Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1248 AM EDT Fri Oct 26 2018

Valid Oct 26/0000 UTC thru Oct 29/1200 UTC

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

00Z Model Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: General model blend; more weight 12Z ECMWF
Confidence: Average

Despite some notable differences in the mass fields with the
deterministic models, particularly after 27/12Z (Saturday
morning), the model QPFs are fairly similar. Because of this, the
preference is to go with a general model blend and place more
weight on the model forecasts that seem most likely.

The largest differences occur with the amplitude of the trough in
the East by Sunday, with the 00Z GFS much flatter and less
amplified as compared to the other deterministic models. The 12Z
ECMWF, for instance, spreads QPF further south with a secondary
digging wave, while the 00Z GFS confines it mostly north of the
Ohio River. The ECMWF has much greater support from the 12Z
GEFS+ECMWF ensemble clusters, and thus greater weight was placed
on the ECMWF. However, the notable trend on the GFS has been to
the north over the past several model cycles; given the consistent
trend, the GFS was not eliminated from the preference.

Least weight in the model blend was placed on the 12Z CMC and 12Z
UKMET which continue to have higher mid-upper level vorticity
values further south (along the Gulf Coast) on Saturday as
compared to the GFS, ECMWF and NAM, with a weaker Great Lakes
trough extension, which leads to less phasing and weaker and
further east surface lows on the East Coast. The GFS and ECMWF
appear to have the most ensemble support at this time.


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

Lamers