Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1210 AM EDT Sat Oct 19 2019

Valid Oct 19/0000 UTC thru Oct 22/1200 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

00Z Model Evaluation with Preferences and Confidence
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Northern stream shortwaves entering the West ejecting into
Northern and Southern Plains...
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Preference: General model blend through 48 hours;
            12Z ECMWF/12Z UKMET and ECENS/GEFS means after
Confidence: Average

Latest water vapor imagery and 500 mb heights showed troughing
across the Rockies about to move into the Plains states tonight
while upstream, a stronger, more compact shortwave along the
cyclonic rotor of a very strong/broad Pacific jet, will begin to
approach the Pacific Northwest coast by morning. The leading
trough is well represented by the most recent model guidance and
can be handled with a general model blend through 48 hours.

The stronger shortwave upstream is likely to become negatively
tilted as it crosses the central/northern Rockies and could close
off as it moves into the central/northern Plains states. The GFS
remains the fastest solution and therefore closes off 6-12 hours
ahead of the other guidance. It is also further north compared to
the non-NCEP guidance (CMC is the furthest south). The 12Z CMC
becomes a bit too amplified by the end of the forecast period,
such that it probably should be tossed out for the mass fields.
The ECMWF is a decent compromise and follows along the model
consensus through the 3 days. The 18Z GEFS

Vortical stretching combined with the favorable upper level
pattern will induce rapid surface cyclogenesis that will deepen as
it approaches the Upper Mississippi River Valley. The NAM/GFS are
on the northern end of the model envelope while the CMC is the
furthest south. The ECMWF/UKMET lie in between and agree with the
most recent ECENS/GEFS means as well. With that in mind, will
prefer the 12Z ECMWF/UKMET along with the 12Z ECENS and 18Z GEFS
means, especially beyond 48 hours.


Tropical Storm Nestor
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Preference: See latest NHC advisory
Best Proxy: 00Z GFS through 20.00Z; 12Z ECMWF/UKMET after

Fairly tight clustering and above average agreement with the
initialization of the incoming 00Z guidance for T.S. Nester as it
turns north/northeast toward the FL Panhandle. Through 20.00Z
there is little spread with the low track, though the latest (00Z)
GFS does have the best proxy to the official NHC advisory track
from 03Z. Beyond that time-frame, the system is expected to move
off the NC coast between 20.12Z and 21.00Z, and model guidance
does begin to diverge. The 00Z NAM is the generally west of the
official track through the next 2-2.5 days and is considered
mostly an outlier. The rest of the guidance is in reasonable
agreement, though the ECMWF/UKMET seem to offer the best proxies
to the official track and have the best continuity from previous
forecasts as well.


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

Taylor