Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1206 AM EDT Fri Nov 01 2019

Valid Nov 01/0000 UTC thru Nov 04/1200 UTC

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

12Z Final Model Evaluation with Preferences and Confidence
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CONUS through 84hrs (04/12z)
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Preference: General model blend
 Exception: Non-NAM across Northern Plains/Great Lakes after 03.12z
Confidence: Above average; slightly above average after 03.12z

Mature, occluded cyclone across the Eastern Great Lakes with
frontal zone pressing off the Mid-Atlantic coast will progress
across the Northeast later today, under very strong model
agreement.  Afterward, a deep, broad, global-scale trough will
dominate the the North American continent with a strong upstream
ridge across the SE Gulf of Alaska/Northeast Pacific.

Internal of the broad trough will be small scale shortwaves moving
out of the northwest flow in Canada, the first will amplify across
Ontario with a surface wave moving along the northern periphery of
the Great Lakes Sat into Sunday.  Guidance has come into very
strong agreement with this system as well so a general model blend
across the CONUS can be support at well above average confidence
through 03/00z.  It is the next shortwave that is currently in the
Bay of Bristol in SW AK, that lingers some uncertainty.  It is
minor, but typical biases manifest, with the 00z GFS being fast
but weaker like the 12z UKMET and the 12z ECMWF/CMC paired slower
but equally flat.  It is only the 00z NAM that shows a much
stronger amplification with increased QPF as well, given the
origin and the prolonged northwest flow ushering in colder air
from the Arctic, there is increased confidence that the NAM is
showing typical negative bias at day 3 and is not preferred. 
Otherwise, the timing differences in the GFS/UKMET and the
ECMWF/CMC can be split with an equal non-NAM blend preference
after 03.12z.  Given the spread, confidence after 03.12z is
reduced to slightly above average.

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

Gallina