Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 145 PM EST Mon Feb 03 2020 Valid Feb 03/1200 UTC thru Feb 07/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with Final Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ ...Evolving full latitude trough over the Central US through Thu... ...Surface wave developing over the Lower MS Valley...moving into the interior Mid Atlantic late ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ Preference: 12z NAM/12z ECMWF/12z GEFS mean/00z ECWMF ensemble mean blend Confidence: Average The 12z NAM/GFS are close to the consensus with the evolving positively tilted long wave trough over the Intermountain West through this evening. After that time, the 12z GFS becomes faster than the consensus, as it is not quite as deep with the evolving long wave trough over the Rockies into Central and Southern Plains. This trend continues as the full latitude trough develops over the Central US by 07/00z. The GFS has been consistently faster with this feature over the past several model cycles. By contrast, the 12z NAM remains closer to the consensus through much of the period as the trough evolves. While the 12z ECMWF is close to the consensus through 06/00z, it has sped up its movement of the long wave trough for Day 3 (ending at 07/00z). It is not as fast as the 12z GFS, but it has sped up the trough movement during each of the last three runs. The trend for a faster solution is seen in the 12z GEFS mean as well. The faster solution also makes the 12z UKMET a plausible solution, though it too may still be just a bit fast. The 12z CMC remains the slowest member of the guidance envelope. Based on the above, a blend of the 12z NAM/12z ECMWF/00z ECMWF ensemble mean/12z GEFS mean is preferred. Due to the flux in the timing of the trough as well as some spread in the handling of the surface low across the East Coast, forecast confidence is just average. ...Northern stream energy tracking from British Columbia Tue into the Northern Plains/Great Lakes Thu... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~ Preference: Non-12z GFS blend Confidence: Average Short wave energy in the fast mid level flow tracks from the central British Columbia coast 0at 4/12z into the Northern Plains by 05/12z. During this time frame, both the 12z NAM/GFS are close to the model consensus. After 05/12z, the 12z GFS becomes much more amplified with the trough over the Northern Plains/ Upper MS Valley, closing off over MN/IA by 06/12z. By contrast, the 12z NAM remains close to the tightly clustered consensus, taking the bulk of the short wave energy across the Northern Plains into the Upper Great Lakes by the end of the period. The 12z ECMWF has trended faster with the northern stream short wave, with its timing closer to the 12z GFS. However, the 12z GEFS mean/00z ECMWF ensemble mean support a solution slower than the 12z GFS, so for now, the 12z GFS remains out of the model preference. However, due to the faster 12z ECMWF solution, forecast confidence has dropped to average. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Hayes