Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
108 AM EDT Fri Jun 01 2018

Valid Jun 01/0000 UTC thru Jun 04/1200 UTC

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

00Z NAM/GFS evaluation...with preliminary preferences
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...Upper trough crossing the Great Lakes/Ohio Valley today and
Mid-Atlantic Sat/possibly off the coast Sun...
...Coastal low off of the northern Mid-Atlantic coast through
Monday morning...
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Preference: Blend of 00Z GFS/12Z ECMWF/12Z UKMET
Confidence: Average

Some latitude differences exist with the placement of a surface
low off of the Mid-Atlantic coast. Trends in the ensemble scatter
low plots support a middle ground best represented by a 00Z
GFS/12Z ECMWF/12Z UKMET blend with the 00Z NAM on the far southern
edge of the ensemble spread and 12Z CMC on the northeast side of
the available ensemble members.


...Upper trough crossing the northern Rockies this
morning...northern Plains tonight, and upper MS Valley Sat night...
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Preference: Blend of 00Z NAM, 00Z GFS and 12Z ECMWF
Confidence: Slightly below average

The models show varying degrees of evolution with the southern end
of a negatively tilted trough axis crossing the upper MS valley
Saturday night. The 00Z NAM is perhaps the weakest with the
strength of energy in the base of the trough axis, but its
placement matches well to the GEFS and ECMWF means. The 00Z GFS is
the strongest of the 3 models (NAM, GFS, ECMWF) while the 12Z
ECMWF is a bit weaker and faster. A blend of the 00Z NAM, 00Z GFS
and 12Z ECMWF matches best to the agreeable ensemble means with
the 12Z UKMET and 12Z CMC not supported in the latest ensembles,
although none are outliers. Confidence is a bit below average
given the poor model agreement and run to run consistency.


...Mid-level vorticity maximum entering the Southwest U.S. on
Saturday...
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Preference: General model blend
Confidence: Slightly above average

The models show similarly with this system.


...Upper trough impacting the Pacific Northwest Sunday/Monday...
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Preference: General model blend
Confidence: Average

The models show minor differences with this system given the 60-84
hour forecast range of this system. Given the relatively small
spread, a general model blend is preferred to smooth out these
smaller scale differences.


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

Otto