Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
121 AM EDT Sun Jun 03 2018

Valid Jun 03/0000 UTC thru Jun 06/1200 UTC

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

00Z NAM/GFS evaluation and preliminary preferences
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Departing upper trough over the Mid-Atlantic coast today...
...Negatively titled upper trough crossing the Great Lakes today
with likely closed low over southeastern Canada Tuesday morning...
...Coastal low off of the northern Mid-Atlantic/New England coast
through Tuesday morning...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00Z NAM...00Z GFS...12Z ECMWF blend
Confidence: Average

There are detail differences with smaller scale vorticity maxima
revolving about the likely closed low which moves over
southeastern Canada early in the week, but overall there is
agreement in the latest deterministic guidance minus the faster
12Z CMC by Wednesday.

Some of the larger differences relate to a surface low tracking
offshore of the Northeast with significant northward trends
observed in the ensemble guidance compared to yesterday. However,
there is better agreement in the ensemble scatter low plots today
compared to yesterday and given the shorter forecast duration into
the future, confidence is a little higher. A combination of the
00Z NAM...00Z GFS and 12Z ECMWF are more closely tied to the
latest ensemble mean's position for the surface low compared to
the 12Z UKMET/CMC which are closer to the New England coast.


...Mid-level vorticity maximum over the Southwest U.S. today,
reaching the Plains on Monday...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00Z GFS, 12Z ECMWF, 12Z UKMET blend
Confidence: Average

The differences with this system develop as it reaches the Plains
on Monday, likely convectively generated. The ensembles show the
00Z NAM as too deep with the mid-level trough axis as it nears the
Mississippi River, while the 12Z CMC is faster than the ensemble
consensus. A blend of the 00Z GFS, 12Z ECMWF and 12Z UKMET is
recommended at this time.


...Upper level troughing over the Northwest through Tuesday...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00Z NAM/GFS blend
Confidence: Average

The greatest model differences are with shortwave energy in the
base of the mid-level trough across the Northwest on Tuesday. The
12Z ECMWF is on the stronger side and in a minority with respect
the available ensemble guidance. Comparing the mid-level heights
and surface low positions, the 00Z NAM/GFS show better agreement
to the ensemble means than the remaining models.


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

Otto