Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
246 PM EDT Sun Mar 10 2019
Valid Mar 10/1200 UTC thru Mar 14/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Initial Preferences and Confidence
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...Positively tilted shortwave trough moving east into Manitoba
and Ontario into Monday morning...
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Preference: General model blend
Confidence: Average
Only minor timing/depth differences remain with this system. The
10/12Z NCEP runs and the 10/00Z ECMWF still had the support of the
latest ensemble means. The 10/12Z UKMET/CMC. A general model
blend should handle these differences adequately.
...Surface low tracking north of the Great Lakes this evening
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Preference: General model blend
Confidence: Average
Differences with this system are small enough such that a general
model blend can be used.
...Large closed low forming just offshore of California Sunday
night and tracking through Arizona and New Mexico to Kansas on
Wednesday
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Preference: 10/12Z GFS/NAM/ECMWF blend
Confidence: Average
The model agreement is pretty good through the Day 2 forecast
period with respect to the track of the closed low. However,
spread opens up towards the end of Day 3 as the mid-level center
makes a curve towards the north/northeast and takes on a negative
tilt. The 10/12Z NCEP guidance was close to the solutions they
offered in previous runs, so the Canadian remained on the slower
side of the guidance. The 10/12Z UKMET continued its idea from
its previous run of lifting the center northeast into Kansas well
before the other guidance...which seems a bit too fast. So will
recommend a blend of the 10/12Z runs of the GFS and ECMWF to
mitigate some minor timing differences between the two models.
Note this solution ends up being fairly close to the ensemble
means. The 10/12Z NAM palcement also looks fine at the end of Day
3...but the depth may end up being a tad on the weak side.
...Progressive upper trough approaching the Pacific Northwest
Tuesday morning...
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Preference: General model blend
Confidence: Average
The 10/12Z CMC favored the slower solution to bring a surface low
to the coast of British Columbia on Monday. Sensible weather
impacts, though, remain north of the border. Otherwise, the
deterministic and ensemble guidance shows good agreement.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Bann