Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
259 AM EDT Tue Jul 02 2019

Valid Jul 02/0000 UTC thru Jul 05/1200 UTC

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

12Z Model Evaluation...with Final Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: Non-UKMET blend; greatest weight on 12Z ECMWF
Confidence: Slightly below average

---06Z UPDATE---
No change to the preliminary preference. The 00Z UKMET continues
to show generally higher heights through much of the CONUS, and
the 00Z ECMWF remained relatively consistent in its depiction of
mass fields.

---PREVIOUS DISCUSSION---
In addition to the typical uncertainty associated with convection
during the warm season, the forecast over the next several days
also has slightly more uncertainty related to QPF details with
greater model spread. The model spread is most notable with the
timing and amplitude of waves, particularly in the northern stream
as they traverse the northern portions of the CONUS. Therefore,
forecast confidence is listed as slightly below average.

The 12Z UKMET was not included in the model preference this
evening, but the 00Z run will be monitored for better agreement
with the other deterministic models. The UKMET continues to remain
on the more amplified fringe of ensemble spread with the amplitude
of ridging over much of the central and eastern CONUS, and with a
ridge in the Northwest on Thursday Night, just downstream of a
trough approaching Washington. Given the lower ensemble support,
the UKMET was not included in the preliminary preference.

Otherwise, the remaining deterministic models represent reasonable
possibilities. The most weight was applied to the 12Z ECMWF as it
has more consistent ensemble support. Less weight was applied to
the 00Z GFS and 00Z NAM; those two models tend to be on the fast
end of ensemble spread with respect to speed of shortwaves, and
they also show much more significant troughing over the Ohio
Valley by Thursday and Thursday Night. The only models that show
this are the NAM, GFS and GEFS members, while the remaining
deterministic models show a weaker trough and/or a flatter heights
pattern through the Great Lakes and Ohio Valley. Given weaker
ensemble support for that idea, less weight was placed on those
models.


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

Lamers