Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1232 PM EDT Fri Oct 11 2019

Valid Oct 11/1200 UTC thru Oct 15/0000 UTC

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

12Z Model Evaluation with latest Preferences and Confidence
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...Subtropical Storm Melissa...
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Preference: General model blend
Confidence: Above average

Subtropical storm Melissa, located 190 miles south of Nantucket,
MA as of 15Z, is expected to weaken and drift south through
tonight and then begin to advance east and out to sea through the
weekend which will lessen the coastal impacts to New England and
the Mid-Atlantic with time. The guidance shows reasonably strong
agreement with the evolution of this system, and so a general
model blend will be preferred.


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

A very strong deep layer cyclone over the north-central U.S. is
forecast to weaken this weaken and move east across the upper
Great Lakes and adjacent areas of Ontario. Meanwhile, a cold front
will cross the OH/TN Valleys and reach the East Seaboard by
Saturday night before losing its identity and dissipating on
Sunday. A secondary cold front associated with the storm system
will develop and cross the Midwest on Sunday and then move toward
the East Coast on Monday. A general model blend will be preferred
with the evolution of the deep layer cyclone and the associated
front.


...Western U.S....
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Preference: Non-NAM blend...over the Southwest
            General model blend...remainder of Western U.S.
Confidence: Above average

The next feature of interest to affect the western U.S. will be a
progressive upper-level trough and associated cold front that
should reach the West Coast by early Sunday, and then advance
inland across the Intermountain Region on Monday. By late Monday,
the height falls will be starting to spill out across the High
Plains and this will result in lee-side cyclogenesis over the
central Plains. Given the level of good model clustering, a
general model blend will be preferred with this system for now.

Meanwhile, the guidance is also advertising the arrival of a
southern stream shortwave that will be digging into the Southwest
by later Monday. The 12Z NAM is a bit stronger than the global
model suite with this feature. A non-NAM blend at this time.


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

Orrison