Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
138 AM EST Mon Jan 06 2020
Valid Jan 06/0000 UTC thru Jan 09/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z Model Evaluation with Preferences and Confidence
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...Shortwave trough crossing the Northeast...
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Preference: General model blend
Confidence: Above average
The models are in good agreement with the shortwave advancing
through the Northeast through Monday and Tuesday, and thus a
general model blend will be preferred.
...Energy reaching the Great Lakes/Northeast Tues/Wed...
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Preference: General model blend
Confidence: Above average
The models advance the progressive shortwave trough over the
Pacific Northwest rapidly downstream over the next 24 to 36 hours
with a weak low center clipping the northern Plains and reaching
the Great Lakes by Tuesday. There will be some gradual
amplification of the system as it crosses the Great Lakes and more
so as it approaches the Northeast by Wednesday. The latest
guidance is now in sufficiently good agreement with timing and
depth that a general model blend can be preferred.
...Southern stream trough/low near the TN Valley by Tues...
...Surface low impacting the Mid-Atlantic/Northeast...
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Preference: 00Z ARW/ARW2/GEMregional blend...through 48 hrs
Non-GFS blend...after 48 hrs
Confidence: Slightly above average
The models take a shortwave trough in the southern stream and
advance it across the lower MS and TN Valleys through Monday and
Tuesday along with a gradually deepening wave of low pressure.
This system will cross the Mid-Atlantic by late Tuesday and deepen
further offshore southern New England by early Wednesday. The
guidance overall has trended a tad stronger with this system, and
have come into better timing/depth agreement with the 00Z cycle.
One notable exception is the 00Z GFS which is generally a
progressive and deeper outlier after 24 hours. The 00Z
ARW/ARW2/GEM regional solutions of the hires suite tend to favor
the non-GFS consensus at least through 48 hours. The 00Z NMMB
however appears to be a tad too suppressed with its low track. So,
a blend of the 00Z ARW/ARW2/GEM regional solutions will be
preferred through 48 hours, with a non-GFS blend after the 48 hour
time frame. A non-GFS blend may also be used in conjunction with
the aforementioned hires model suite for the early part of the
period.
...Shortwave/fronts approaching the Pacific Northwest Mon...
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Preference: Non-NAM blend
Confidence: Slightly above average
Yet another in a series of shortwave troughs and associated fronts
will arrive across the Pacific Northwest late Monday into Tuesday.
By Wednesday, this system will be traversing the Intermountain
West and there will be lee-side cyclogenesis east of the Rockies
and over the High Plains. The 00Z NAM is just a tad slower than
the model consensus as the system advances inland and traverses
the West. A non-NAM blend will be preferred given good agreement
seen out of the global models.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison