Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 236 AM EDT Tue Oct 08 2019 Valid Oct 08/0000 UTC thru Oct 11/1200 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with Preferences and Forecast Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Energy amplifying over Central Appalachians/Mid-Atlantic... ...Deepening surface low pressure off the East Coast... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: 12z ECMWF/CMC blend Confidence: Average 07z update: The 00z ECMWF and CMC trended away from the stronger and NW and N solutions of the 12z runs and centering closer to the initial preference of the 12z ECENS and closer to the weaker GFS. The 00z UKMET was a bit slower to the occlusion phase, and now has skipped past to the fastest guidance member being very strong and furthest northwest in the New York Bight; similar to the less favored 12z ECMWF solution. Given better overall agreement toward the ECENS mean and the center of the total ensemble suite, will support a 12z ECMWF/CMC blend at average confidence. ---Prior Discussion--- Now that the tropical shortwave has rounded the western edge of the subtropical ridge and is within the larger developing warm conveyor belt, the overall guidance suite is starting to consolidate on a solution. The lingering shortwave energy in the central Appalachians is starting to also come into better overall agreement evolving into a weak Rex formation. The uncertainty remains in the depth of the cyclogenesis and how far the wobble of the occluded low will press toward the Hudson Canyon/New York Bight region. The 12z ECMWF has once again flopped to the opposite side of ensemble solutions with a very strong/deep solution with the ECENS mean/bulk of ECENS members a bit weaker and further southeast; though not to a dramatic difference. The ECMWF is joined by the even deeper 00z NAM (typical of the day 3 over-deepening bias) as well as a slight westward shift of the 12z UKMET. These solutions appear to have the greatest deep convection/latent heat influence and given the strength of the tropical plume/moisture feed, there is growing confidence toward this evolution. The 00z GFS has shifted north and west with slightly stronger solution than the 12z/18z runs and well west of the 12z/18z GEFS members, but also remains the weakest with the most subtle of wobbles of the surface low after occlusion. The CMC continues to show the greatest run to run consistency but is also a bit further north and is a compromised of the UKMET/NAM/ECWMF and GFS clusters. Overall, the clustering as reduced sufficiently to favor a general model blend with greatest weighting toward the most central members (ECENS mean/UKMET). Confidence is increasing but given the smaller but very impactful differences confidence is only average in this UKMET/ECENS mean weighted general model blend preference. ...Deep upper trough/closed low amplifying over the West... ...High Plains cyclogenesis... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend After 11.00z: Lower weight in the 00z GFS Confidence: Above average 07z update: The 00z ECMWF trended faster closer to the initial preference through 84hrs. The CMC and UKMET both trended favorably toward tighter overall agreement. As such, this leaves the GFS a smidge off in the mid to upper level mass fields enough to reduce weighting after 11.00z but a general model blend can be employees with Above average confidence. ---Prior Discussion--- Models continue to show very strong agreement with the evolution of the deep latitude, positive tilt trof through about 10.00z. It is at this point, there is increased shearing between the closed low lifting away in continental Nunavut and the amplifying base of the trof across the terrain in the Central Rockies. The 12z/18z GFS were both very fast being weaker/elongated in the High Plains, which did not appear right given the vertical vorticity stretching expected...as such the 12z/18z GEFS were much slower. The good news, is the 00z GFS has slowed due to a more compact evolution to the deepening low into the Central Plains. This dramatically slowed the frontal zone/convective clustering across OK/NE TX even more than the UKMET/CMC, even though the 5H closed low remains a bit too fast (so a bit more vertically stacked earlier). This is opposed by the 12z ECMWF which typical of any potential negative bias, would be being too slow; though this bias is best noted when the operational is much slower/deeper than the ECENS mean, which is not the case today particularly after 72hrs. However, with stronger overall agreement in the NAM, UKMET, CMC and the slowing of the GFS...it is harder to have confidence in higher weighting in the blend. So WPC preference is a general model blend with above average confidence before 72hrs. After 72hrs (11.00z), WPC preference would be to still be a general model blend but lower weighting to the operational ECMWF and GFS. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Gallina