Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
257 PM EDT Tue Aug 21 2018

Valid Aug 21/1200 UTC thru Aug 25/0000 UTC

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

12Z Model Evaluation...with Preferences and Confidence
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...Overall Synoptic Pattern across the CONUS...
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Preference: General model blend; but with less weight given to the
ECMWF over the northern Plains and upper Midwest on Thu-Fri and
with less weight given to the GFS along the Northwest coast on Fri.
Confidence: Average

**Note -- The 12z run of the UKMet was unavailable at issuance
time.**

The NAM, which was an outlier with the upper trough moving across
the eastern U.S. on Thu, has trended slower with its 12z run --
putting it into better agreement with the model consensus.

Elsewhere -- the 12z runs of the NAM, GFS, ECMWF, and Canadian
Global are in generally good agreement until late in the period
with the upstream trough moving across the northern Plains into
the upper Midwest Thu into Fri.  By late Fri, model spread starts
to increase with the ECMWF the slowest of the deterministic
solutions.  The ECMWF has trended slightly faster than its 00z run
and the overnight run of the EC Ensemble Mean is faster as well --
both suggesting the 12z ECMWF might be a little too slow at the
end of the period.

Further west -- the GFS is the slower of the solutions with a
trough moving into the northwestern U.S. late Fri -- holding more
energy offshore than the other deterministic models.  The GEFS
Mean is similar, but less amplified than the GFS.

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

Pereira