Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
245 AM EDT Wed Jun 12 2019

Valid Jun 12/0000 UTC thru Jun 15/1200 UTC

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

00Z Model Evaluation...with Confidence and Preferences
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...Great Lakes/Ohio Valley/East Coast...
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Preference: Non-CMC blend
Confidence: Average

Shortwave energy digging southeast across the Midwest is expected
to amplify over the next couple of days which will result in a
deep trough and associated closed low that cross the Great Lakes
region, OH Valley, and the Northeast. Model spread is relatively
small concerning the depth and timing of the energy evolution, but
the 00Z NAM does tend to be stronger than the global model
consensus as the height falls pivot across the lower Great Lakes
and interior of the Northeast. Conversely, the 00Z CMC is on the
weaker side of the model suite. The remaining guidance is
clustered in between, but there is some ensemble support,
especially from the 18Z/00Z GEFS suites for a somewhat stronger
solution similar to that of the NAM.

At the surface, all of the models strongly support a wave of low
pressure developing over the Midwest which moves through the OH
Valley Wednesday, the lower Great Lakes region on Thursday, and
then up into southeast Canada on Friday. Meanwhile, as this is
occurring, there will be a separate wave of low pressure
developing over the coastal plain of the Southeast which will
quickly lift north-northeast along or just inland of the East
Coast through Thursday before gradually getting absorbed by the
Great Lakes trough/closed low. There is some mass field spread
seen with the East Coast low track, as the 00Z CMC is farthest to
the east with the track (generally right along the East Coast) and
also gradually the fastest solution. All of the models outside of
the CMC take the low a tad farther west and inland of the East
Coast through the period. The 00Z HREF guidance led by the
NAM-conest, ARW/ARW2 and NMMB all support this as well, although
they are a bit weaker than the global models regarding their
surface wave intensity. Only the NAM-conest tends to have the
strength that the global models exhibit. Based on all of this, a
non-CMC blend will be preferred, with strong weight toward a blend
of the NAM, GFS, UKMET and ECMWF.


...Western and Southern U.S...
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Preference: Non-NAM blend
Confidence: Slightly above average

Elsewhere across the CONUS (western and southern U.S.), model
agreement is slightly above average with better confidence in the
mass fields. Mid to upper-level ridging along the West Coast will
gradually break down as a mid-level shortwave comes onshore. As
this wave advances inland across the Great Basin, the guidance
overall is rather well clustered, but the 00Z NAM does exhibit a
tendency to be a tad stronger than the global models. Also,
farther downstream across the southern Plains, lower MS Valley and
TN Valley, the 00Z NAM is a bit of a stronger outlier with a
leading shortwave impulse. Based on this, a non-NAM blend will be
preferred across the western and southern U.S. at this time.


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

Orrison