Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1229 PM EDT Sun Jun 17 2018

Valid Jun 17/1200 UTC thru Jun 21/0000 UTC

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

12Z Model evaluation including preferences and forecast confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall model diagnostic analysis for the CONUS...
......(with exception to section below)......
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 12z NAM and 00z ECMWF/UKMET blend
Confidence: Above average thru 20/00z...average afterward

Models show very good agreement of the western closed low and
developing global-scale trof over the Northeast through 20/00z. 
including placement, timing of shortwaves moving out of the
Rockies into confluent flow across the Upper Midwest and the
surface waves traveling along the frontal zone that will slowly
sag south.   As the closed low breaks down and the Southwestern
Ridge begins to dominate, much of the guidance slides the
remaining energy into the weakness over the Central Plains Wed,
the 12z GFS, showing a stronger and wide ridge is slow but with
more energy injected from the Western Gulf, slows and descends a
bit too far south...as well as delaying the shortwave out of the
sub-tropical EPAC toward the West Coast by 00z Thurs.  Thirdly,
the 12z GFS is quite robust with the Southeastern ridge too; all
leading to a less favorable GFS solution compared to the remaining
guidance and ensemble suite/trends.  The 00z CMC is also a bit
less preferable as well given the eastward bias of the break down
of the upper low and as such the progressive nature eastward after
Wed as well.  Confidence is above average with the strong
agreement through 00z Wed (20th) but breaks down to average
afterward.


...Broad TUTT Cell and low level easterly tropical wave
progressing through Western Gulf with high moisture flux possible
surface low in NE Mexico by Late Mon to Thurs...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 17/00Z GFS/ECMWF blend
Confidence: Below average

Large model spread remains both in the deterministic guidance and
internal ensemble members with respect to the development of this
TUTT and surface wave.  The 00z UKMET and ECMWF both develop a
very strong/consolidated convective response shedding very little
energy into the northern stream mid-level weakness.  However,
cluster analysis in the 50 member ECENS suite shows a large
variety of potential outcomes, likely none as consolidated/robust
as the UKMET and very few near the operational EC.   The 12z
NAM/GFS both suggest a much stronger ridge over Mexico as well as
over the Eastern Gulf with increased energy shed to the northern
stream; yet the NAM having more convective feedback also
strengthens the northern portion of the easterly wave/inverted
trof over NE Mexico into TX.  The CMC appears like a slow ECMWF
solution or a NAM solution that does not shed energy into the
northern steam, which is a change from prior runs over the last
few days and fits nicely in the middle of the overall solution
package, representing a small majority of ensemble members. 
Overall the trend continues to tip toward a stronger/deeper more
consolidated response, but not as dramatic as the ECMWF or UKMET. 
As such a preference toward the 00z ECENS mean/CMC solution is
preferred at below average confidence.

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

Gallina