Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 155 AM EST Thu Feb 21 2019 Valid Feb 21/0000 UTC thru Feb 24/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation...with Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Overall Pattern Across the CONUS... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend...Northwest/Northeast U.S. 00Z UKMET/ECMWF blend...elsewhere Confidence: Slightly above average The flow pattern across the lower 48 will continue to feature ridging over the Southeast which continues to nose in from the Caribbean and adjacent areas of the southwestern Atlantic, with mean troughing over the West. A shortwave meanwhile that is stretching out from the Upper Midwest through the Great Lakes region will shear across northern New England on Thursday. Elsewhere, a very strong closed low will be evolving over the Southwest Thursday and Friday. This feature will then quickly eject east and then northeast Saturday through early Sunday from the southern Plains to the Great Lakes region. By the end of the period, another shortwave trough and possible closed low will be dropping down the coast of the Pacific Northwest. The models are in good agreement with the details of the shearing trough and associated surface wave activity over the Great Lakes and also coastal areas of New England through Thursday. Regarding the closed low crossing the Southwest, the guidance begins to diverge after 36 hours as the energy ejects out across the southern Plains and ultimately the Midwest and Great Lakes Saturday and Sunday. The 00Z NAM begins to lag the 00Z CMC/UKMET/ECMWF solutions with the height falls and deepening surface low progression. The NAM also appears a bit too far south with the low track over the Plains. The 00Z GEFS mean and 00Z GFS are more out of tolerance across the central Plains with frontal placement Friday and Saturday and also tend to be on the slower side of the guidance and also a bit back to the northwest of the model consensus with the track of the surface and mid level low centers. Although the GFS does tend to come into better alignment with the model consensus at the very end of the period. The UKMET and ECMWF appear to make for a rather strong model cluster overall given at least modest concerns over the NAM and GFS. And also noting that the CMC is probably a bit too far to the southeast with its low/mid level low track toward the end of the period. So, will prefer a UKMET/ECMWF model blend after 36 hours, but prior to this, a general model blend can be used as the energy pivots across the Southwest. Across the Pacific Northwest by early Sunday, there will be another shortwave trough and possible closed low arriving for which the guidance is in rather good agreement mass field wise. A general model blend can be preferred for now with this system. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Orrison