Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1253 AM EDT Sun Jun 23 2019

Valid Jun 23/0000 UTC thru Jun 26/1200 UTC

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

00Z Model Evaluation...with Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: General Model Blend; Slightly less weighting toward
the 12Z UKMET
Confidence: Average

A longwave trough crossing the Rockies with embedded mid-level
impulses will help promote convective complexes to impact portions
of the central/southern Plains into the MS Valley region through
the next 48 hours.  As the trough axis continues to pivot through
the central CONUS it will become negatively tilted resulting in a
closed surface low shifting northeast into the Great Lakes region.
A residual surface boundary draped from the aforementioned surface
low will slowly track eastward becoming quasi-stationary across TX
into the TN Valley Tuesday into Tuesday night.  This boundary will
act as a catalyst for convective development despite the lack of
large scale forcing. As the surface low continues to lift into the
Ontario, the trailing front will shift into the northeast. With
better upper level dynamics and forcing for ascent, convection
will impact portions of the OH Valley into New England Monday
through early Wednesday.  

Models are in generally good agreement with this overall pattern. 
Though it should be noted that the 12Z UKMET still seems to
struggle with the upper/mid-level trough axis as it pivots across
the Great Lakes region Monday night into Tuesday.  The orientation
of the trough is not a steep compared to the rest of the model
suite and as a result the mid-level vorticity is weaker.  This
difference does translate into the QPF amounts and placement a
bit, but does not present itself as a major outlier. There are
subtle difference among the model guidance with respect to weak
troughing across TX and where the surface boundaries reside. 
Generally speaking though, they are in fairly good agreement,
especially under this flow regime and for Day 3.  

Later in the period, a closed upper level low will start to drift
toward the Pacific Northwest which is well aligned among all the
model guidance with run to run consistency noted. 

Based on the above logic, it would seem a general model blend
should suffice, though the 12Z UKMET should hold slightly less
weight.  

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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