Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1125 PM EST Mon Jan 06 2020
Valid Jan 07/0000 UTC thru Jan 10/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z Model Evaluation with Preferences and Confidence
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...Southern stream trough/low over the TN Valley...
...Surface low impacting the Mid-Atlantic/Northeast on Tues...
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Preference: General model blend
Confidence: Above average
A compact, progressive shortwave trough currently advancing toward
the TN Valley will be gradually amplifying on Tuesday as it
crosses the Mid-Atlantic region. This will allow an attendant wave
of low pressure to deepen as it crosses from the TN Valley to the
lower Chesapeake Bay/VA Tidewater region by Tuesday evening. The
system will then quickly exit out to sea southeast of New England
through early Wednesday. Overall, the models are in very good
agreement with the system, with very modest differences with
respect to timing/depth, and so a general model blend will be
preferred.
...Northern stream trough crossing the Northeast by Wed...
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Preference: General model blend
Confidence: Above average
The models advance a northern stream upper trough and attendant
cold front across the Great Lakes on Tuesday, and then through the
Northeast on Wednesday. Very good model agreement is seen with
this on the large scale, so a general model blend will be
preferred with this energy as well.
...Parade of shortwaves crossing the Pacific Northwest...
...Energy advancing east across the Plains/Midwest...
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Preference: Non-NAM blend
Confidence: Slightly above average
By late Tuesday and into Wednesday, there will be another
shortwave trough and front crossing the coast of the Pacific
Northwest. On the large scale sense, the timing/strength appears
very agreeable between the various deterministic models. As this
system traverses the Intermountain West and then the High Plains
by early Thursday, there will be another shortwave crossing the
Pacific Northwest that will then dive southeast toward the Four
Corners region late Thursday and Friday. There is a bit more
spread seen in the guidance with this latter system, as the 00Z
NAM appears a tad too progressive and the 12Z CMC being likely a
little too deep/sharp with the trough. Farther north, the initial
system will drive cyclogenesis out across the northern Plains
which will cross the Upper Midwest and Great Lakes. The NAM
appears to be too far north with its low track, with the 12Z UKMET
perhaps a tad too slow and the 00Z GFS a little too fast. Overall,
the NAM is generally the solution that is more out of phase with
the model consensus, so a non-NAM blend will be preferred with the
succession of shortwaves advancing through the Pacific Northwest
and ejecting downstream toward the Plains and Midwest.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Orrison