Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1208 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 NAM/GFS Evaluation with Preliminary 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, 12Z 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 12Z
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 12Z ECMWF is near
the middle of the latest scatter low plots. Meanwhile, the 12Z
UKMET was a bit flatter with the upper trough earlier in the
period across the central U.S. and the 12Z CMC is the slowest/most
amplified with the upper trough.
...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/12Z UKMET fastest and 12Z CMC slowest. 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