Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1214 AM EDT Fri Aug 03 2018

Valid Aug 03/0000 UTC thru Aug 06/1200 UTC

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

00Z Model Evaluation Including Preference and Forecast Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Synoptic Pattern across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Non-NAM blend favored most to the 12z ECMWF/UKMET
            Include CMC in Northeast, include 00z GFS in Central
US
Confidence: Slightly above average

Deep latitude trof over the east is breaking down quickly in the
short term but the trailing wave currently in GA will phase with
compact shortwave rounding the southeast side of the subtropical
ridge as both lift into the Northeast by Sat.  The 00z GFS
continues to be quick with reduced phasing, while the ECMWF, CMC,
and UKMET show greatest agreement in the center of the ensemble
suite (GEFS/CMCE and ECENS),  While the 00z GFS is fast, it at
least showed a similar track/placement while tracking up the
coast; this is opposed to a more amplified/wound up NAM solution
that was well north of the ensemble means.  As such would favor
away from the NAM/GFS in the Northeast. 

Into the southeast Gulf of AK, a very strong/vast closed/stacked
low is fairly well agreed upon with only very small timing
differences within the inner core of the upper low itself, enough
to support a general model blend at above average confidence here.
  It is between this deep low and the weakening deep latitude wave
over the East, that highly variable, weak shortwave features
provide larger scale zonal flow, but more synoptic waviness that
eventually amplifies into a larger broad trof across central
Canada into the Northern Tier of the US by Sunday into Monday.  A
lead wave currently in the central Rockies, rounding the top of
the Southwest ridge, will amplify as it slides northeastward into
Ontario...here the NAM is clearly over amplified, though the 12z
CMC looks a bit slower but deeper as well.  The CMC is not
terrible out of phase with the 00z GFS and 12z UKMET/ECMWF and the
ensemble suite, but may be best to weight lower for this
combination of smaller scale waves as that grow upscale by Monday.
 Confidence is a bit reduced for this feature but only slightly
so. 

All in all, a Non-NAM blend is supported across much of the CONUS
but reduce the CMC in the north central US (Canada) and eliminate
the 00z GFS in the northeast for greatest forecast confidence
(slightly above average).

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

Gallina