Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1226 PM EDT Wed Jul 17 2019

Valid Jul 17/1200 UTC thru Jul 21/0000 UTC

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

12Z Model Evaluation Including Preference and Forecast Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of the 00Z ECMWF/ 06Z GEFS mean (Northwest)
            General model blend (rest of the CONUS)
Confidence: Below average (Northwest)
            Above average (rest of the CONUS)

The remnants of Barry and its associated tropical moisture will
linger across the mid-Atlantic and Northeast one more day before
its interaction with an approaching cold front takes the system
and sensible weather impacts offshore. In the near term, model
guidance mass fields are in good agreement with the most
difference seen in the hi-res, mesoscale guidance on placement of
heaviest rainfall.

Elsewhere, large scale ridging is expected as building heights
dominate much of the CONUS and shunts any storm tracks and energy
to the far northern tier of the country and into southern Canada.
There's relatively good agreement in the models through about Day
2 but by Day 3 there are some notable differences across the
Pacific Northwest and northern Rockies that develop.

As a closed low approaches the Pacific Northwest, pieces of that
energy become sheared out and translate eastward over the southern
Canadian Rockies. However, the 00Z CMC (and to some degree the 00Z
ECMWF) suggest some blocking will occur with a building ridge
along the western Canadian coast, which closes off an upper low
over portions of WA/ID/MT. Meanwhile, the GFS/NAM are more open
and take the energy faster toward the east. The 06Z GEFS mean
shows more similarity to the ECMWF (and CMC) solutions. With that
in mind, will continue the previous blend preference for a 00Z
ECMWF/06Z GEFS mean preference and will exclude the NAM on Day 3.
For the southern US, mass fields are in good agreement such that a
general model blend will suffice and any differences with QPF will
be on the mesoscale level dictated by isolated pulse convection.


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

Taylor