Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
231 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 Model Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of 00Z GFS/00Z 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 00Z ECMWF appears to have backed off on the
idea of a secondary development over southern NH with this
feature, and remains close to 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 00Z UKMET continues 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
sooner than other operational or ensemble guidance. While the 00Z
ECMWF is a tad faster with the mid level system over CO/NM, it
does not appear as though the changes merit excluding it from the
blend here.

Based on the above, a blend of the 00Z GFS/00Z 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