Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
305 PM EDT Sat Jun 08 2019

Valid Jun 08/1200 UTC thru Jun 12/0000 UTC

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

12Z Model Evaluation...with Preliminary Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: General model blend
Confidence: Slightly above average

...19Z update...

Continued convergence in the 12Z ECMWF/UKMET/CMC was seen
regarding the northern stream trough approaching the Great Lakes.
The 12Z ECMWF/UKMET sped up slightly while the 12Z CMC slowed
down. The preference across the CONUS remains a general model
blend but differences noted, especially in the 12Z GFS near the
Great Lakes (faster) and 12Z NAM out East (stronger) remain with
less weight on these models recommended for those times/areas of
the CONUS.

...previous discussion follows...

Meridional flow continues for the short range period with an
initial quasi-rex block in place over the eastern half of North
America, followed by a progressive upper trough approaching from
the Northwest. It is with the western trough tracking eastward
across the Great Lakes where the largest differences are found,
however, overall no single model appears to differ enough from the
ensemble and remaining deterministic guidance to rule it out.
Ensemble agreement is better than yesterday but modest spread
remains for the Great Lakes system.

Overall, a general model blend is preferred across the lower 48
with each model showing similarly to the remaining guidance but
with portions of a single model's placement/strength unfavorable
for a short time...but not enough to rule it out completely.

Across the East, the 12Z NAM is on the stronger side of the
available guidance with a surface low along the Mid-Atlantic coast
Sunday night into Monday. The 12Z GFS continues to appear a bit
too fast with the shortwave, resulting in a farther north surface
low track through the Great Lakes region into southeastern Canada
Monday/Monday night but the 00Z ECMWF/UKMET could be a touch slow.
By Tuesday, the 12Z NAM ends up a bit slower with the mid-level
shortwave tracking into Quebec. Relatively minor differences
appear in a third wave, expected to reach the Great Plains on
Tuesday.

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

Otto