Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
308 AM EDT Tue May 21 2019

Valid May 21/0000 UTC thru May 24/1200 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

00Z Model Evaluation with Final Preferences/Confidence...
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...Closed mid-level low over the central U.S. today and eventually
reaching the Northeast on Friday...
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Preference: 00Z ECMWF/UKMET blend
Confidence: Slightly above average

The 00z NAM stands out from the remaining model consensus rather
early with less separation between the closed low moving north
through the Great Plains and a second closed low over the western
U.S. This results in the 00Z NAM having a slower progression to
the east across the Great Lakes region. On the other side, the 00Z
GFS appears a bit too fast, outpacing the latest ensemble
clustering which has not trended faster over its past 4 cycles.
The 00Z ECMWF/UKMET match well within the middle of the latest
deterministic/ensemble clustering and show favor with the 12Z/20
GFS which was preferred day shift Monday.


...Vigorous Pacific closed low digging into the West
Tuesday/Wednesday...
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Preference: non 00Z UKMET blend
Confidence: Average

There is good agreement with this system through Wednesday night
regarding strength and timing. Some differences begin to show up
on Thursday though, mainly with the 00Z UKMET having the closed
low center displaced west of the centroid of the remaining
deterministic guidance and ensemble spaghetti charts. Outside of
the 00Z UKMET, differences among the remaining deterministic
guidance is relatively minor.

Model trends at www.wpc.noaa.gov/html/model2.html
500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml

Otto