Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1145 PM EST Fri Mar 08 2019
Valid Mar 09/0000 UTC thru Mar 12/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z NAM/GFS 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: non 12Z CMC blend
Confidence: Slightly above average
The 12Z CMC stands out from the remaining guidance with a stronger
and somewhat slower trough axis moving through Manitoba on Sunday.
The CMC has been trending toward the consensus but it doesn't
appear to be there just yet. Will favor a non 12Z CMC blend for
this system.
...Surface low tracking across the Upper Midwest/Great Lakes
through Sunday...
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Preference: non 12Z CMC blend
Confidence: Slightly above average
Fairly good agreement in the deterministic and ensemble guidance
with this system, but the 12Z CMC is displaced west of the
consensus with its 500 mb low by Sunday morning over the Great
lakes region. This affects the 850-700 mb low placement in the 12Z
CMC through Sunday/Sunday night with a westward deviation from the
remaining consensus. A non 12Z CMC blend shows 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: non 12Z CMC blend
Confidence: Slightly above average
The ECMWF ensemble mean has shown excellent continuity with the
timing of the eventual large closed low forecast to develop near
the California coast through Sunday night. Meanwhile, the past 4
12/00Z cycles of the GEFS has trended slower to match the ECMWF
members. Only the 12Z CMC and a couple of ECMWF ensemble members
remain fast through Tuesday morning. Decent agreement is in place
with a non-12Z CMC blend.
...Progressive upper trough approaching the Pacific Northwest
Tuesday morning...
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Preference: 00Z NAM, 00Z GFS, 12Z ECMWF blend
Confidence: Average
Model agreement is 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 ECMWF mean is faster than the 12/18Z GEFS with
the 21Z SREF slowest. The latest deterministic guidance is within
the relatively tight packing of ensemble members through 12Z/12
except for the faster 12Z CMC. A blend on the non 12Z CMC models
is recommended.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Otto