Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
302 PM EDT Mon Aug 27 2018

Valid Aug 27/1200 UTC thru Aug 31/0000 UTC

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

12Z Model Evaluation with Preference and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Synoptic Pattern across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 12Z GFS... supported by run to run continuity and the
12Z GEFS
Confidence: Average

One medium wavelength trough will lift through the Upper Midwest
toward eastern Canada, dragging a cold front into the
central/eastern United States. Another medium wavelength trough
will drop in to replace it over the northern / northwestern part
of the country.

Models are generally in good agreement on the movement and
evolution of these large scale features through 31/00Z. The
solutions are clustered well enough that a blend of the
operational models could be effective. For some of the details,
however, we prefer the GFS for its run to run continuity, and
particularly for maintaining some semblance of a trough as the
feature currently in the Great Basin lifts toward eastern Canada
and New England. The ECMWF and its ensemble flatten the feature so
that it is unrecognizable in the 500-mb height pattern by Day 3.
Overall, this has fairly minimal effect, as all the models are
still fairly similar in their frontal positions over the United
States through Day 3.

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

Burke/Weiss