Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
240 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 Model Evaluation with Final 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 and 00Z CMC are closest to
the coast early this morning 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. No significant changes were noted with the 00Z
ECMWF/UKMET/CMC compared to their previous 12Z cycles.
...Mid-level shortwave tracking into Saskatchewan/Manitoba through
Thursday morning with associated front into the Northern Plains...
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Preference: 00Z NAM/ECMWF/UKMET blend
Confidence: Average
Minor longitude differences remain with this system through
Thursday with the 12Z CMC and 00Z CMC farthest west and 00Z GFS
farthest east. The ensemble means support the middle, best
represented by the 00Z NAM/ECMWF/UKMET. The 00Z NAM is strongest
of the deterministic guidance but a blended approach will temper
the 00Z NAM influence given its position looks reasonable when
blended with the farther west 00Z ECMWF/UKMET. The 12Z UKMET is
considered too far west but the 00Z UKMET trended east while the
00Z ECMWF trended west through Thursday morning.
...Mid-level shortwave moving through the Intermountain West,
reaching the Northern Plains Thursday night...
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Preference: 00Z NAM/ECMWF/UKMET blend (least weight on UKMET)
Confidence: Average
Similar to the above system, the 00Z GFS is farthest east while
the 00z CMC and 12Z UKMET are farther west. Ensemble means support
a solution closer to the 00Z NAM and 00Z ECMWF/UKMET which is the
middle ground of the latest GEFS and ECMWF means. No significant
changes were noted with this system from the 00Z ECMWF but the 00Z
UKMET did trend a little east from its previous cycle, such that
some of the UKMET can be used with the 00Z NAM/ECMWF blend.
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 00Z 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. The slower ECMWF has also been fairly consistent.
The 00Z ECMWF and UKMET trended slower compared to their previous
12Z cycles, more movement from the UKMET. For now, will go with
the greater ensemble support, and away from the quicker 00Z GFS.
Also, the 00Z GFS is now the fastest of the latest deterministic
guidance.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Otto