Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
250 AM EDT Wed Sep 26 2018

Valid Sep 26/0000 UTC thru Sep 29/1200 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: Non-NAM blend
Confidence: Above average

Models show a relatively static pattern through the remainder of
the week, with a rex block off the West Coast, a broad trough
across the northern tier of states (extending south into the
Plains), and a ridge along the East Coast. Shortwaves digging
south from Canada will help reinforce the longwave trough and
affect some small changes, but the consistent pattern should lead
to a high degree of predictability. And thus, it is not surprising
to see good model agreement overall. The biggest difference among
the deterministic model QPFs is from the NAM on Day 3 (Friday and
Friday Night), with a faster progression over the Southeast. It
showed much of the rainfall offshore over the Gulf of Mexico, in
contrast to the other models. Therefore, the preference was to
exclude the NAM. Otherwise, model QPF agreement is good enough
that a general blend was preferred.


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

Lamers