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Model Diagnostics Discussion
(Caution: Version displayed is not the latest version. - Issued 0638Z Jul 13, 2018)
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Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
238 AM EDT Fri Jul 13 2018

Valid Jul 13/0000 UTC thru Jul 16/1200 UTC

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

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

...Overall Model Analysis for the CONUS...

Overall Preference: Non-NAM blend
General Confidence: Slightly above average

---06Z UPDATE---
No change to the preliminary preference or reasoning.

The weak flow pattern persists across the CONUS over the next
several days, with 500mb heights generally varying by less than
60m across the country. Differences in model mass fields continue
to be relatively minor, and thus a general model blend is
preferred. This will help account for the inherent uncertainty
given the convective nature of most of the rain.

One exception: the 00Z NAM was excluded from the preference. It
develops a much stronger wave over the Upper Midwest this weekend,
likely the result of some convective feedback. This results in a
concentrated area of much higher QPF than other models, and its
other mass fields are influenced as well. For instance, the 850mb
LLJ strength in the inflow region is about twice as strong as
other models.

Model trends at
500 mb forecasts at