Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
101 PM EDT Tue Jul 23 2019

Valid Jul 23/1200 UTC thru Jul 27/0000 UTC

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

12Z Model Evaluation, Including Preference and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Pacific Northwest/Far Northern Plains...
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Preference: Non-UKMET blend
Confidence: Slightly above average

A closed low will shed shortwave energy onto the Pac NW coast
Wednesday morning, before lifting E/NE across southern Canada
through day 3. The guidance is generally in very good agreement in
both intensity and timing of this feature with the exception of
the 00Z UKMET, which is a tad slower than the model consensus
after 48 hours. The remaining guidance is well clustered and thus
a non-UKMET blend will be preferred for the time being.


...Four Corners...
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Preference: General model blend
Confidence: Above average

A strong ridge of high pressure blossoming across the Four Comers
will perhaps shift ever so slightly down to the south over the
next few days in response to a series of shortwave troughs
traversing the northern tier of the nation. This ridge will allow
monsoonal moisture to wrap and around the southern and western
flanks of the high center through the period. There are some
modest difference with the placement and strength of the ridge,
but at this point, a general model blend will be preferred to
resolve these differences.


...Pacific Northwest on Friday...
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Preference: Blend of the 00Z ECMWF/ECENS mean/06Z GEFS mean
Confidence: Slightly above average

A shortwave trough is expected to pivot across the Pacific
Northwest and adjacent areas of British Columbia on Friday. The
12Z GFS is a bit faster than the model consensus, with the 00Z CMC
the slowest solution. The remaining guidance is clustered in
between. The latest GEFS mean and ECENS mean are clustered a
little slower than the operational GFS and tend to have somewhat
better support from the ECMWF. The preference will be blend of the
00Z ECMWF with the ensemble means at this time.



...Remainder of the CONUS...
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Preference: General model blend
Confidence: Above average

A general model blend remains sufficient as the global suite is in
very good agreement with the spatial and temporal evolution of a
cold front and longwave trough digging across the eastern CONUS.
Minor differences exist in where the front and any waves of low
pressure may focus along the front, but a general model blend will
suffice for now to resolve these differences.


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

Orrison