Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1140 PM EST Wed Nov 14 2018

Valid Nov 15/0000 UTC thru Nov 18/1200 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: Blend of the 00z GFS/NAM, 12z ECMWF
Confidence: Slightly above average

A closed upper level low currently over the mid-MS River Valley
will open up as it lifts into the mid-Atlantic and Northeast
through Friday, becoming absorbed within the longwave trough over
the northern tier US. A secondary shortwave trough will push
through the Great Lakes region Friday before lifting off the
Northeast US Friday night. In general, there is a good model
agreement with this feature between the 00z NAM/GFS and the 12z
model cycle.

With respect to the East Coast low track, the 00z GFS/NAM are
fairly similar through about 24-36 hours, but differ once the low
crosses Cape Cod, where the GFS turns offshore sooner/faster
compared to the NAM which stays closer to the Maine coast. The 12z
ECMWF was a bit of compromise between these two solutions.

Beyond 60 hours to the end of the forecast period, more benign
weather will take shape over the CONUS with a western ridge and
much of the eastern troughing staying north of the Great Lakes. A
digging shortwave will push into the northern Rockies Saturday
into Sunday. The 00z NAM continues to show a different
configuration of a positively tilted trough (slower and a
different orientation) relative to all the other models, and given
its departure from the ensemble means, the preference was to place
less weight on the NAM in the West and later in the forecast
period, but overall across the CONUS, a blend of the 00z GFS/NAM
with the 12z ECMWF 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

Taylor