Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1118 PM EST Wed Feb 20 2019

Valid Feb 21/0000 UTC thru Feb 24/1200 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 model blend...Northwest/Northeast U.S.
            12Z ECMWF/ECENS mean blend...elsewhere
Confidence: Slightly above average

The flow pattern across the lower 48 will continue to feature
ridging over the Southeast which continues to nose in from the
Caribbean and adjacent areas of the southwestern Atlantic, with
mean troughing over the West. A shortwave meanwhile that is
stretching out from the Upper Midwest through the Great Lakes
region will shear across northern New England on Thursday.
Elsewhere, a very strong closed low will be evolving over the
Southwest Thursday and Friday. This feature will then quickly
eject east and then northeast Saturday through early Sunday from
the southern Plains to the Great Lakes region. By the end of the
period, another shortwave trough and possible closed low will be
dropping down the coast of the Pacific Northwest.

The models are in good agreement with the details of the shearing
trough and associated surface wave activity over the Great Lakes
and also coastal areas of New England through Thursday. However,
with respect to the closed low crossing the Southwest, the
guidance begins to diverge after 36 hours as the energy ejects out
across the southern Plains and ultimately the Midwest and Great
Lakes Saturday and Sunday. The 00Z NAM and 12Z UKMET begin to lag
the 12Z CMC and 12Z ECMWF solutions with the height falls and
deepening surface low progression. The 18Z GEFS mean and 00Z GFS
are more out of tolerance across the central Plains with frontal
placement Friday and Saturday and also tend to be on the slower
side of the guidance and also a bit back to the northwest of the
model consensus with the track of the surface and mid level low
centers. Overall, a blend of the 12Z ECMWF and 12Z ECENS mean will
be preferred with this system, and especially after 36 hours.
Prior to this, a general model blend would be be okay as the
energy pivots across the Southwest.

Across the Pacific Northwest by early Sunday, there will be
another shortwave trough and possible closed low arriving for
which the guidance is in rather good agreement mass field wise. A
general model blend can be preferred for now with this system.


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

Orrison