Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
236 PM EDT Wed Jun 27 2018

Valid Jun 27/1200 UTC thru Jul 01/0000 UTC

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

12Z model evaluation...including final preferences and confidence
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...Western US to the High Plains...
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Preference: 12Z GFS/12Z ECMWF blend
Confidence: Above average

The 12Z NAM ends up being a bit faster/deeper with the strongest
short wave that tracks from ID into ND between Fri afternoon and
Sat afternoon, which results a surface front being a bit faster
over the Northern Plains by Sat evening. The 12Z GFS is more in
line with the 12Z ECMWF and their respective ensemble means with
the mid level and surface systems. Because of the agreement, this
blend is preferred.


...Eastern US...
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Preference: General model blend
Confidence: Above average

Both the 12Z NAM and 12Z GFS were close to the consensus with the
timing of the frontal boundary crossing the Northeast and Mid
Atlantic through Thu afternoon, as well as the evolution of the
mid level ridging that builds from the Ohio Valley into the Mid
Atlantic through the period. There is some spread in the placement
of the mid level ridge by Sat evening, with the 12Z CMC
representing the western edge of the forecast envelope with
respect to the building mid level ridge.


...Possible low pressure offshore the East Coast by Wed/Thu...
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Preference: General model blend
Confidence: Above average

The 12Z NAM and the 12Z GFS were not quite as bullish with the
development of low pressure off the NC coast this afternoon and
this evening, before it heads northeast late tonight and Thu.
These solutions are close to the general model consensus
(including the non-NCEP 12Z solutions), so a general model blend
is still preferred.


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

Hayes