Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
154 PM EST Fri Mar 08 2019
Valid Mar 08/1200 UTC thru Mar 12/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Final Preference and Confidence
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...Departing shortwave over the eastern U.S. today...
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Preference: General model compromise
Confidence: Above average
The models remained good agreement with their previous runs and
with each other. The 12Z NAM remains on the deeper side of the
guidance while the 08/00Z Canadian was flattest. Otherwise, the
differences are small, and a general model compromise is preferred.
...Shortwave initially in Alberta/Saskatchewan tracking east and
merging with another shortwave from the north over
Saskatchewan/Manitoba on Saturday...
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Preference: non 08/12Z CMC blend
Confidence: Average
The 12Z NCEP guidance was comparable with their previous runs.
The 08/12Z Canadian largely maintained continuity with its
previous run...which leaves it on the slower/stronger side of the
guidance with the positively tilted trough axis over western
Ontario late Sunday. A non 08/12Z CMC blend is still preferred.
...Surface low tracking across the Upper Midwest/Great Lakes this
weekend...
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Preference: non 08/12Z CMC blend
Confidence: Slightly above average
Overall, the trend towards converging solutions has continued as
the start of the event approaches with only modest changes noted
in the 12Z suite of numerical guidance when compared with their
previous runs. The 08/12Z Canadian was only a bit weaker than its
previous run, so it remains one of the stronger solutions while
the 08/12Z ECMWF sped up a small amount and was slower than the
NCEP guidance but closer to the ensemble mean. For timing and
strength purposes, a non 08/00Z CMC blend will work.
...Closed low over Washington this morning, interacting with the
next Pacific trough/surface low nearing California on Saturday,
developing into a large closed low over or just offshore of
California Monday morning...
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Preference: 08/12Z NAM/GFS/ECMWF blend
Confidence: Average
Several pieces of energy coming out of the eastern Pacific will
eventually carve out a deeper trough over the west coast late in
the weekend, while interacting with a retrograding closed low over
the Pacific Northwest. There is fairly good agreement with a
surface low tracking south off of the West Coast and the eventual
formation of a large closed low that develops near the California
coast.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Bann