Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
159 PM EDT Thu Aug 02 2018

Valid Aug 02/1200 UTC thru Aug 06/0000 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: Model blend weighted most toward 00Z ECMWF and least
            toward 12Z GFS and 12Z CMC.
Confidence: Average

Model differences begin to increase as the relatively unchanged
pattern over the past several days begins to break down. The
trough over the Mississippi River Valley will begin to lift out to
the Northeast, paving the way for a series of waves in the
northern tier of states in increasingly zonal flow.

Although model differences do become larger, the deterministic
models are still reasonably close with their synoptic patterns,
and all generally fit within the envelope of ensemble spread
(NAEFS+ECMWF). Therefore, a general model blend is preferred, but
with greater weighting toward the 00Z ECMWF, and less weighting
toward the 12Z GFS and 12Z CMC.

The GFS and CMC show greater differences from the consensus
forecast overall. For example, the 12Z GFS is flatter with the
trough as it lifts out through the Northeast this weekend, and
does not amplify a shortwave ridge over the Northwest in advance
of a large closed low dropping down the west coast of North
America. The 12Z CMC carries stronger shortwaves through the zonal
flow and as a result has lower heights with some troughs out of
phase from other models over the northern portions of the country.
The 00Z ECMWF offers a fairly consistent scenario that is also
close to the ECMWF Ensemble Mean.


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

Lamers