Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1215 PM EDT Thu Jul 12 2018

Valid Jul 12/1200 UTC thru Jul 16/0000 UTC

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

12Z Model Evaluation  Final Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Model Analysis for the CONUS...

Overall Preference: 12z NAM/GFS and 00z ECMWF
General Confidence: Slightly above average
                    Slightly below average off east coast

For the next few days, most of the stronger flow aloft will be
restricted north of the US-Canada border, and thus the 500mb
heights across the CONUS generally vary by less than 50 meters at
most locations. Thus, the pattern overall lacks any significant
synoptic forcing and convective processes may be able to drive the
placement of boundaries (and future rainfall) from day to day.

The greatest spread remains just off the east coast where a
weakness in the ridge has supported a developing weak closed low
and surface cyclogenesis.  Here predictability has been low due to
the absolute strength differences in the closed low lead to larger
variation in southward extent and strength of the surface low. 
The UKMET continues to be most aggressive south and therefore
deepest with the surface low, and not likely, the ECMWF/CMC are
equally compact and dig sooner than the 06Z GFS/GEFS and so the
surface reflection lifts north under influence of a slightly
faster approach of the kicker wave.  The 12z GFS however, deepened
slightly and now better matches the ECWMF, likewise the NAM has
moved on par with the GFS/ECMWF but remains a bit east of the two.
  Overall something between the GFS/ECMWF/NAM is preferred but
with continued lower confidence.

Otherwise, the mass fields are fairly agreeable across the CONUS
with the timing of the first frontal zone through the Great Lakes
trailing through the Midwest and Central Plains on Fri thru
Sun...as well as the approach of the next deepening system with
strong frontal push through the northern High Plains/Dakotas on
Sat/Sun.   The UKMET appears a bit fast toward the end of the
forecast period while the CMC appears a bit too slow, typical of
their bias...as such it is suggested to trend away from the
UKMET/CMC Sun.


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

Gallina