Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1210 AM EST Sat Jan 25 2020 Valid Jan 25/0000 UTC thru Jan 28/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 00Z Model Evaluation with Preliminary Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Shortwave tracking from the Pacific Northwest to the Mid MS Valley Monday... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend through 48 hours, Non-GFS/CMC day 3 Confidence: Average A shortwave will race across the CONUS to be near the Atlantic Seaboard late in the forecast period. The guidance is in good agreement with this feature racing east then digging southeast from the Northern Plains into the Mid MS Valley and towards the Mid-Atlantic coast Monday. Late Sunday into Monday, the guidance begins to diverge with the speed and intensity of this feature, as the GFS lags considerably the consensus, while the CMC becomes sheared in the pinched flow south of a big upper low over New England. Between the two, the ECMWF/UKMET/NAM are all well within the ensemble envelope, although the NAM intensity is a bit deeper than the remaining guidance. ...Shortwave trough crossing the West Coast Sun...reaching the Southwest Mon... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non GFS/CMC blend Confidence: Slightly above average Feature is relatively well agreed upon moving into the west coast Sunday, and then amplifying into a deeper trough across the Southwest on Monday. The CMC begins to slow to be well west of the global consensus and at the edge of the ensemble envelope by day 3, while the GFS is in good longitudinal agreement, but is a considerably deeper solution. The GEFS/ECENS mean along with the ECMWF/NAM/UKMET are all reasonable as the shortwave evolves into the Southern Plains. ...Closed mid level low tracking from the Mid MS Valley across Ohio Valley Sat into the Northeast Sun... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General Blend through 60 hours, non 12Z/UKMET or 00Z/NAM day 3 Confidence: Slightly above average Very good agreement persists in the evolution of a strong closed low currently across the Ohio Valley lifting northeast slowly through the weekend. The main core of this feature has good model consensus that it will drift into New England by Sunday and then into Southeast Canada Monday. Around the primary low, lobes of vorticity will rotate cyclonically, and while these features are hard to time/distinguish beyond the near term, the NAM is the only true outlier with positioning and intensity of any of these vort maxima. The UKMET Monday begins to drive the upper low a bit too quickly to the east, but only towards 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 Weiss