Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
108 AM EDT Wed Apr 01 2020
Valid Apr 01/0000 UTC thru Apr 04/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z NAM/GFS Evaluation with Preliminary Preferences and Confidence
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...Western Atlantic closed low and offshore surface low through
Friday...
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Preference: General model compromise
Confidence: Slightly above average
The models show similarly with this system despite some minor
placement differences offshore. The 12Z CMC is closest to the
coast early this morning but, along with the 00Z NAM through the
end of the week. However, a blended approach will work here as the
minor differences are all within the relatively tight model spread.
...Mid-level shortwave tracking into Saskatchewan/Manitoba through
Thursday morning with associated front into the Northern Plains...
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Preference: 00Z NAM/12Z ECMWF blend
Confidence: Average
Minor longitude differences remain with this system through
Thursday with the 12Z CMC farthest west and 00Z GFS farthest east.
The ensemble means support the middle, best represented by the 00Z
NAM and 12Z ECMWF. The 00Z NAM is strongest of the deterministic
guidance but a blended approach will temper the 00Z NAM influence
given its position looks reasonable. The 12Z UKMET is also
considered too far west.
...Mid-level shortwave moving through the Intermountain West,
reaching the Northern Plains Thursday night...
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Preference: 00Z NAM/12Z ECMWF blend
Confidence: Average
Similar to the above system, the 00Z GFS is farthest east while
the 12Z UKMET/CMC are farther west. Ensemble means support a
solution closer to the 00Z NAM and 12Z ECMWF which is the middle
ground of the latest GEFS and ECMWF means.
Concerning the related cold front which extends into the Southern
Plains, there is fair agreement among the latest deterministic
models with timing. Differences in southward placement should be
resolved with a blend of the 00Z NAM, 00Z GFS and 12Z ECMWF.
...Compact mid-level shortwave nearing the coast of northern
California Saturday morning...
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Preference: non-00Z GFS blend
Confidence: Below average
Trends in ensemble spaghetti heights have shown some clustering
but moderate differences remain. The latest cycle shows better
clustering toward the slower solutions, but the faster GFS has
been consistent while the UKMET has been trending faster. The
slower ECMWF has also been consistent. For now, will go with the
greater ensemble support, and away from the quicker 00Z GFS.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Otto