Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1243 AM EDT Fri Sep 07 2018

Valid Sep 07/0000 UTC thru Sep 10/1200 UTC

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

00Z model evaluation...with latest preferences and confidence
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...Tropical Depression Gordon...
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Preference: Non CMC blend
Confidence: Average

00Z NAM has slowed with its progression of the surface low
associated with Gordon, while the 00Z GFS sped up from its
previous solution, clustering very well with each other. Overall,
this shrinks the total spread and these now lie in the middle of
the guidance envelope which is well in line with the 18Z GEFS
mean. The CMC remains a slow outlier with Gordon which is most
evident as a deeper and further NW 700mb  low/trough axis. Despite
these differences, through 00Z/9th models are in very good
agreement with the placement of the surface low and it is really
only into day 3/Sunday when significant spread develops. A non-CMC
blend is then preferred due to overall clustering of the guidance
and little discrepancy in max QPF placement.


...Remainder of CONUS...
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Preference: Blend of 07/00Z GFS, 06/12Z ECMWF
Confidence: Slightly above average

Elsewhere, the NAM/UKMET appear to hedge towards their known bias
of fast/strong evolution with a shortwave ejecting through the
Pacific NW causing subtly faster and drier progression of a cold
front across the northern tier states late Saturday into Sunday. A
low pressure noted near FL by the CMC on Sunday is a strong
outlier from the rest of the global guidance. For these reasons a
GFS/ECMWF is preferred across the rest of the CONUS.

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

Weiss/Gallina