Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1159 PM EDT Wed Jun 20 2018

Valid Jun 21/0000 UTC thru Jun 24/1200 UTC

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

00Z model evaluation...including preferences and confidence
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...Upper low crossing the mid MS/OH Valleys...
...Deamplifying over the Great Lakes by Sat...
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Preference: Non-NAM blend
Confidence: Above average

The 00Z NAM tends to hang on to a somewhat stronger reflection of
this system through the period as compared to the well clustered
global models. A non-NAM blend will be preferred.


...Series of upper troughs crossing the Northwest through Friday...
...Energy ejecting out across the Plains/Midwest...
...Closed low development over the Intermountain West by Sunday...
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Preference: Blend of the 00Z GFS and 12Z ECMWF
Confidence: Slightly above average

The models are in rather good agreement with the first trough that
crosses the Northwest and then advances downstream across the
Plains and Midwest through Saturday and Sunday, although the 12Z
UKMET gradually becomes a little flat with the energy as it
crosses the Midwest. A second trough will arrive across the
Northwest by Saturday and amplify into a closed low which drops
down across the Intermountain West by Sunday. By the end of the
period, the 12Z CMC is likely a little slow with its closed low
evolution, whereas the 00Z NAM looks like it may be a little too
deep and especially with its height falls spilling out across the
Plains. The 00Z GFS and 12Z ECMWF overall show great clustering
and best approximate the model consensus, and so a blend of these
solutions will be preferred with both systems.


...Upper trough over the Northeast on Thursday...
...Next upper trough arriving by Sunday...
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Preference: General model blend...initial trough on Thursday
            Non-NAM blend...second trough arriving by Sunday
Confidence: Above average

The models are in good agreement with the upper trough over the
Northeast on Thursday which then begins to lift out. The next
upper trough begins to arrive from Canada on Sunday. The 00Z NAM
is a little faster than the model consensus and is a bit deeper
than the global models with this second trough. A general model
blend will be preferred with the initial trough followed by a
non-NAM blend with the second trough.


...Weakening low center/MCV over the lower Rio Grande Valley...
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Preference: General model blend
Confidence: Slightly above average

The models are in very good agreement with the details of this
weakening system.


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

Orrison