Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1250 AM EDT Sat Aug 17 2019

Valid Aug 17/0000 UTC thru Aug 20/1200 UTC

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

00Z Model Evaluation...Including Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Pattern Across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Blend of the 12Z GFS, 12Z ECMWF, and ECENS/GEFS mean
Confidence: Slightly above average through day 2, below average on
day 3

The large scale flow across the CONUS will remain broadly cyclonic
through the weekend, although gradual height rises are expected by
later Sunday and early next week across the central and southern
U.S. Shortwaves rotating through the flow will be the primary
sensible weather makers, and it is discrepancy among these
features that lead to the preferred blend.

The most notable differences involve the 00Z NAM which continues
to be a relatively strong outlier with several of these vort lobes
impacting the Plains/Midwest that are shedding around a complex of
upper lows in Canada. In fact, the NAM gradually becomes out of
tolerance with the global model consensus across much of
central/southern Canada by the end of the period. The 12Z UKMET
also is problematic with energy it has lifting up across the upper
Midwest through early Sunday as it is sharper and stronger with a
surface wave lifting up along a cold front crossing this region.
The UKMET also is out of tolerance across Canada versus the model
consensus, which is strongly supported at this point by the 00Z
GFS and 12Z ECMWF overall.

There is strong support toward a GFS/ECMWF blend out of the latest
GEFS/ECENS means, and thus a blend of all of these will be
preferred at this point across the CONUS.


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

Orrison