Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
139 PM EST Tue Nov 06 2018

Valid Nov 06/1200 UTC thru Nov 10/0000 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 12Z GFS, 0012Z ECMWF
Confidence: Average

---18Z UPDATE---
No change to the preliminary preferences. The 12Z ECMWF is
reasonably consistent with its prior run and the 12Z GFS as well.

---PREVIOUS DISCUSSION---
A broad trough over the northern half of the CONUS will get
reinforced by a sharply digging shortwave into the Northern Plains
by Friday. The most model spread exists with position of the
resulting trough axis (west-to-east) and strength of the primary
vorticity maximum. The 00Z CMC is much flatter with the wave
pattern across the CONUS overall, and has a notable eastward
displacement of the trough axis by Friday. This was basically east
of all the GEFS+ECMWF ensemble members, and thus it is not
included in the preference. Meanwhile, the 00Z UKMET and 12Z NAM
have a stronger mid-upper level vorticity maximum, more amplitude
to the trough, and a slight westward displacement of the trough
axis. Their heights aloft are higher than most GEFS+ECMWF ensemble
members in the eastern Great Lakes and interior Northeast, and are
lower than the median ensemble heights in the Upper Midwest and
Missouri Valley. The 12Z NAM in particular is much stronger than
other models, and closes off a 500mb low by the end of the period.
The preference, therefore, is to lean toward a 12Z GFS and 00Z
ECMWF blend; those two models are closest to the tightest
clustering of ensemble forecasts. Across the Gulf Coast, slightly
more weight was given to the GFS for the WPC QPF, as it has its
rainfall focused further south and mostly along the coast. This
seems more likely given the expected position of the front and
reduced instability further inland to the north of the front
(ECMWF has heavier precip further inland).


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

Lamers