Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1145 AM EST Sat Mar 09 2019
Valid Mar 09/1200 UTC thru Mar 13/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Preliminary Preferences and
Confidence
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...Positively tilted shortwave trough moving east into Manitoba
and Ontario this weekend...
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Preference: 09/00Z UKMET/Canadian excluded from a general model
compromise
Confidence: Slightly above average
The 12Z guidance largely kept continuity with this feature,
leaving the 09/00Z UKMET on the slow side of the guidance while
the 09/00Z Canadian was near the consensus value...but not quite
there yet.
...Surface low tracking across the Upper Midwest/Great Lakes
through Sunday...
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Preference: 09/00Z UKMET and 09/12Z NAM excluded from a general
model compromise
Confidence: Slightly above average
Overall, the models and the ensemble guidance remained in fairly
good agreement with this system, but the Canadian remains
displaced west of the consensus with its 500 mb low by Sunday
morning over the Great lakes region and the NAM appeared to be
overly aggressive with a trailing shortwave that closes off a
mid-level low briefly near the western tip of Lake Superior at the
start of the Day 2 forecast period. Otherwise, a blend of
remaining models tends to show good agreement and is recommended
here.
...Closed low over Washington this morning, interacting with the
next Pacific trough/surface low nearing California later today,
developing into a large closed low over or just offshore of
California Monday morning...
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Preference: General model blend
Confidence: Average
The 12Z NCEP guidance maintained good continuity with the large
scale picture and the smaller scale details from their earlier
runs...thus maintaining a good degree of agreement between the
operational runs, ensemble guidance and 09/00Z non-NCEP runs. No
change in preference was made from the overnight shift.
...Progressive upper trough approaching the Pacific Northwest
Tuesday morning...
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Preference: 09/12Z NCEP and 09/00Z ECMWF blend
Confidence: Average
Model agreement was not as good with this system compared with the
ones above. The ensemble means differ on the timing of the next
shortwave trough to affect the Pacific Northwest Monday night into
Tuesday. The 12Z NCEP guidance and the 09/00Z ECMWF were closest
to the ensemble means, which is probably the best place to be
given the spread in the guidance.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Bann