Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
236 AM EDT Fri May 31 2019

Valid May 31/0000 UTC thru Jun 03/1200 UTC

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

00Z Model Evaluation Including Preferences and Forecast Confidence
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...Overall Pattern Across the CONUS...
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Preference: Non-CMC blend
Confidence: Average

---06Z UPDATE---
No significant change to the preliminary preference. The ECMWF did
put more QPF in the southern Plains than the previous run, and has
generally converged to the other models.

---PREVIOUS DISCUSSION---
Over the next few days, deterministic model mass fields are in
relatively good agreement across the country and their QPF
patterns are fairly similar. The greatest amount of spread
continues to be with a broad trough pushing from the Midwest to
the Mid Atlantic today, and with the trough amplifying into the
Great Lakes later in the weekend.

Nevertheless, the most notable QPF differences tended to be in the
Plains and West with the 12Z ECMWF. In general, the ECMWF seemed
too dry in the West given abundant instability, and was certainly
drier than other models. In Kansas and Oklahoma on Sunday and
Sunday Night, the ECMWF had far less QPF than the other models.
However, the ECMWF was generally in agreement with the GFS in
placing an instability gradient in this area with at least
moderate instability to the south over Texas and most of Oklahoma.
Given the position of the northern edge of the instability pool,
convection would tend to be favored where the ECMWF is much drier.
For these reasons, less weight was placed on the ECMWF overall.

However, in the Great Lakes and Northeast, less weight was placed
on the 00Z GFS. This continued a trend of generally being lower
with heights in the eastern Great Lakes and interior Northeast
than the other models, as it digs the mid-upper level vorticity
maximum further south. This was also further south than most of
the ensemble members, so it seems less likely at this time.

The 12Z CMC was excluded from the preference, as it was showing
more notable differences in the southern half of the CONUS. By
Sunday, its position of the trough in the Southwest was further to
the east than just about every ensemble member, while the
downstream ridge over the southern Plains was less amplified than
every ensemble member.


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

Lamers