Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1225 AM EDT Sun Jun 10 2018

Valid Jun 10/0000 UTC thru Jun 13/1200 UTC

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

00Z Model Evaluation...with Preliminary Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Model analysis for the bulk of the systems in the CONUS...

Preference: 00Z GFS; 12Z ECMWF; 12Z ECMWF Ensemble
Confidence: Slightly above average

As the flow pattern becomes more zonal with a larger mid-upper
level anticyclone building into the southern Plains, model
differences become more noticeable. Differences in the timing and
amplitude of individual waves begin to have a more substantial
impact on the mass fields. In general, the preference across most
of the CONUS is anchored by the 12Z ECMWF Ensemble and 00Z GFS.
Despite some trending over the past several model cycles, the
ECMWF Ensemble mean has remained fairly consistent, and it shows
excellent continuity over the past two runs. The new 00Z GFS is
similar to this, having adjusted its position of the southern
Plains ridge (which has additional effects on the orientation of
the flow in the Northwest).

By comparison, the 12Z CMC remains much further east with its
ridge axis, leading to more troughing across the West by 13.12Z
(Wednesday morning). The 12Z UKMET is somewhat similar, but to a
lesser extent. The UKMET and CMC also show flatter flow through
the Northeast and Mid Atlantic early this week while most of the
other models show a shortwave trough. Given these discrepancies,
they are not included in the preference. The 00Z NAM continues to
be much stronger with its convectively-induced shortwaves, which
tend to have growing effects on the mass fields with increasing
forecast time.


...Ohio Valley to Mid Atlantic Corridor...

Preference: 00Z GFS
Confidence: Slightly below average

As has been the case for the past several days, there is
uncertainty with the timing and strength of shortwaves propagating
east from the Midwest through the Mid Atlantic. In this region,
convective processes may exert a larger than normal influence on
the pattern given a lack of significant synoptic features. The WPC
preference generally remains consistent to trend the QPF toward
the southern end of model spread, as is common in situations with
several waves of convective clusters -- they will trend toward the
reservoir of greater instability. The 12Z ECMWF remains further
north, maintaining an MCV currently in SC MN at much greater
strength than other models. This leads to a northward shift in its
QPF and even other effects such as a coherent surface low. In
general, things were trended toward the GFS in this region.


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

Lamers