Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
217 PM EST Fri Dec 28 2018

Valid Dec 28/1200 UTC thru Jan 01/0000 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

12Z Model Evaluation...with Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Average

19z update: Still relatively good model agreement with the rest of
the 12z guidance coming. Toward the end of the forecast period,
the UKMET appears too strong and fast as the closed low over
Mexico opens up and lifts northeast toward the Great Lakes Monday.
Otherwise, the pattern featuring longwave troughing with a
positive tilt bounded by ridging along the west/east coasts is
persistent enough for a general model blend.

---previous discussion---
Through the forecast period, the upper level flow pattern across
the CONUS is expected to feature ridging across both the west
coast and southeast US coast with longwave troughing across the
Rockies through the Upper Midwest. This will keep active storm
tracks confined mainly to the central US. The relatively
persistent pattern allows for above average model agreement. A
closed low is likely to stall/slow over the Southwest US into
portions of Mexico while in the northern stream, another strong
shortwave will drop through the Pacific Northwest. There are some
differences with how deep/far the Pacific NW trough digs, with the
UKMET the furthest south and the CMC north. A blend of the
GFS/ECMWF yields a good compromise here. In general, QPF
differences across the CONUS were minor enough. As such, a general
blend of the ECMWF/GFS/NAM is preferred at this time.


Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

Taylor