Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1233 PM EDT Tue Jun 04 2019

Valid Jun 04/1200 UTC thru Jun 08/0000 UTC

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

12Z Model Evaluation with Confidence and Preference
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...Overall Pattern Across the CONUS...
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Preference: Non-NAM, non-CMC blend
Confidence: Slightly above average

Fairly flat and fast flow across the northern US with a couple
different shortwaves expected to cross through the CONUS over the
forecast period. One such trough axis expected to swing through
Thursday across the northeast US with a cold front passage.
Overall, the model agreement through 60 hours with this feature is
above average, with the faster 06z GFS now has slowed down with
its 12z run slightly. It might be still a touch faster, but
overall there is pretty good agreement.

Across the southern US, with a open mid/upper wave slowly working
through the southwest US and Texas. The NAM is too far north with
its passage likely due to a stronger jet pattern to the north. As
a result, its QPF distribution is further north than the rest of
the deterministic guidance. Additionally, the CMC has a weaker
downstream ridge, which allows the shortwave to progress faster.
This takes the tropical moisture (and weak surface low) currently
over the western Gulf further northeast (inland) faster than the
rest of the guidance. A slower, slightly stronger, solution
similar to the GFS and ECMWF (and UKMET to some degree) appears to
show better consistency to the previous forecast and lies within
the ensemble spread.

Finally, a stronger shortwave trough will work into the Pacific
Northwest toward the end of the forecast period. Here, the UKMET
is a bit stronger/more amplified though likely not different
enough to be too significant.

Overall, given the differences seen across the southern US, a
non-NAM, non-CMC blend is preferred for this cycle.


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

Taylor