Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
101 PM EDT Wed Mar 27 2019

Valid Mar 27/1200 UTC thru Mar 31/0000 UTC

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

12Z NAM/GFS Model Evaluation With Initial Preferences and
Confidence
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...Overall Pattern Across the CONUS...
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Preference: 12Z GFS/00Z ECMWF blend; favoring ECMWF
Confidence: Slightly above average

Models are in good general agreement with the decay of the closed
low off the West Coast and the interaction of southern stream
energy from that low with a trough approaching the north-central
CONUS from Canada Friday into Saturday. The degree of which these
systems phase or not over the central CONUS and the strength of
the southern stream energy are the biggest model differences
through 84 hours.

The 12Z GFS has slowed the southern stream wave which results in
more separation with the northern stream trough on Saturday which
still has the GFE feature less phasing of the two features with a
similar solution to the 00Z ECMWF. The 00Z UKMET is the most
phased with the farthest north surface low tracking across Midwest
Friday-Saturday. The strength of the southern stream trough is
strongest in the 12Z NAM and 00Z CMC which result in higher
magnitude QPF compared to the preferred GFS/ECMWF solutions.

There has been better consistency in the ECMWF forecasts the past
few model cycles and this agrees more with the ensemble spread as
well. A solution near the 00Z ECMWF is preferred with the 12Z GFS
close enough to warrant inclusion.


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

Jackson