Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
122 AM EST Sat Feb 23 2019

Valid Feb 23/0000 UTC thru Feb 26/1200 UTC

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

00Z Model Evaluation...with Preferences and Confidence
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...Closed low ejecting out of the Four Corners region...
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Preference: General model blend
Confidence: Above average

The models have come into considerably better mass field agreement
with this system as it ejects out of the Four Corners region early
Saturday and then quickly lifts northeast across the Midwest and
Great Lakes region through Sunday. The system will be phasing with
an intrusion of northern stream shortwave energy as it does so,
and will then advance east across New England on Monday. A general
model blend will be preferred concerning the height fall
evolution, the strong surface track up through the Great Lakes
region, and also secondary cyclogenesis impacting coastal New
England through the period.


...Pacific Northwest trough/closed low Sun/Mon/Tues...
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Preference: Non-NAM blend, or close to the 00Z GEFS mean
Confidence: Slightly above average

Timing differences appear with a slow moving, positively tilted
upper trough and associated closed low dropping down near the
Pacific Northwest by Sunday night and a related surface low off
the West Coast that should arrive across western OR by early
Monday. The 00Z NAM is the slowest solution with the overall
height fall and surface wave evolution, and actually is notably
out of phase with the global models with the troughing over the
Pacific Northwest by later Monday and Tuesday. The global models
are clustered well toward a more progressive surface wave, with
the 00Z GFS/UKMET solutions overall the fastest, and the 00Z
CMC/ECMWF solutions a little slower. The 00Z GEFS mean favors the
more progressive global model consensus, but does suggest the
GFS/UKMET camp could be a touch too fast. Based on the latest
clustering of solutions, a non-NAM blend will be preferred, or a
solution close to the 00Z GEFS mean with the height falls and
surface low track/timing. This preference will also apply to the
broader positively-tilted trough over the Northwest by the end of
the period.


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

Orrison