Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1224 AM EDT Sun Apr 14 2019

Valid Apr 14/0000 UTC thru Apr 17/1200 UTC

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

00Z NAM/GFS Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of 00Z GFS/12Z ECMWF
Confidence: Slightly above average

There are two main features of interest across the CONUS for this
time period. The first is the long wave trough and surface low
tracking from the Mid MS Valley across New England to Newfoundland
by 16/12Z. The 00Z GFS is faster than the consensus through the
first 12 hours of the forecast, but  comes into better agreement
with the pack as the surface low crosses northern New England
before 15/12Z. The 12Z ECMWF appears to attempt a secondary
development over southern NH with this feature, before it rejoins
the consensus over Nova Scotia and Newfoundland after 15/12Z.  For
this feature, a general model consensus should suffice, even with
the timing issues in the 00Z GFS early in the forecast.

The second feature is the long wave trough coming ashore over the
Pacific Northwest near 16/00Z. At that time, the 00Z NAM/GFS are
close to the consensus with position and strength of the trough.
After that time, the 00Z NAM digs into the base of the trough over
NM faster than the consensus, while the 12Z UKMET appears to close
off the mid  level system too quickly over the Four Corners
region, as it drives the short wave into the base of the trough
much sooner than other operational or ensemble guidance. Based on
the above, a blend of the 00Z GFS/12Z ECMWF is preferred with this
feature, which as the support of its respective ensemble means.


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

Hayes