Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1230 AM EDT Fri Aug 31 2018

Valid Aug 31/0000 UTC thru Sep 03/1200 UTC

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

00Z model evaluation...with latest model preferences and confidence
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...Overall Synoptic Pattern across the CONUS...
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Preference: Blend of the 00Z GFS/12Z UKMET AND 12Z ECMWF
Confidence: Average

The large scale upper pattern will feature a series of progressive
shortwaves advancing across southern Canada and the northern tier
of the U.S. through the short range period, with the general
tendency for a mean layer trough to focus over the Intermountain
West and a rather strong mid level subtropical ridge to remain in
place over the eastern U.S. going into early next week. In fact,
the global models indicate the 500 mb ridge strengthening to over
2 standard deviations above normal across the Mid-Atlantic and
Northeast by Monday. Meanwhile, a negative anomaly of as much as
1.5 to 2 standard deviations should be situated over the Four
Corners region by then. 

The 00Z NAM and to an extent the 12Z CMC are more out of the
tolerance with the mean pattern across southern Canada and the
CONUS compared to the 00Z GFS, 12Z UKMET and 12Z ECMWF and also
the 18Z GEFS mean and 12Z ECENS mean. The 12Z NAM again remains
more amplified with an easterly wave arriving across the northwest
Gulf of Mexico. Will prefer the GFS/UKMET/ECMWF cluster of
solutions overall as a compromise at this time for 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

Orrison