Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1256 PM EDT Sat Jul 28 2018

Valid Jul 28/1200 UTC thru Aug 01/0000 UTC

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

12Z NAM/GFS evaluation...with preliminary preferences
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...Overall Synoptic Pattern across the CONUS...
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Preference: 12Z GFS/00Z ECWMF blend, led by the 12z GFS
Confidence: Slightly above average

Outside of smaller scale vorticity maxima, there is very good
agreement on the large scale flow across the U.S. through Tuesday.
The main feature of interest will be an area of longwave troughing
which sets up along the Mississippi River valley by mid-week,
downstream of a long standing ridge in place over the Southwest.

Ensemble means show some minor differences but show the 00Z CMC
faster along with the 12Z NAM to some degree, while the 00Z UKMET
is flatter with the trough axis. The 00Z ECMWF slows slightly
slower with this trough's progression into the middle of the week
with even the 00Z ECMWF ensemble mean a bit ahead of the
deterministic ECMWF. Given the meridional pattern over the lower
48, do not want to go too fast, with a blend of the 12Z GFS/00Z
ECMWF preferred, but with a bit more weight on the somewhat faster
GFS.

Elsewhere across the U.S., a general model blend is acceptable
given good agreement.

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

Otto