Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1220 AM EDT Fri Apr 13 2018

Valid Apr 13/0000 UTC thru Apr 16/1200 UTC

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

00Z NAM and GFS Model Evaluation with Initial Preferences and
Confidence
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...Long wave trough over the Rockies early Fri, amplifying across
the Plains/OH Valley Sat/Sun...
...Deep Surface low developing Fri over the Plains, tracking to
the OH Valley Sat/Sun...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00z NAM/12z ECMWF/12z ECMWF Mean blend
Confidence: Average

The 00z NAM was close to the model consensus tracking the the
Rockies early this morning, as it closes off over the Central
Plains tonight into Sat, before taking on a negative tilt Sun. The
00z NAM is very close to the consistent 12z ECMWF/12z ECMWF
ensemble mean positions, both at the surface and in the mid
levels. The 00z GFS was closer to the consensus through Sat, then
becomes faster with the mid level and surface systems by Late Sat
into early Sun. The faster speed affects the precipitation pattern
and temperatures in the column, so despite it coming closer to the
consensus, it is not yet ready to be included in the preference
because of the timing differences Sat into Sun.


...Long wave trough slowly dropping into the Pacific Northwest Sat
into Sun...
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Preference: General Model Blend
Confidence: Slightly above average

Both the 00z NAM and 00z GFS were close to the consensus with the
evolution of the mid level trough as it deepens and reaches the
Pacific Northwest late Sat into Sun. In fact, there was good model
agreement with the 00z/12z model suite (including ensemble means),
so a general model blend was preferred.

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

Hayes