Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
135 PM EST Wed Feb 06 2019

Valid Feb 06/1200 UTC thru Feb 10/0000 UTC

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

12Z Model Evaluation...with Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall pattern across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend, led by 12Z GFS/ECMWF blend
Confidence: Slightly above average

The models are in very good agreement with the mass fields
concerning the low-amplitude shortwave that crosses the OH Valley
today and lifts through the Northeast on Thursday. A general model
blend can be preferred with this feature.
 
Meanwhile, the guidance has come into much better clustering
compared to 24 hours ago concerning the ejection of the large
scale trough currently over the West which kicks out across the
central/northern Plains late tonight and early Thursday. This
trough will take on a negative tilt across the upper Midwest late
Thursday and should deepen further and close off as it crosses the
upper Great Lakes region through early Friday. The guidance is in
much better agreement with the details of the surface low pressure
track, however, the 12Z NAM does appear to be a bit stronger with
its 500/700mb layer heights falls pivoting across the upper
Midwest through late Thursday which is deeper than the global
models and is thus fostering an axis of stronger dynamic cooling
within a very well-defined deformation zone. A general model blend
will tend to suffice, but with more weighting toward the global
model consensus.

A closed mid-level low dropping south of the Gulf of Alaska is
expected to reach the central/northern CA coast on Friday and
eject inland as an open shortwave trough across the Intermountain
region through Saturday. The guidance is in very good agreement
with the timing and depth of this energy through the period which
supports a general model blend. Meanwhile, the models show the
evolution of a much stronger deep layer closed low organizing out
of the northern stream and moving down along the coastal areas of
the Pacific Northwest on Saturday. The 12Z UKMET/CMC solutions did
slow their forward progression down just a tad and are closer to
the 12Z NAM/GFS/ECMWF solutions, although the GFS now appears to
be just a tad slow.

Based on the latest model mass field trends, clustering and
ensemble spread, a general model blend led by a consensus of the
12Z GFS and 12Z ECMWF will be preferred.


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

Orrison