Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
106 AM EDT Wed Aug 15 2018

Valid Aug 15/0000 UTC thru Aug 18/1200 UTC

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

00Z NAM/GFS evaluation including preliminary preferences
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...Overall Synoptic Pattern across the CONUS...
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Preference: 00Z GFS / 12Z ECMWF blend
Confidence: Slightly above average

The greatest uncertainty lies across the northern Plains to the
Ohio Valley concerning the evolution of a weakening closed low
currently over the middle Missouri Valley and an upstream
shortwave over southeast Montana. These two features will track
generally toward the east with longwave troughing setting up over
the eastern third of the nation by Saturday morning.

At the surface, a low will track from Kansas/Missouri toward
Chicago Thursday morning and southern Ontario Friday morning. 
GEFS/ECMWF/CMC ensemble low plots show decent agreement as do the
ensemble means, but the deterministic models are on either side of
the good ensemble agreement. The 00Z GFS is slower/west with the
low track, while the 12Z ECMWF and 00Z NAM are a bit east/faster.
The 12Z UKMET/CMC were a tad north of the better consensus and a
bit more progressive with the overall 500 mb trough translating
into the Appalachians by Saturday morning. The preference is a
blend led by the 00Z GFS and 12Z ECMWF, with neither model showing
ideal and the middle ground being preferred.

Elsewhere, model agreement is reasonably good for mass fields,
with the exception of the stronger mid-level trough seen in the
12Z CMC along the West Coast on Friday.

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

Otto