Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1244 PM EDT Tue Apr 23 2019

Valid Apr 23/1200 UTC thru Apr 27/0000 UTC

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

12Z Model Evaluation...with Preliminary Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: Non 23/12Z NAM model compromise
Confidence: Average

Models were in generally good agreement through 25/00Z (Wednesday
evening), with a similar synoptic pattern and limited model
spread. After that, there is a divergence related to northern
stream shortwaves digging into the Great Lakes and headed towards
the East Coast, the southern stream trough ejecting out of Texas,
and the interaction of the two. The 23/00 ECMWF (and its ensemble)
were generally stronger with shortwave energy in the northern
stream with lower heights aloft.  The 23/12Z GFS made moves
towards the ECMWF idea, although there is enough spread that using
a blend of the two models should mitigate some of the timiing
concerns.  The 23/12Z NAM, by contrast, still lags the southern
stream trough more, have weaker northern stream shortwaves, and
show less phasing. The 23/00Z UKMET and CMC offer somewhat of a
compromise in their mass fields and QPF patterns. The preference
is to go with a non-NAM-based model blend.

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

Bann