Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1217 PM EDT Sun Jun 02 2019

Valid Jun 02/1200 UTC thru Jun 06/0000 UTC

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

12Z Model Evaluation and Preliminary Preference
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...Overall Pattern Across the CONUS...
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Preference: Blend of 12Z NAM/GFS with 06Z GFS

The flow is characterized by a dominant northern jet stream and
trough - ridge - trough pattern across Canada and the northern
United States, with a nearly pinched-off trough being dragged
slowly along through the southwest U.S. and a tropical disturbance
flirting with the Mexican Gulf Coast and far south Texas.

Models are reasonably well clustered with these large scale
features, so we will concentrate on the detail differences. The
stronger flow remaining well north, removed from the low center in
CA/AZ/NM, would seem to favor as slow progression as we can find
over the Southwest and Southern Plains. This favors the NAM, GFS.
Additionally, in the northern stream flow there are several models
that produce particularly flat westerly flow through the mean
ridge position in the Canadian Prairie Provinces. Given this is
downwind of the mountain obstruction, we would expect to see
shortwaves maintain some definition / amplitude through
geostrophic adjustment, more like the 06Z GFS. Admittedly, though,
the 12Z GFS trended flatter, more like the ECMWF, and the GFS-FV3
has also favored a flatter solution. For now we would tend to lean
toward the 06Z GFS, blended with the 12Z NAM and GFS... but if the
12Z suite comes into consensus across the northern stream, we will
have to re-evaluate.

The National Hurricane Center places medium odds on tropical
cyclone formation in the western Gulf of Mexico early this week.
Regardless of cyclone formation, the tropical wave will contribute
to a plume of rich tropical moisture moving up into Texas and
adjacent OK/AR/LA by Days 2 and 3, leading to the potential for
heavy rainfall ahead of the Southwest U.S. trough.

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

Burke