Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 1245 PM EDT Thu Oct 10 2019 Valid Oct 10/1200 UTC thru Oct 14/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12Z Model Evaluation with latest Preferences and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Deep closed low near the 40N/70W benchmark... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General blend Confidence: Average A deep area of low pressure situated just southeast of the 40N/70W benchmark has generally leveled off in intensity and is forecast to make a slow counter-clockwise loop over the next couple of days before tracking farther out to sea. This storm is blocked by a large low to mid-level high over eastern Canada and part of a Rex block pattern. The 00Z ECMWF and to some extent the 00Z CMC solutions are a bit slower than the model consensus with the cyclonic loop that takes place, and ultimately slower to advance the system east and out to sea. The 12Z NAM/GFS and 00Z UKMET solutions are generally the fastest to do this. The ensemble means per the 00Z ECENS mean and 06Z GEFS mean are supportive of their deterministic counterparts. A compromise between camps will be preferred at this point, and a general model blend should suffice. ...Deep Plains/Upper Midwest Cyclone... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend...led by the 12Z GFS/00Z ECMWF Confidence: Above average A strong deep layer trough and associated closed low over the northern Rockies will be advancing east this afternoon across the High Plains and will continue to deepen tonight through Friday as the system pivots across the upper Midwest. The models are in good agreement overall, but the 00Z ECMWF and 00Z CMC on Friday both tend to cyclonically pivot their strong low centers a bit farther back to the west and northwest across areas of northwest MN versus the 12Z NAM/GFS and 00Z UKMET which keep low pressure a bit farther east by comparison. The ensemble means are split on this as the 00Z ECENS mean supports the ECMWF/CMC cluster, and the 06Z GEFS mean supports the NAM/GFS/UKMET cluster. The 12Z NAM is also seen as being perhaps a bit too strong/deep with its mid-level low center. Meanwhile, a very strong cold front will advance quickly east across the lower/mid-MS Valley and OH/TN Valleys by late Friday, before then reaching the East Coast on Saturday. The 00Z UKMET is seen as being a tad slow with the cold front timing versus the remaining guidance. Regarding the deep closed low over the upper Midwest, a pronounced weakening trend is expected on Saturday as the system becomes vertically stacked. All of the models show good agreement on the weakening trend at this point, and take the system gradually across the upper Great Lakes and into Ontario through Sunday. The preference at this point will be a multi-model consensus led by the 12Z GFS and 00Z ECMWF. ...Western U.S.... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: Non-CMC blend Confidence: Above average A progressive shortwave trough will advance inland from the Pacific Ocean on Sunday and advance into the Great Basin. The models show good timing and depth agreement, but the 00Z CMC appears to be somewhat of a progressive outlier by the end of the period. The remaining deterministic guidance and ensemble means favor going with a non-CMC blend, and that will be the preference. Model trends at www.wpc.noaa.gov/html/model2.html 500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml Orrison