Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
242 PM EDT Mon Jun 10 2019

Valid Jun 10/1200 UTC thru Jun 14/0000 UTC

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

12Z Model Evaluation...with Confidence and Preferences
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Pattern Across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Blend of the 12Z ECMWF/CMC/UKMET/GFS through 12/12Z
Preference: Blend of the 12Z ECMMWF/CMC/UKMET from 12/12Z-14/00Z
Confidence: Above average


...19Z Update...

Model preferences have been adjusted a bit at this update given
the 12Z ECMWF is now well clustered with the 12Z CMC/UKMET with
the 12Z GFS out running the rest of the model guidance by the end
of the period.  Therefore, the model blend of choice will be
closely tied to the 00Z EC/12Z GFS ensemble mean. 

...Previous Discussion...

A longwave trough axis across the central CONUS will remain
somewhat anchored as a series of mid-level shortwaves continue to
pivot through the Ohio Valley through the period.  This will
result in a few areas of disturbances that will impact mainly the
eastern half of the U.S. 

As the trough axis and shortwave energy cross the Ohio Valley
through Monday night, expect the associated cold front to march
eastward with shower/thunderstorm activity initiating ahead of the
boundary.  It appears all model guidance are in generally good
agreement with the frontal passage, associated mass fields and the
resulting QPF totals.  As the trough continues to become
negatively tilted helping the energy lift off the Northeast coast,
surface high pressure will briefly build into the region. 
Meanwhile, aloft, all models indicate another shortwave coming out
of the northern Rockies Tuesday as noted by the mid-level
vorticity and jet axis diving into the Plains.  Again, all models
are in fairly good agreement with this next piece of energy with
strong ridging across the west coast.  Mid-level impulses will
continue to dive south with height falls farther east across the
Great Lakes region with surface low development.  By Wednesday, it
appears the differences among the model guidance become slightly
more evident. 

With a strong jet axis of >130 knots moving into the northern
Plains and a resultant amplified trough pivoting into the MS
Valley, a sharpening jet moving into the Northeast will act as a
catalyst for surface low development across the Southeast.  The
right entrance region of the jet is well positioned for strong
ascent across south GA into the Carolinas.  The model differences
with respect to mass fields are hardly noticeable associated with
this system, but based on the QPF amounts, it is clear that model
difference exist.  Upon further investigation, it appears the
surface coastal low and mid-level energy become phased with the
aforementioned surface low across the Great Lakes region as seen
by the 00Z EC and 12Z NAM.  Meanwhile, the 12Z GFS is not phased
and is slightly more progressive with its dynamics as seen by the
jet streak moving offshore and shortwave impulses farther east
than the rest of the model guidance.  While it may be easy to toss
the latest GFS, it has shown this solution the last couple of
model runs with continuity a factor worth considering.  Therefore,
have kept it among the blend with perhaps slightly less weight
than the better clustered ECMWF/NAM solutions during this time and
location. 

The UKMET throughout the period seemed a bit too weak and fast to
have much confidence within this model solution which has been
observed the last couple of runs.  The 12Z GFS/NAM and 00Z ECMWF
seems to be fairly well aligned through the remainder of the
period as the trough becomes negatively tilted with the associated
surface low across the Great Lakes lifting into the Northeast. 

By the end of the period, Thursday into Thursday night, a
developing surface low on the lee side of the Rockies seems to be
well clustered by the models (GFS/CMC/EC/NAM) as well while the
UKMet continues to show a bit of weakness, especially with respect
to the upper level mass fields. 

Given the above logic, the model preference for the CONUS will
lean toward a blend of the 12Z GFS and 00Z ECMWF with some
consideration toward the 12Z NAM and 00Z CMC.

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

Pagano