Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
244 PM EDT Wed Mar 13 2019
Valid Mar 13/1200 UTC thru Mar 17/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Preferences and Confidence
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...Powerful deep closed low impacting the Plains/Midwest...
...Secondary shortwave digging across the Great Lakes...
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Preference: General model blend...led by the 12Z GFS/ECMWF
Confidence: Above average
The models show very good agreement in taking the deep layer
closed low off to northeast across the central Plains through
tonight and then across the Upper Midwest through Thursday. This
energy will then eject across the Great Lakes and southeast
Ontario by Friday as a trailing cold front sweeps through the
eastern U.S. and then offshore the East Coast by Saturday. In
behind the departing Midwest storm system will be a new northern
stream trough for which the 12Z NAM is a bit stronger than the
model consensus. While the large scale differences are quite
modest with respect to the exiting surface low/height falls, and
with the timing of the surface cold front sweeping across the
East, the overall better model clustering is with the 12Z GFS and
12Z ECMWF along with support from the 12Z GEFS mean and 00Z ECENS
mean. Will prefer a general model blend weighted toward the
GFS/ECMWF solutions as a result.
...Weak upper trough reaching the West Coast Thurs night...
...Digging into the Southwest on Fri/Sat...
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Preference: Non-GFS blend
Confidence: Average
A weak upper trough will approach the West Coast by Thursday night
and then separate out from the westerlies and dig into the
Southwest on Friday and Saturday. The guidance agrees in
developing a weak closed low feature over AZ by early Saturday,
and then differences appear with how quickly this energy advances
east toward the southern High Plains. The non-NCEP models led by
the 12Z UKMET/12Z CMC and 12Z UKMET have all clustered together on
a slower evolution of the closed low as ridging develops farther
north over the Great Basin. The 12Z NAM agrees with the non-NCEP
cluster, and it would appear at this point that the 12Z GFS is a
bit of a progressive outlier. The 12Z GEFS mean trended slower and
is farther west with the troughing/closed low by the end of the
period. The 00Z ECENS mean already strongly supports the slower
camp, and so based on the latest model trends and clustering, a
non-GFS consensus will be preferred.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison