Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
245 AM EST Sat Feb 01 2020
Valid Feb 01/0000 UTC thru Feb 04/1200 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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...Evolution of Trough over Eastern Half of the U.S. through
Sunday...
...Coastal low tracking north offshore of New England late
Saturday...
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Preference: General model blend
Confidence: Slightly above average
Models were still making some run to run shifts in terms of how
much energy will be part of the northern stream portion of the
mid-level trough that affects parts of the Northeast later this
coming night. Downstream of the trough axis, surface cyclogenesis
is expected to occur off of the Mid-Atlantic or New England coast
later today. The GFS was still a bit stronger than the UKMET
while the Canadian was more amplified resulting in the base of its
trough being deeper and more southerly. Thinking is that a blend
of the 01/00Z GFS and NAM will work with the 01/00Z ECMWF will
work to minimize some of these differences and maintaining a
middle ground.
Regarding the offshore surface low, there is good agreement with
track until the low is offshore of Nova Scotia, with a GFS/ECMWF
blend working well for both position and timing.
...Pacific Northwest atmospheric river leading a longwave trough
pushing into the West on Sunday...
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Preference: Blend of non 01/00Z GFS guidance
Confidence: Average
...06Z Update...
The 01/00Z non-NCEP guidance showed good run to run continuity so
no change in preferences was necessary.
...Previous Discussion...
There is reasonable agreement with the evolution of a longwave
trough across the West Coast into the Great Basin into early next
week. There 01/00Z GFS maintained continuity with its previous
run, which meant that it remained a bit quicker than then model
consensus with the leading edge of the trough by early Sunday.
Model deterministic models cluster better with the 31/12Z ECMWF
and UKMET. A non 12Z GFS blend of guidance looks reasonable for
the western U.S. trough since differences among the non-GFS
deterministic guidance are minor.
...Leading shortwave tracking through southern Canada on Sunday
with accompanying surface low...
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Preference: General model blend
Confidence: Average
...06Z Update...
No changes were made to the previous preferences based on a good
continuity and support from the ensembles...
...Previous Discussion...
Weak height falls moving eastward across southern Canada on Sunday
and Sunday night be accompanied by a weak area of low pressure at
the surface. The 01/00Z GFS remained a bit faster than the 31/12Z
ECMWF...with other guidance in reasonably close proximity. Still
think that the model differences are small enough that a general
model blend should work.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Bann