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Model Diagnostics Discussion
(Latest Discussion - Issued 0657Z Sep 26, 2018)
Version Selection
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Abbreviations and acronyms used in this product
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White

Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
257 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

00Z Model Evaluation...with Preferences and Forecast Confidence

...Overall Preference for the Entire CONUS...
Preference: Non-NAM blend
Confidence: Above average

---06Z UPDATE---
No change to the preliminary preference for WPC QPF. Slightly more
difference has emerged with precipitation along a secondary cold
front in the Great Lakes, with the ECMWF and UKMET wetter than the
GFS and CMC. The preference for the WPC QPF was to blend the two

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
500 mb forecasts at