Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1230 AM EDT Thu Mar 21 2019 Valid Mar 21/0000 UTC thru Mar 24/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation Including Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Trough(s) and Developing Low in the East... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-CMC blend (weight to ECMWF/GFS/UKMET) Confidence: Average Two pieces of mid/upper level energy rotating through the Great Lakes and Mid-Atlantic regions will phase in the next 24-48 hours over the Northeast US, eventually closing off Friday night off the Northeast US coast. A surface low, currently near the SC/NC border, will track up the East Coast, deepening as it moves toward the Gulf of Maine. Mass fields between the various deterministic models are in much better agreement compared to the past few cycles, particularly in the first 24-36 hours. The mid/upper level pattern is fairly similar across the board, while at the surface, there remains a few differences in the track/position. The 12z CMC is further east compared to the model consensus, while the rest of the guidance is nearly identical in track and magnitude. As such, will lean on a non-CMC blend for this system with the heaviest weight given to the ECMWF/GFS/UKMET. ...Remainder of the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Average The strong elongated ridge in place across the Plains will continue early in the forecast period while a slightly negatively titled trough weakens and splits as it moves onshore the west coast. The main energy source will pinch off toward the Southwest US, eventually closing off over Utah by Friday. Through then, model agreement is above average and a general model blend can be used for the mass fields. Some of that energy eventually makes it way toward the central Plains by Saturday where there are some disagreements in timing and location. The ECMWF is further south with the mid/upper low position compared to the CMC which is on the northern edge of the model consensus. The latest (00z) GFS/NAM split the difference but appear to be slightly faster as well. But overall, the differences are not substantial and a general model blend probably would yield a reasonable result for 3 days out. Weak troughing will remain in place across northern California into the Pacific Northwest for the end of the forecast period. There are differences on how strong (south) the trough influence is, but again, model differences are not significant enough to lean/prefer one solution over another. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Taylor