Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1136 AM EST Thu Feb 07 2019 Valid Feb 07/1200 UTC thru Feb 11/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Eastern U.S... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above average There is above average model agreement across the eastern U.S. with respect to the deep upper trough/closed low and cold front sweeping east across the Great Lakes, Ohio Valley, Tennessee Valley and Eastern Seaboard going through Friday. Cold high pressure will arrive in the wake of this system through the weekend. A general model blend will be preferred. ...Central/Western U.S... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Blend of the 12Z GFS and 00Z ECMWF Confidence: Slightly above average A pair of closed mid/upper level lows will drop through the western U.S. during the forecast period. The first, currently near 44N/135W, will drop southeast toward the central California coast before weakening and opening up into a progressive shortwave trough across the Intermountain West going through Saturday. There is good agreement among the models with the evolution of this system through this period. However, by Sunday as the energy quickly ejects east across the central Plains and toward the OH Valley, the 12Z NAM ends up hanging on to a somewhat stronger shortwave impulse that is also a bit more progressive than the well-clustered global models. Stronger ensemble support per the GEFS and ECENS suites lies with the non-NAM camp of solutions. Meanwhile, a much stronger closed low is expected to form across British Columbia Friday night which then drops south across Vancouver Island and just offshore western WA early Saturday. Thereafter, the closed low should broaden a bit and shift southeastward and inland across the Pacific Northwest through Sunday as additional shortwave energy digs south down across British Columbia. The 00Z UKMET is most out of tolerance with the closed low crossing the Pacific Northwest and the additional energy over southwest Canada by the end of the period. The 12Z NAM tends to be a tad stronger than the multi-model consensus with the details of this closed low, but is also slower than the 12Z GFS, 00Z CMC and 00Z ECMWF. The CMC though positions its energy a bit north of the GFS/ECMWF camp as the closed low pivots inland. The latest GEFS and ECENS suites of guidance favor the GFS/ECMWF camp overwhelmingly, and thus a blend of the GFS and ECMWF will be preferred overall with the details of the height falls impacting the West and also with lead energy ejecting downstream across the Plains and Midwest through Sunday. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison