Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
159 PM EST Tue Jan 29 2019

Valid Jan 29/1200 UTC thru Feb 02/0000 UTC

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

12Z Model Evaluation...with Final Preferences and Confidence
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...Overall Pattern across the CONUS...
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Preference: General model blend
 Exception: 12z GFS/12z CMC/00z ECMWF blend after 01/00z
            West Coast
Confidence: Above average

Both the 12z NAM and 12z GFS are close to the consensus/ensemble
means with respect to the large scale features across most of
CONUS through Day 3. There are some small scale differences
concerning the timing Arctic boundaries over the East, especially
from Day 1 into early Day 2. Otherwise, there is excellent model
agreement with the surface wave that forms on the front and
crosses northern New England during the second half of Day 1.

The 12z NAM remains slower than the consensus with the developing
positively tilted long wave trough approaching the West Coast,
particularly after 01/00z. In contrast, the 12z GFS has sped up
its solution (when compared with the 06z run) with the long wave
trough, and is now in much better agreement with the 00z ECMWF/00z
ECMWF ensemble mean/12z GEFS mean. The 12z CMC came into better
agreement with the consensus, and was added to the preferred
blend.

The 12z ECMWF has become faster and further southeast with the
closed mid level low at the base of the long wave trough, which
makes it an eastern outlier. Because of this, the 12z ECMWF was
not included in the preferred blend. Since the 00z ECMWF
represents a better fit with the 12z GFS/12z GEFS, it was retained
in the preferred blend.  

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

Hayes