Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
236 AM EDT Mon Jul 01 2019

Valid Jul 01/0000 UTC thru Jul 04/1200 UTC

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

12Z Model Evaluation...with Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 00Z ECMWF, 00Z GFS
Confidence: Slightly below average

---06Z UPDATE---
No change to the preliminary preference. The UKMET in particular
continues to show greater ridging through much of the CONUS.

---PREVIOUS DISCUSSION---
Available models show a similar synoptic pattern, and general
agreement on major synoptic features. However, there are important
detail differences that have an impact on QPF, and model spread is
somewhat higher than in the past few days. Therefore, forecast
confidence is lower than in previous days.

The 12Z CMC and UKMET both show higher heights through much of the
CONUS, in particular the UKMET. These two models stand out
relative to the other deterministic models and ensemble means, but
there are some ensemble members that show similar degrees of
ridging. The CMC ensemble members are generally higher than the
ECMWF and GEFS across the board. With less support for these two
model mass field forecasts, they are excluded from the preference.

Meanwhile, the 00Z NAM is showing a faster progression of
shortwaves in the northern stream, particularly beyond 03.00Z
(Tuesday evening). Therefore, the preference is to lean toward a
blend of the ECMWF and GFS as they have greater ensemble support.
These two models still do show some differences, but they are
similar enough to comprise a model blend. One notable difference
is in the Northwest on Wednesday, as the GFS concentrates an upper
level low further north near Washington, while the ECMWF shows a
trough with the associated vorticity maximum situated in northern
California.


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

Lamers