Model Diagnostic Discussion NWS Weather Prediction Center College Park MD 144 PM EST Sat Jan 19 2019 Valid Jan 19/1200 UTC thru Jan 23/0000 UTC ...See NOUS42 KWNO (ADMNFD) for the status of the upper air ingest... 12z Model Evaluation Including Preference and Confidence ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...Eastern U.S... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend Confidence: Above Average 19z update: A slight deepening was noted in the 12z ECMWF, but placement, timing, etc remain solid enough to keep with the initial general model blend preference at above average. ---Prior Discussion--- Phasing streams along the East Coast blossom into a deep cyclone over New England by Monday, with help from a fast moving clipper shearing through the northwest flow and kicking the southern stream energy along the eastern side of the strong cyclone. The model guidance continues to be very strongly aligned given the strength of the system. While there are some internal timing/placement to the surface wave in the Gulf of Maine, cannot see an solid reason to not support a general model blend at above average confidence; even the low level thermal fields are fairly tight (though NAM/CMC do show some very slight typical colder bias). ...Western/Central U.S... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Preference: General model blend weighted toward 12z GFS/NAM/UKMET Confidence: Slightly above average 19z update: The 12z CMC while more amplified in the northern stream, has trended toward consensus. Likewise, the 12z ECMWF is more amplified in the southern portion of the trof in the Central Rockies but much less than the 00z run and shifted faster through the Plains. This is still slower than the GFS/NAM and UKMET but more in line with traditional spacing of deterministic guidance. Still favor the GFS/NAM and UKMET in weighting but support a general model blend at this point at slightly above average confidence. ---Prior Discussion--- An average scale and progressive positive tilt trof axis will reach the north US West Coast under fairly solid model agreement by 00z Mon and continue to translate through the Intermountain West fairly well. The 00z CMC breaks from consensus favoring a stronger amplification to the northern portion of the trof through the Northern Rockies, while not terrible to the QPF, by the time it reaches the Central Plains, the stronger northern feature manifests the surface development in the Lee of the Rockies well north of an otherwise very tight clustering. Even later in the process, the ECWMF being a bit colder aloft through the central Rockies, emerges too slow and southward typical of the ECMWF bias and a distinct outlier within the ECENS suite. While the ECENS suite is slower than the GEFS and 12z GFS/NAM it would generally support the NAM/GFS and 00z UKMET, particularly after midday Wed. As such a 12z NAM/GFS and 00z UKMET remains the preferred blend at slightly above average agreement. Upstream, perhaps due to differences in the upstream ridge from the prior system, the ECMWF produces a flat and uncharacteristically fast wave skirting WA and would be also less preferred here as well, even though the GFS/NAM are quite amplified and a sizable shift that direction from yesterday. Still, QPF by the end of the forecast period is agreeable in the warm advection scheme to keep similar preference as above. Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml 500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml Gallina