Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1146 PM EST Wed Jan 23 2019

Valid Jan 24/0000 UTC thru Jan 27/1200 UTC

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

00Z Model Evaluation Including Preferences and Forecast Confidence
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...Pattern across the CONUS...
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Preference: Blend of the GFS/ECMWF/UKMET through 27/00Z...then
ECMWF and UKMET
Confidence: Above Average

In the wake of the storm system currently tracking through the
central/eastern US, the synoptic pattern across the CONUS will
feature broad longwave troughing centered on the northern Plains
and Upper Midwest.  That leaves much of the United States in a
broad cyclonic flow pattern. Confidence overall remains above
normal through 48 to 60 hours with respect to the mass fields.

As is common for individual shortwave troughs embedded within a
broad, cyclonic flow...there were timing and placement differences
between the models.  One area of concern was as shortwave energy
slips over the top of a ridge off the west coast of North America
and propagates towards the Great Lakes and Ohio Valley during the
forecast period.  For the most part, the differences in handing
the shortwave energy did not result in significantly different
large scale flow patterns in the guidance, except for the Canadian
which seemed to be pulling too much energy eastward and southward
with time beginning on Day 2.  From the west coast eastward along
the southern tier of states, the GFS appeared to over amplify the
shortwave during the latter half of day 3...perhaps from
convective feedback...and was removed from the model preference.
The 00Z NAM made changes which put it in better agreement with
other operational models and the ensemble means.

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

Bann