Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1243 PM EDT Tue Jul 02 2019

Valid Jul 02/1200 UTC thru Jul 06/0000 UTC

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

12Z Model Evaluation...with Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: General Model Blend; lesser weight toward the 00Z
UKMET/CMC
Confidence: Average

A closed upper low across the Pacific Northwest will track
northeast into the Canadian Prairie Provinces through the next
couple of days. Mid-level impulses will round the trough axis
crossing the western tier of the CONUS into the northern Plains
and the Upper Midwest.  Ridging across the Southeast will build
across the eastern seaboard.  Late Thursday into Friday, another
piece of energy will drop into the trough axis across the Pacific
Northwest thanks in part to strong riding across the Gulf of
Alaska.  

As is typical of a summer time pattern, a lot will depend on the
timing of the mid-level energy which is hard for any model to
discern even a day in advance.  However, when looking at the mass
fields and the general pattern including mid-level vorticity, most
of the models are in fairly good agreement.  There are subtle
differences among the upper level pattern with regard to the jet
streak from Montana into Canada through Day 3.  The NAM shows a
bit flatter orientation of the upper level flow as compared to the
rest of the model guidance.  This will become more evident in the
QPF by later in the period.  The 00Z CMC mass fields seem well
clustered with the model solutions, but when viewing the QPF there
seem to be lingering mesoscale differences that can not be
ignored.  Also, UKMET does seem better aligned with the guidance,
though, again difference seem to arise with mid-level impulses and
amplification.  00Z UKMET QPF placement seems to be fairly
consistent with the other model solution, meanwhile intensity much
too high. 

Based on the above and the expectation of variability within the
mesoscale features, felt a general model blend would suffice with
the understanding that lesser weight should be placed on the 00Z
UKMET/CMC given some minor mass field differences. 

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

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