Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
151 AM EST Wed Nov 14 2018

Valid Nov 14/0000 UTC thru Nov 17/1200 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 GFS/ECMWF
Confidence: Average

The latest model guidance shows a northern stream trough crossing
the Great Lakes and Northeast through Wednesday which will
gradually allow a rather strong area of high pressure to move
across these areas through Wednesday night and early Thursday.
Meanwhile, an upper level closed low over the southern Plains will
move east/northeast across the lower MS Valley on Wednesday and
then through portions of the OH/TN Valleys and adjacent areas of
the central Appalachians and Mid-Atlantic through Thursday and
Thursday night. As the system advances east with time, and high
pressure moves offshore of New England, the system will take on an
increasingly negative tilt, and it should advance progressively
through southern New England on Friday before advancing rapidly
toward Atlantic Canada. At the surface, a low pressure will
develop along a stalled frontal boundary and deepen as it moves up
the East Coast. This will bring an early season winter storm to
portions of the mid-MS and lower OH Valleys as well as far
interior portions of the Mid-Atlantic and Northeast.

Differences with the models are reflected especially with the
track of the mid and upper level low feature. The 00Z NAM tracks
its energy notably farther south across the TN Valley and central
Mid-Atlantic region compared to the global models which are
clustered on a track closer to the OH Valley and northern
Mid-Atlantic going through Thursday. The global models have
clustered on a more progressive solution, with the 00Z ECMWF
trending more progressive like the 00Z GFS, and the 00Z UKMET/CMC
also supporting a more progressive solution. The ECMWF has also
trended a bit north compared to its previous run and is overall
very close to the GFS solution. Timing differences at the surface
are modest with respect to the surface low, although the NAM is
perhaps a little slower than the model consensus.

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. By late in the period, a
new ridge axis is forecast to be situated just off the West Coast.
The NAM and UKMET are out of tolerance with the GFS, CMC and ECMWF
solutions regarding the second shortwave and associated surface
wave evolution by the end of the period as they tend to favor a
relatively stronger surface wave dropping across the Plains and
toward the Midwest. Better ensemble support tends to reside with
the GFS and ECMWF.

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


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

Orrison