Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1154 AM EST Mon Nov 12 2018

Valid Nov 12/1200 UTC thru Nov 16/0000 UTC

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

12Z Model Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 12Z GFS/NAM and 00Z ECMWF
Confidence: Slightly above 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, one moving
across the northern tier and southern Canada while another is
slowly drifting through the lower Rockies around CO/NM. A plume of
subtropical moisture exists ahead of that, bringing widespread
precipitation to much of the southeast US. At the surface, an area
of low pressure was analyzed near the Texas Gulf Coast with a
quasi-stationary boundary hugging the coastline from TX/LA to the
FL/AL line.

Over the next few days, the the southern stream shortwave will
continue to slow and become further detached/removed from its
parent northern stream energy. It eventually closes off by
Wednesday morning over north Texas, which is where model
uncertainty begins to increase. The 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. The
12z GFS is faster with the closed low position compared to the
ECMWF, but the spread has been decreasing in the past few model
cycles. The surface low over the Gulf Coast is expected to
redevelop and strengthen off the mid-Atlantic coast tonight into
Tuesday. There is better model agreement with its track and
strength now as it tracks up the coastline, though the ECMWF (and
ECENS low clusters) are a bit to the west compared to the GFS (and
its GEFS clusters), which take the low more off the coast. The 12z
NAM low track lies in between of these two solutions. Meanwhile,
the 00z CMC seems too low compared to the consensus.

Toward the end of the forecast period, another area of low
pressure is likely to form across the northeast Gulf of Mexico and
eventually track up the eastern seaboard. There is larger model
uncertainty with its track beyond the current forecast period.

The overall preference is weighted toward a blend of the 12Z
GFS/NAM and 00z ECMWF. Confidence in particular across the
southern and eastern U.S. by Thursday is below average considering
the degree of spread among the deterministic and ensemble
guidance. Elsewhere, confidence is generally above average.

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

Taylor