Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1243 AM EDT Fri Oct 11 2019

Valid Oct 11/0000 UTC thru Oct 14/1200 UTC

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

00Z Initial Model Evaluation with latest Preferences and Confidence
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...Deep closed low near the 40N/70W benchmark...
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Preference: General model blend
Confidence: Above average

The nor'easter situated about 100 miles southeast of the 40N/70W
benchmark has generally leveled off in intensity and is expected
to remain nearly stationary through most of Friday before tracking
towards the east-northwest and gradually weakens and becomes an
open wave.  This storm is currently blocked by a ridge axis over
eastern Canada and part of a Rex block pattern.  By Saturday
morning, the ridge moves out of the way and the broad circulation
around the big central U.S. low begins to propel the oceanic storm
eastward.  There are only minor differences in timing of the
eastward track, with the GFS and GEFS mean slightly faster and the
CMC slightly slower.  However, they are close enough to merit a
general model blend.


...Deep Plains/Upper Midwest Cyclone...
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Preference: General model blend
Confidence: Above average

An impressive upper level trough and closed low over the
north-central U.S. is supporting a rapidly developing surface low
that will track across northern Minnesota to southwestern Ontario
by Friday night, before making a slow cyclonic loop and then
eventually lifting towards the northeast while weakening.  This
will be accompanied by a pronounced cold front crossing the
Midwest and extending southward to the Gulf Coast, along with
potentially record snowfall for parts of the Dakotas and
northwestern Minnesota.  The models remain in very good agreement
with this large scale storm system through the forecast period
with only minor differences in timing and placement.


...Western U.S....
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Preference: GFS/ECMWF compromise
Confidence: Above average

The next feature of interest to affect the western U.S. will be a
progressive upper level trough that should reach the West Coast by
12Z Sunday, with a frontal boundary reaching the northern Rockies
by Monday morning.  The NAM appears more amplified than the other
guidance, whilst the CMC flatter and too progressive.  Both the
ECMWF and GFS appear to fit the pattern well and a blend of these
two models should work well as a starting point.


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

Orrison