Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1134 AM EST Wed Dec 05 2018

Valid Dec 05/1200 UTC thru Dec 09/0000 UTC

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

12Z NAM/GFS Model Evaluation...with Preliminary Preferences and
Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Pattern Across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend, highest weight to 00Z ECMWF
Confidence: Slightly Above average

An opening low off California today will shift southeast to Mexico
as a trough 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 in advance 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.

Good agreement is seen among global guidance with the trough
position and depth until Saturday when timing and magnitude
differences become apparent. The 12Z GFS is less progressive than
prior runs and is closer to the consensus. This slowing brought
the 12Z GFS enough into the fold to be considered for the
preference. The preference is still weighted toward the 00Z ECMWF
which is deeper and slower, but in line with the ECENS mean and
12Z NAM. The 00Z UKMET is as progressive as the 12Z GFS.

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

Jackson