Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 243 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 model evaluation...including final preferences/confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Mean upper trough advancing from the Intermountain West to the Upper Great Lakes/accompanying cold front... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-21Z SREF mean 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 00Z/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: Non-21Z SREF mean model blend 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 have improved considerably after evaluation of all available 00Z guidance. The 00Z ECMWF made an eastward jog relative to its preceding run with all solutions clustering well in the vicinity of southeastern Louisiana by 03/1200Z. The 21Z SREF mean remains an issue here as well being eastward displaced with its QPF shield and more ill-defined aloft. ...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 to ensemble spaghetti spread but the 00Z NAM is east of this pseudo-consensus. Ensemble means stay west of the 00Z NAM which suggests it is somewhat outlying in nature. Will continue the previous preference beyond 03/0000Z favoring a non-00Z NAM solution. 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