Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
313 AM EDT Fri Mar 20 2020
Valid Mar 20/0000 UTC thru Mar 23/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00z Model Evaluation with Latest Preferences and Confidence
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...Low pressure and cold front crossing the Upper Great Lakes and
Northeast...
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Preference: General model blend
Confidence: Above average
For the big surface low exiting the Great Lakes region Friday and
the trailing cold front across the Appalachians and reaching the
East Coast Friday night, a multi-deterministic model blend should
suffice given good agreement on timing of cold frontal passage.
...Mid level troughs affecting the Northern Plains into the Upper
Great Lakes...
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Preference: 00Z GFS/00Z ECMWF
Confidence: Average
For the first short wave tracking out of central Manitoba, the 00Z
NAM is still a little stronger than the other guidance as it
reaches North Dakota midday Saturday, but not to the degree
indicated in earlier runs, and the 00Z CMC is slightly slower
compared to the consensus with regard to timing. For the second
short wave tracking from Alberta into the Northern Plains by
Sunday morning, the 00Z NAM is more amplified with the wave and
the UKMET is slightly slower. The GFS becomes more progressive by
Sunday night as the wave crosses Minnesota. A blend of the
GFS/ECMWF should serve well as a starting point in the forecast
since they have good ensemble support.
...Mid level trough crossing the Southwest Saturday...
...Closed mid level low approaching Central California Sunday...
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Preference: 00Z GFS/00Z ECMWF
Confidence: Average
A lead shortwave trough approaching southern California Saturday
morning is forecast to track across the Desert Southwest and reach
the central Plains by Sunday. The deterministic models are in
good agreement on timing through Saturday, with the exception of
the slightly weaker EC mean. By Sunday morning the NAM is more
amplified and is not favored.
A closed mid level low follows behind this shortwave and wobbles
toward the Central and Southern California coast by Sunday night.
With this feature, the 00Z ECMWF trended faster although its mean
is slightly slower than the other guidance by Sunday night, and
the GFS is closer to the consensus timing compared to earlier
runs.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Hamrick