Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
319 PM EDT Thu Nov 01 2018

Valid Nov 01/1200 UTC thru Nov 05/0000 UTC

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

12Z Model Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 12Z GFS and 12Z ECMWF
Confidence: Slightly Above Average

The models generally agree on the large scale with the details of
the longwave trough amplifying into the eastern U.S. over the next
36 hours before then then pivoting rapidly northeast in a
negatively tilted fashion across the Mid-Atlantic and Northeast.
The 12Z CMC/NAM solutions are a little weaker than the 12Z
GFS/UKMET/ECMWF solutions with respect to the depth of the trough
and associated surface low that exits the Ohio Valley and crosses
the Northeast. The NAM is also a bit slower than the global
models. The preference will be to lean toward the stronger
consensus led by the GFS/ECMWF solutions with this system.

A new upper trough and associated surface low will then drop
southeast down across the central Plains later Saturday and
Sunday, and then lift northeast up toward the upper Midwest and
upper Great Lakes region by Sunday night. The 12Z NAM ends up
being faster with the low track advancing north across the
Midwest, with the 12Z CMC/UKMET solutions the slowest. The 12Z GFS
and 12Z ECMWF are clustered in between camps, and are well
supported by their ensemble means. Elsewhere, a fast-moving
shortwave will cross the Pacific Northwest by late Sunday and
Sunday night. The 12Z CMC/UKMET solutions are a little more
sheared/flatter with this system compared to the 12Z NAM/GFS/ECMWF
guidance.

Based on the latest model clustering, trends and ensemble spread,
a blend of the 12Z GFS and 12Z ECMWF will be preferred.

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

Orrison