Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
318 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 Model Evaluation...with Final Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: non 00Z UKMET blend
Confidence: Average

...07Z update...

Changes seen with the mid-level trough for Monday include a weaker
trend from the 00Z CMC compared to its previous 12Z cycle toward
the remaining model consensus. The 00Z CMC surface low strength
and position more closely match that of the 00Z NAM and 00Z GFS.
The 00Z ECMWF trended slightly north with its vorticity max within
the core of the mid-level trough, allowing its surface low to
track north closer to the previous middle ground preference and
closer to the better ensemble clustering. The 00Z UKMET did not
significant change, however, so the final preference will be for a
general model blend excluding the 00Z UKMET.

...previous discussion follows...

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