Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1135 AM EST Fri Dec 20 2019
Valid Dec 20/1200 UTC thru Dec 24/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation with Preference and Forecast Confidence
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...Overall Pattern Across the CONUS...
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Preference: 12Z GFS, 00Z ECMWF, 06Z GEFS, and 00Z ECENS mean
Confidence: Average
The initial 12Z guidance shows a continued slowing trend with the
large scale system impacting the western U.S. through this
weekend, with the 00Z UKMET noticeably slower compared to the rest
of the guidance and is largely considered an outlier. The timing
between the GFS/ECMWF and the CMC to some degree are fairly
similar and offer a reasonable blend for the western U.S. system.
The closed mid level low that will track from the southern Plains
to the northern Florida coast early next week continues to show
some decent model agreement. The GFS and NAM are a bit faster than
the non-NCEP guidance and while the UKMET is slower initially
(through 60 hours) it ends being near the model consensus at 500
mb. At the surface, the differences are more significant. The CMC
offers a faster and more eastward low (off SC coast by 23/00Z)
while the other guidance has trended slower and further west
(though not to the degree the 00Z UKMET suggests). A blend of the
12Z GFS and 00Z ECMWF with components of their ensemble means is
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