Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
213 AM EST Thu Jan 24 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/GFS/Ensemble Mean
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 big-picture of
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 with shortwave energy
slipping over the top of a ridge off the west coast of North
America and then propagating 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 still seemed to be pulling too much
energy southward with time on Day 3.  Over the western U.S.,
shortwave energy dropping south on the periphery of a mid/upper
level ridge/high anchored off the coast, the models have been
struggling in how much amplification will occur over the Southwest
U.S./northern Mexico late on Day 3. The 24/00Z UKMET was a
sharp/fast outlier as the energy makes its way through Mexico. 
Think the GFS overall looked okay...with the exception of how
sharp the trough was over South Texas in the last 6 to 12 hours of
Day 3. Making the assumption that the GFS will end up being
somewhat flatter than depicted by the 24/00Z run, a ECMWF/Ensemble
Mean and GFS should work as a compromise.

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

Bann