Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1244 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/00Z 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
00Z ECMWF along with support from the 06Z 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: Blend of the 12Z GFS/00Z UKMET and 00Z CMC
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 12Z NAM and 00Z ECMWF
maintain a closed low feature farther west back over western
AZ/southeast CA by Saturday evening, whereas the 12Z GFS, 00Z
UKMET and 00Z CMC favor a bit more advancement downstream toward
NM and possibly west TX. For now will lean toward the slightly
more progressive camp, given a better ensemble clustering away
from the NAM/ECMWF solutions. Thus, will prefer a blend of the 12Z
GFS, 00Z UKMET and 00Z CMC.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison