Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
102 AM EDT Sat Jun 22 2019

Valid Jun 22/0000 UTC thru Jun 25/1200 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

A longwave trough in place over the western 2/3 of the U.S. will
be the main area of focus for the weather across the lower 48
through Tuesday. The biggest difference lies with a shortwave in
the base of the trough crossing the central Rockies and reaching
the central Plains Sunday. This is when the 12Z UKMET begins to
show weaker with the vorticity max in the base of the trough while
also appearing slower than the remaining model consensus. The 12Z
CMC on the other hand is stronger with the core of the mid-level
trough by Monday morning and winds up with a much stronger surface
reflection that is not supported in the remaining guidance.
Ensemble clustering best supports a blend of the 00Z NAM, 00Z GFS
and 12Z ECMWF through Tuesday morning, although the surface low
from 12Z ECMWF appears on the southern side of the ensemble spread
by Tuesday morning near the Great Lakes/southern Ontario. A blend
of the more southern 12Z ECMWF with the farther north 00Z GFS/NAM
affords a reasonable blend, more in line with the latest ensemble
means.

Elsewhere across the CONUS, model agreement was close enough to
support a general model blend.


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

Otto