Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
313 PM EDT Sat Aug 25 2018

Valid Aug 25/1200 UTC thru Aug 29/0000 UTC

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

12Z Model Evaluation and Preferences with Confidence
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...Overall Synoptic Pattern across the CONUS...
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Preference: 12z ECMWF/12z GEFS Mean/12z UKMET Blend
Confidence: Slightly Above Average

Good agreement remains with large scale features through the
forecast period with the 12Z NAM/GFS. This includes the
deamplification of the upper trough as it moves northeast across
Great Lakes and into southeast Canada today and New England
Sunday.

The attention shifts west with the amplification of the trough
over the western US and progression east to the Great Lakes
through Monday.

The 12Z GFS/NAM/12z ECMWF/12z UKMET are in excellent agreement in
terms of heights/pressures and precipitation through Monday with
the trough motion over the northern Great Plains. The GFS is
slightly more amplified with its 700 mb wave in the Dakotas Monday
and the upper MS Valley Tue, with a slightly stronger wave of low
pressure on the front.

The frontal timing across the Plains to the upper MS Valley and
upper Great Lakes has pretty good timing agreement, lending the
situation to a consensus based forecast, given typical timing
differences of waves along the front.

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

Petersen