Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
249 AM EDT Sat Sep 22 2018

Valid Sep 22/0000 UTC thru Sep 25/1200 UTC

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

00Z Model Evaluation...with Preferences and Forecast Confidence
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...Overall preference for the entire CONUS...
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Preference: Blend of 00Z ECMWF, 00Z UKMET, 00Z GEFS Mean
Confidence: Average

Models are in fairly good agreement through the weekend, but begin
to show increasing differences by Sunday Night and into Monday.
The normalized standard deviation of the 500mb heights on the
ECMWF Ensemble (12Z cycle) was generally above 1 across much of
the CONUS by Monday, indicating greater variance than the last
30-day average. Therefore, confidence in the forecast is a bit
lower toward the end of the Day 2 period and into the Day 3 period.

The 00Z NAM and 00Z CMC show greater differences from the overall
consensus, particularly with the strength of the wave lifting into
the Mid Mississippi Valley on Monday, and the amplitude of the
evolving trough in the High Plains around the same time. The 00Z
GFS showed greater differences with its QPF in a variety of places
around the CONUS. Therefore, the preference was to lean toward a
blend of the ECMWF, UKMET, and GEFS Mean, and in particular toward
the more consistent distribution of QPF in the Ohio Valley from
the UKMET over the past several model cycles.


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

Lamers