Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
202 AM EST Sat Nov 24 2018

Valid Nov 24/0000 UTC thru Nov 27/1200 UTC

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

00Z Model Evaluation...with Final Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall pattern across the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00Z GFS/00Z UKMET/00Z CMC/12Z ECMWF blend (see details
below)
Confidence: Average

...07Z update...

Across the Northeast, the 00Z CMC came in a little closer to the
previous preferred consensus but it remains displaced enough with
the surface low to exclude it from being preferred Saturday night.

Across the central U.S., trends in the 00Z ECMWF/UKMET/CMC were
mixed with the 500 mb trough timing but with the surface low
track, the idea was to move south. The 00Z ECMWF, however, trended
slower and is now on the slow/far western edge of the latest
ensemble spread and is not preferred, certainly when compared with
the previous 12Z ECMWF. Otherwise, the 00Z UKMET/CMC continue to
split the differences toward the middle and perhaps a tad on the
slower side compared to the ensemble means.

No significant changes were noted out West.

...previous discussion follows...

Two well defined shortwave troughs will swing through the central
and eastern U.S. through early next week with surface lows
wrapping up along the Northeast Coast (Saturday night into Sunday)
and from the central Plains to Great Lakes (Sunday into Monday).
The pattern across the lower 48 will adjust by Monday to having a
large closed low centered over the Great Lakes region with broad
upper troughing approaching the Pacific Northwest and ridging over
the Intermountain West between the two troughs.

...East...
In the East, a blend of the 00Z NAM, 00Z GFS and 12Z ECMWF fit the
preferred solution nearest to the agreeable ensemble means and
fitting trends concerning the surface low Saturday night into
Sunday. The 12Z UKMET ends up on the slower/western side of the
guidance by Monday morning and the 12Z CMC is a bit of an outlier
with its 500 mb / surface pattern off of the East Coast.

...Central to Eastern U.S...
Across the central U.S., ensembles have trended a little faster
compared to yesterday valid 00Z/26 when looking at the 546 dam
height contour over the Midwest. Looking at the surface, GEFS
members continue to be faster than the ECMWF members. Outside of
the 00Z NAM which has a more open trough at 500 mb and ends up
faster than the remaining deterministic/ensemble consensus, there
is fair agreement between the 00Z GFS, 12Z ECMWF/UKMET/CMC with
the 12Z ECMWF south of the 00Z GFS and the 12Z UKMET/CMC in the
middle. A blend of the non 00Z NAM models, but perhaps slightly
faster to account for the ensemble means being a bit faster is
preferred.

...West...
Across the western U.S., model agreement is fairly good, but the
12Z ECMWF is slower with shortwave energy nearing the Northwest
Monday evening. A general model blend with a little less weight on
the 12Z ECMWF is preferred.

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

Otto