Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1232 AM EDT Sun Aug 04 2019

Valid Aug 04/0000 UTC thru Aug 07/1200 UTC

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

00Z Model Evaluation with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of 00Z GFS, 12Z ECMWF, 12Z CMC
Confidence: Slightly above average

The synoptic pattern continues to look relatively consistent, with
a persistent ridge in the Western U.S. and a trough over the East
that gets reinforced by some digging shortwaves embedded within
deeper layer northwest flow aloft. Deterministic models are in
fairly good agreement, and ECMWF ensemble spread is below the
previous 30-day average in many areas -- indicating generally
better than average model similarity for mid-summer.

A blend of the GFS, ECMWF and CMC is preferred. Despite some
differences the mass field forecasts are relatively close, they
have good ensemble support, and a blend of those three models
should account for some uncertainty related to convective
processes and timing of fronts and shortwaves.

The 00Z NAM and 12Z UKMET are outside the envelope of NAEFS+ECMWF
ensemble height spread in some areas, mostly surrounding the
trough in the East on Tuesday and Tuesday Night. The UKMET shows a
stronger ridge over the Southwest, and a less amplified trough in
the East, only joined by a few ensemble members. Meanwhile, the
NAM shows a much stronger shortwave digging through the Upper
Midwest on Tuesday, perhaps influenced by convection in the model.
Given a lack of ensemble support, these models are not included in
the preference at this time.


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

Lamers