Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
140 AM EST Tue Nov 13 2018

Valid Nov 13/0000 UTC thru Nov 16/1200 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: Blend of the 00Z NAM/GFS/ECMWF
Confidence: Average

The synoptic pattern currently features an upper level ridge over
the western US with downstream troughing across the central US. A
couple of shortwave troughs are embedded in the flow, with one
digging across the northern tier of the U.S. and southern Canada
while another is amplifying down across the southern High Plains.

Over the next 24 to 36 hours, the southern stream shortwave will
slow and become further detached/removed from the northern stream
energy/flow and evolve into a closed low over north Texas, which
is where model uncertainty begins to increase. The 00Z UKMET is
considered an outlier, as it is considerably faster than the rest
of the global deterministic models with the progression of the
closed low downstream across the lower MS/TN Valleys and toward
the central Appalachians and Mid-Atlantic region through Thursday
and Friday. The 00Z NAM/CMC/ECMWF solutions are all clustered
toward the slow side of the model spread with the 00Z GFS in
between camps. By comparison, there is better model agreement with
the track and strength of the surface low that forms near the
Southeast coastline and then lifts northeast up along the East
Coast Thursday and Friday. The NAM is likely a bit too weak with
its low, but the UKMET appears too strong and too progressive. The
latest ensemble means are generally split with the details of the
upper trough/closed low evolution, with the GEFS favoring the GFS
and the ECENS favoring the ECMWF.

Meanwhile, the models all support the deep layer ridge over the
West breaking down a bit and allowing a pair of northern stream
shortwaves to drop down near the Pacific Northwest and through the
northern Plains and upper Midwest going through Thursday and
Friday. The first shortwave will drive a surface low across
southern Canada along with a cold front, with the second shortwave
dropping a little farther south down across the northern High
Plains which will allow a new surface low and the same the same
cold front to drop across this region. Better clustering resides
with the NAM/GFS and ECMWF with these features.

Based on the latest model clustering and trends across the CONUS,
the overall preference is weighted toward a blend of the 00Z
NAM/GFS/ECMWF solutions.


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

Orrison