Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1231 PM EDT Fri Sep 27 2019

Valid Sep 27/1200 UTC thru Oct 01/0000 UTC

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

12Z Final Model Evaluation with Preferences and Forecast Confidence
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...Overall Pattern Across the CONUS...
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Preference: General Model Blend
    Greatest weight on 00Z ECMWF and EC Ensemble Mean
Confidence: Above average

Model spread has continued to narrow for the forecast over the
next few days, as models come into better alignment with the
amplified synoptic pattern developing across the CONUS. Given that
the deterministic models are quite clustered and supported by a
majority of the ensemble distribution, a multi-model blend is the
preference for the short term portion of the forecast.

Greater weight is placed on the ECMWF and ECMWF Ensemble Mean,
particularly by Days 2 and 3. Most of the GEFS members and
operational GFS are consistently on the lower end of the forecast
heights ensemble distribution aloft. Lower heights, particularly
by the 72-96h forecast periods, is a bias in the GFS, so greater
weight is placed on the ECMWF to counteract that bias. The other
global models show slightly more amplification to the ridge over
the central and eastern U.S. as well. Nevertheless, the
differences between the models are still relatively small and the
GFS is included in the overall blend.


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

Lamers