Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
237 PM EDT Fri Mar 15 2019
Valid Mar 15/1200 UTC thru Mar 19/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...Shortwave energy over the northern Plains/Midwest...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Blend of the 12Z GFS and 00Z ECMWF
Confidence: Average
In the wake of the exiting deep cyclone over the Midwest and Great
Lakes will be an intrusion of northern stream shortwaves from
southern Canada which will cross the northern Plains and Midwest
through the weekend. The 12Z NAM is a bit sharper with the
shortwave impulses and is overall a bit more out of phase with the
global models. The 12Z UKMET/CMC solutions also show some evidence
of being at least a bit too sharp with energy late in the period
dropping down across southern Canada and toward the Upper Midwest.
However, the 12Z ECMWF did trend toward the UKMET/CMC camp with a
bit stronger energy over southern Canada. The latest ensemble
means, including the 12Z GEFS mean and 00Z ECENS mean, still do
not favor anything quite as sharp as the non-NCEP models. Based on
the degree of uncertainty, the preference will be to keep the
prior recommendation with a blend of the 12Z GFS and 00Z ECMWF.
...Weak upper trough/closed low moving into the Southwest...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Non-GFS blend
Confidence: Slightly above average
A weak upper trough and associated closed low will move into the
Southwest through the weekend and should begin to dampen out and
shear east toward the southern High Plains by Monday. The 12Z GFS
appears to be a bit of a weaker outlier compared to the remaining
guidance by the end of the period. A non-GFS blend will now be
preferred given that the 12Z CMC/UKMET solutions trended a bit
slower and toward the well clustered 12Z NAM/ECMWF solutions.
...Shortwave over the northern Rockies by Sun...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Blend of the 12Z GFS/CMC/ECMWF
Confidence: Slightly above average
The 12Z NAM and 12Z UKMET are relatively stronger outliers with
the shortwave rounding the mean layer ridge along the West Coast
on Sunday and dropping down over the northern Rockies. The
remaining guidance as per the 12Z GFS, 12Z CMC and 12Z ECMWF is a
tad weaker and tends to have better ensemble support, and thus the
preference will be toward the weaker consensus.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison