Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1246 AM EDT Sun Aug 12 2018

Valid Aug 12/0000 UTC thru Aug 15/1200 UTC

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

00Z NAM/GFS evaluation with preliminary preferences
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...Overall Synoptic Pattern across the CONUS...
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Preference: 00Z GFS, 12Z ECMWF blend
Confidence: Average

With a closed low over the northern Mid-Atlantic region, timing
differences appear by Tuesday/Wednesday. The 00Z GFS begins to
nudge faster while the 12Z UKMET is significantly slower. a middle
ground away from the 12Z UKMET is best with this system.

Over the Northwest, a closed low will deamplify as it tracks
east-northeastward with only the 00Z NAM showing significantly
different (slower) than the remaining model consensus, although
the 00Z GFS is a bit faster (typical bias). Greater differences
appear with the trailing mid-level vort axis across Montana and
the northern High Plains with large ensemble spread. Smaller scale
differences also show up with the northeastward movement of a
relatively broad shortwave trough over the southern/central Plains
Tuesday into Wednesday. With these features a blend is preferred
with a greater weight on the 00Z GFS/12Z ECMWF given better
placement within the greater ensemble clustering..

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

Otto