Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1223 AM EDT Thu Jun 27 2019

Valid Jun 27/0000 UTC thru Jun 30/1200 UTC

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

12Z Model Evaluation...with Prelim Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: General model blend
Confidence: Average

Over the next few days, deterministic models are closely clustered
and generally exist well within the range of ensemble
(NAEFS+ECMWF) variability. The mass field forecasts from each
model are reasonably similar, and thus a general model blend is
preferred. There is the typical uncertainty associated with
convection during the summer months that can drive notable
differences in placement of QPF maxima. A broader model blend will
account for the range of possibilities and some of the convective
variability.

One source of greater model disagreement is with a mid-upper level
vorticity maxima and low currently over the Mid Mississippi
Valley. This is projected to gradually shift to the southwest as
an upper level ridge expands in the Plains states. Models vary on
how fast to push it to the southwest. The 00Z GFS is among the
fastest, and perhaps may be a bit too fast given the distribution
of the other models.

The 00Z GFS is also a bit slower and weaker with a trough digging
into the Northeast this weekend compared to other models.
Therefore slightly less weight on the GFS may be preferred in a
couple regions, but overall a general model blend is the
preference.


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

Lamers