Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
127 AM EDT Thu Jun 20 2019

Valid Jun 20/0000 UTC thru Jun 23/1200 UTC

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

00Z NAM/GFS Evaluation...with Preliminary Confidence and
Preferences
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...Overall Pattern Across the CONUS...
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Preference: 00Z NAM, 00Z GFS, 12Z ECMWF blend
Confidence: Average

There will be two main mid-upper level systems through Sunday
morning across the lower 48, one out West and the other exiting
the East Coast. Differences across the eastern U.S. are relatively
minor and do not escalate until the exiting trough and
corresponding surface low are near Nova Scotia. Therefore, a
general model blend should be acceptable for the East.

Out West and into the Great Plains, Timing differences show up by
Saturday morning with a shortwave in the southern portion of a
longwave trough extending from south-central Canada into the Great
Basin. The 12Z UKMET is slowest, while the 12Z CMC is fastest.
Ensemble spaghetti heights and trends over the past 4 cycles
support a middle ground which has been represented well by the
ECMWF mean. Currently, the closest middle ground is a combination
of the 00Z GFS, 00Z NAM and 12Z ECMWF.

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

Otto