Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 145 PM 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/UKMET/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/UKMET/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 a consensus of the 12Z GFS/ECMWF/UKMET 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 latest ECMWF run did periodically trend a little slower than the very well-clustered GFS/UKMET camp, but it is well within the ensemble spread of the 12Z GEFS and 00Z ECENS suites. The 12Z CMC a bit more progressive than this camp, but not as fast as the NAM. 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 12Z CMC/UKMET/ECMWF solutions all a little farther east and also east of the 12Z GFS. Overall, there is better ensemble support for the camp of solutions that are farther east and approaching northern CA by the end of the period. Meanwhile, the models show a northern stream trough digging down across British Columbia and the far Northern Rockies on Friday. The 12Z GFS/CMC solutions are seen as being a little slower than the model consensus, with the 12Z NAM a touch on the faster side. The 12Z UKMET/ECMWF solutions are well-clustered in between the slower and faster camps. Accounting for the ensemble guidance, per the 00Z ECENS mean and 12Z 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