Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
534 AM EST Sat Nov 09 2019
Valid Nov 09/0000 UTC thru Nov 12/1200 UTC
..See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
...00Z Model Evaluation with Final Preferences and Confidence...
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...Weak surface low tracking north of the Great Lakes today...
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Preference: General model blend
Confidence: Above Average
The guidance shows similarly with this system.
...Shortwave(s) shearing into the interior Northwest and joining
with an amplifying mid-level trough axis into the north-central
U.S. for Monday...
...Surface low in the vicinity of New England Tuesday morning...
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Preference: 00Z NAM, 00Z GFS, 00Z ECMWF blend
Confidence: Average
Ensemble has shown convergence over its past four 12/00Z cycles
but some timing and amplitude differences remain with the 500 mb
trough crossing the north-central U.S. and Great Lakes early next
week. The 00Z GFS is slightly more progressive with the 500 mb
trough, but flow downstream lacks a blocking ridge which may
support a more progressive track to the upper trough. The 00Z
ECMWF and 00Z NAM are more similar with a slower trough, NAM more
amplified, but the NAM's surface low near the New England coast
Tuesday morning is displaced slightly south/east of the centroid
of the latest ensemble scatter low plots. The 00Z ECMWF is
consistent with its previoius 12Z run and lies near the middle of
the latest scatter low plots. Meanwhile, the 00Z UKMET was weaker
with the surface low near the coast Tuesday morning and the 00Z
CMC (similar to the 12Z CMC) was slower with the mid-level trough
axis.
...Cold front nearing the Pacific Northwest on Tuesday...
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Preference: 00Z NAM/00Z GFS blend
Confidence: Average
Timing differences appear starting Monday morning as a cold front
approaches the Pacific Northwest. The 12Z UKMET is slowest while
the 12Z ECMWF is fastest with the related upper level trough. The
00Z NAM/00Z GFS appear to make up a reasonable compromise in the
middle of the latest spread.
...Closed low over northwestern Mexico...
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Preference: General model blend
Confidence: Average
Some minor timing differences exist with this feature with the 00Z
GFS/00Z UKMET fastest and 00Z CMC slowest. Only minor adjustments
were noted between the 00Z and 12Z ECMWF/UKMET/CMC. Ensemble means
are in the middle, and actually, the differences between the
deterministic guidance are small enough through Tuesday to support
a general model blend for the preference.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Otto