great Lakes/accompanying cold front... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-21Z SREF model blend Confidence: Slightly above average Broad upper troughing extending from the Upper Intermountain West to the Northern High Plains will continue marching eastward while a system from west Texas punches rapidly northward. 576-dm ensemble spaghetti plots which have shown the disparity between the GEFS/ECMWF ensemble members indicate the solutions have come closer together in the 12Z model cycle. The only true outlier through 01/1200Z is the 21Z SREF mean being decidedly slower. By Sunday evening, the 00Z NAM appears a bit quick to advance the front toward the Great Lakes but does have some company from the 12Z CMC. With most models clustering downstream of the 21Z SREF mean, will reject this solution in favor the others. ...Westward moving mid/upper circulation along the eastern/central Gulf Coast... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 00Z NAM/12Z UKMET Confidence: Average A band of vorticity currently drifting southwestward across Georgia/South Carolina will maintain its push toward the eastern/central Gulf Coasts the next couple of days. A westward track is anticipated under the southern extent of a closed upper high building over the mid-Atlantic. At the surface, most operational solutions indicate a cyclonic circulation accompanying the system although ensemble low plot trends have shown a decrease in the members the past 12 to 24 hours. Timing differences aloft do not really emerge until Day 3 with the 12Z ECMWF on the far western edge and the 21Z SREF mean. The most middle ground solution would be a combination of the 00Z NAM/12Z UKMET which will be the recommendation for now. ...Pronounced upper low taking shape over the Pacific Northwest by early next week... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Through 03/0000Z: General model blend, 03/0000Z-03/1200Z: non-00Z NAM solution Confidence: Slightly above average As the synoptic-scale pattern shifts eastward, amplified flow from the Gulf of Alaska descends upon the Pacific Northwest by early next week. There are minimal differences through 03/0000Z until some divergence in the solutions is noted. Operational models look reasonable compared on ensemble spaghetti spread but the 00Z NAM is east of this pseudo-consensus. Will recommend a non-00Z NAM beyond 03/0000Z. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Rubin-Oster