Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1220 AM EDT Sun Apr 21 2019

Valid Apr 21/0000 UTC thru Apr 24/1200 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: 00Z GFS, 12Z ECMWF, 12Z UKMET
            Slightly less weight on the GFS
Confidence: Above average

Model spread surrounding the two troughs on either coast at the
moment, and their eventual evolution, has generally narrowed over
the past couple model cycles. Overall, deterministic models are in
reasonably good agreement.

There are a couple exceptions. The 00Z NAM shows considerably
stronger shortwaves progressing through the northern stream along
the Canadian border, leading to much more amplified (and slower)
troughs in the Great Lakes and Northeast in the Monday-Tuesday
time frame. The 12Z CMC is likewise slower with the progression of
the troughs, despite a similar amplitude to the other models.
Neither of these models are included in the preference.

Otherwise, the 00Z GFS and 12Z ECMWF and UKMET represent a
consensus forecast that is well supported by available ensembles.
Slightly less weight is placed on the 00Z GFS in the northern
stream (and particularly in the Northeast). The GFS shows a faster
ejection of the trough away from the Northeast, and shows less QPF
for Day 2 (even compared to the FV3 and GEFS Mean).


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

Lamers