Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
141 AM EDT Wed Jun 19 2019

Valid Jun 19/0000 UTC thru Jun 22/1200 UTC

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

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

...Eastern and Central CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Non-NAM blend
Confidence: Slightly Above Average

Broad cyclonic flow will persist across the eastern 2/3 of the
CONUS before ridging blossoms from the Gulf Coast during Friday.
The most significant differences arise with the evolution of a
shortwave digging into a longwave trough moving from the Ohio
Valley into the northeast. The NAM is noticeably stronger with
this feature and digs 500mb heights much further south than the
remaining guidance. This has been a common thread among the NAM
with recent runs in that it strengthens shortwaves moving across
the country too deeply, and should be used with caution across the
east. Otherwise, minor latitudinal and longitudinal differences
exist in the evolution of this trough moving through on day 2, and
the ridging bulging from the Gulf on day 3, but the guidance
appears to be within the ensemble envelope so can be included in
the blend.


...Western CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: GFS/ECMWF blend
Confidence: Slightly below average

Through the forecast period an anomalously deep upper trough will
dig into the Northwest and close off near Montana. Around this
closed low, repeated pieces of shortwave energy will eject into
the west around the base of the trough creating QPF and
reinforcing the longwave trough. The GFS/ECMWF are in reasonably
good agreement with the evolution of this feature, and due to
significant discrepancies arising as early as day 2, are the
preferred blend for the west at this time. The UKMET continues to
be several DM too warm with its heights in the west, while the CMC
and NAM are too progressive with features moving down from Canada.

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

Weiss