Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1144 PM EST Sat Nov 09 2019
Valid Nov 10/0000 UTC thru Nov 13/1200 UTC
..See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
...00Z NAM/GFS Evaluation with Preliminary Preferences and
Confidence...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...Amplifying mid-level trough axis into the north-central U.S.
for Monday...
...Surface low in the vicinity of New England Tuesday morning...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00Z NAM, 00Z GFS, 12Z ECMWF, 12Z ECMWF mean blend
Confidence: Average
There is good agreement with the upper trough amplitude and timing
as it nears the Great Lakes region with minor differences showing
up after Tuesday morning. The 12Z UKMET is flatter and faster with
the shortwave, resulting in an eastward displaced surface low
early Tuesday. Meanwhile, the 12Z CMC becomes slightly
slower/deeper with the upper trough placement resulting in a
surface low displaced to the south a bit of the agreeable 00Z NAM,
00Z GFS and 12Z ECMWF.
The good agreement with the surface low among the 00Z NAM/00Z
GFS/12Z ECMWF is broken up by the 18Z and 12Z GEFS/12Z ECMWF mean
surface lows displaced slightly south and east of the
deterministic consensus. Therefore, blending the NAM/GFS/ECMWF
with the 12Z ECMWF mean is preferred to account for the
displacement of the means relative to the deterministic agreement.
...Cold front nearing the Pacific Northwest on Tuesday...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00Z NAM, 00Z GFS and 12Z ECMWF blend
Confidence: Slightly above average
Cold frontal timing into the Pacific Northwest is good with the
latest guidance. Differences show up with the corresponding
shortwave downstream into the north-central U.S. The 12Z CMC
stands out with a stronger/faster shortwave while the 12Z UKMET is
weaker by 12Z/13. A blend of the 00Z NAM, 12Z ECMWF and 00Z GFS is
reasonable given better agreement to the ensemble means.
...Closed low over northwestern Mexico...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00Z NAM, 00Z GFS and 12Z ECMWF blend
Confidence: Average
Ensemble spread is modest by 12Z/13 but the 12Z CMC is slower and
12Z UKMET faster than the middle of the spread. The middle of the
spread, tighter clustering and ensemble means supports a blend of
the 00Z NAM, 00Z GFS and 12Z ECMWF.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Otto