Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1243 PM EDT Mon Aug 19 2019

Valid Aug 19/1200 UTC thru Aug 23/0000 UTC

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

12Z Model Evaluation...Including Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 06Z GEFS mean/00Z ECENS mean
Confidence: Average

Mid to upper level ridging will persist through the forecast
period across the southwest U.S. while the northern stream energy
will become increasingly amplified featuring two troughs, one over
the Pacific NW and another across the Great Lakes region.

In the first 48 hours, model agreement is above average with
little spread seen in the 500 mb heights across the CONUS. As a
result, a general model blend can be applied for the mass fields.
Beyond this time frame, some notable differences are observed,
especially with the troughs across the NW and Great Lakes regions.
Typical model biases were seen, with the GFS and NAM being a bit
faster with the trough progression in the NW and fast and further
NE with the trough over the Great Lakes. The 00Z CMC was too deep
over the western US compared to the rest of the model guidance.

Based on this, the preference is for a blend of the GEFS mean and
ECENS mean, which seem to smooth the timing biases seen in the
deterministic runs and offer a compromise solution at this time.


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

Taylor