Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1159 PM EDT Tue Jun 26 2018

Valid Jun 27/0000 UTC thru Jun 30/1200 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

12Z model evaluation...including final preferences
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...Western U.S. to the High Plains...
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Preference: Blend of the 00Z GFS, 12Z UKMET and 12Z ECMWF
Confidence: Above average

A couple troughs will move from the West to the northern High
Plains over the next few days. In general, the guidance is in good
agreement with these systems. By the time the second, and larger,
of the two upper waves approaches the High Plains on Fri, the NAM
becomes slightly faster and a little deeper than the model
consensus. Meanwhile, the CMC by the end of the period in a little
slower than the model consensus. Thus, those two pieces of
guidance are again excluded from the preference for the time being.


...Eastern U.S...
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Preference: General model blend
Confidence: Above average

The latest guidance takes the closed low and associated upper
trough over the Midwest gradually east and toward the Mid-Atlantic
and Northeast by Thursday. The energy will begin to lift out on
Friday as a strengthening upper level ridge begins to set up over
the OH/TN Valleys and the Gulf Coast states. Models handle this
feature similarly through Thursday. After that time some
relatively minor timing/amplitude differences emerge, but with no
clear outliers. Thus, a general model blend remains the preference
at this time.


...Possible low pressure offshore the East Coast by Wednesday...
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Preference: GFS/ECMWF blend
Confidence: Average

The guidance has come around to the idea of at least a weak area
of low pressure developing near southeast NC early on Wednesday
which will then lift northeast and out to sea ahead of the
aforementioned trough moving toward the Eastern U.S. There is
rather minimal spread with the low pressure details at this time,
so a general model blend will be preferred.


Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

Orrison