Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
202 AM EST Thu Dec 06 2018

Valid Dec 06/0000 UTC thru Dec 09/1200 UTC

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

00Z Model Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: General blend of the GEFS/ECENS means; 00z ECMWF
Confidence: Slightly above average

07z update: The 00z ECMWF trended more south with the surface low
and precipitation shield Saturday into Sunday across the Southeast
and Tennessee Valley. It is now one of the furthest south solution
in the deterministic model suite. The CMC/GFS are the northern
solutions. Timing wise there is better agreement but the GFS
remains the faster solution. All in all, there continues to be
spatial and thermal differences, but some clustering is beginning
on the major synoptic features. For this cycle, the WPC preference
is for a general blend of the GEFS/ECENs means with some
additional weight toward the 00z ECMWF.

---previous discussion---
A positively tilted trough off California will shift southeast to
northern Mexico through Friday and reach the southern Great Plains
Saturday. Little precipitation is expected with this system in the
CONUS until Friday when Gulf moisture is tapped over TX.
Precipitation then blossoms over the southern Plains and lower MS
Valley through Saturday as surface low pressure develops with
heavy rain threats near the Gulf Coast and wintry weather threats
inland on the north side of the precipitation shield.

Through Day 2, there is relatively good agreement with the upper
level open wave across Texas. Beyond that, both spatial and
temporal differences become significant. The GFS and the UKMET to
some degree are more progressive compared to the ECMWF solution.
The 00z NAM is stronger with the upper level low and also colder
with its thermal profiles. The 00z GFS did trend a bit colder as
well. The CMC is considered an outlier and has consistently been
too far north with the surface low track along the SE coast.

The WPC preference for the southern stream storm system is for a
blend of the GEFS and ECENS mean, weighted toward the slower ECMWF
solution for the surface/upper level synoptic features. 

The other area of notable precipitation in the CONUS in the 3-day
forecast range is with a trough approaching the coastal Pac NW
Saturday. There is pretty good agreement with the QPF fields and a
general model blend would suffice.

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

Taylor