Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1129 AM EST Tue Feb 05 2019 Valid Feb 05/1200 UTC thru Feb 09/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall pattern across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend...through 36 hrs 12Z GFS/00Z UKMET/00Z ECMWF blend...after 36 hrs Confidence: Average The models are in very good agreement overall with the mass fields concerning the initial low-amplitude shortwave that crosses the Midwest and Great Lakes region tonight through Wednesday before then lifting across the Northeast on Thursday. However, gradually the 12Z NAM becomes a bit stronger than the well-clustered global models with the amplitude of energy crossing New England on Thursday which leads to a better developed and stronger surface wave that crosses southern New England. A general model blend will be preferred with this system through Wednesday involving the Midwest and Great Lakes, but then leaning closer to a 12Z GFS/00Z UKMET/00Z ECMWF blend thereafter as the energy reaches the Northeast on Thursday. The 12Z NAM/GFS are close to the multi-model consensus, including the non-NCEP guidance, concerning the track of a closed mid-level low currently over northern CA, as it transitions from a closed low into a longwave trough extending from the Northern Plains down across the Southern Rockies by early Thursday. After that time, the 12Z NAM did trend a bit farther north and closer to the well-clustered 12Z GFS/00Z ECMWF solutions with the associated wave of low pressure, but remains a progressive outlier as it outruns every other global model as its low center crosses the Great Lakes region by late Thursday. The 00Z UKMET supports the GFS/ECMWF camp, with the 00Z CMC a bit more progressive than this camp and also a bit farther south. Stronger ensemble support lies with the GFS/UKMET and ECMWF solutions as a consensus. The next closing mid-level low south of the Gulf of Alaska drops south, reaching a position west of the Northern CA coast by early Friday. The 12Z NAM is displaced a tad south and west of the global model consensus with this system at the end of the period, with the 00Z CMC a little bit farther east. Meanwhile, the models show a northern stream trough digging down across British Columbia and the far Northern Rockies on Friday. The 12Z GFS is seen as being a little slower than the model consensus with the northern stream height falls, with the 12Z NAM and 00Z CMC a touch on the faster side. Accounting for the ensemble guidance, per the 00Z ECENS mean and 06Z GEFS mean, a blend of the GFS/UKMET and ECMWF will be preferred with these height falls approaching the West by the end of the period. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison