Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1232 AM EDT Sat Jun 01 2019

Valid Jun 01/0000 UTC thru Jun 04/1200 UTC

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

00Z Model Evaluation Including Preferences and Forecast Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of 00Z GFS and 12Z ECMWF
Confidence: Average

The greatest model spread over the CONUS over the next few days
remains with a trough amplifying into the Great Lakes and
Northeast on Sunday and Monday, and with the strength of a ridge
over the Southern Plains and Lower Mississippi River Valley.
Elsewhere, model spread is limited and QPFs are quite similar.
Therefore, the model preference is based primarily around how they
handle the two aforementioned features.

In the Northeast, the 00Z NAM and GFS continue to show a stronger
wave digging further south into the Northeast, while the 12Z UKMET
and ECMWF keep the core of the trough and associated upper level
low to the north of the Canadian border in Quebec. The 12Z CMC is
somewhat of an intermediate forecast. The preference would be to
lean slightly in the direction of the ECMWF in this region.
However, there is not a tremendous difference in the QPFs.
Therefore, a blend of the ECMWF and GFS with a slight lean to the
ECMWF is the preference in this region.

Over the Southern Plains, there is model variability related to
convective activity and likely mesoscale complexes that is typical
for the warm season. However, the most notable QPF difference
seems to be related to longitudinal positioning. The 00Z GFS has
the axis of precipitation on Sunday and Monday focused further
west, including into eastern New Mexico and eastern Colorado,
while the 12Z ECMWF is further east in Texas, Oklahoma and Kansas.
This seems to be related to low-mid level flow orientation and
ridge strength. The GFS and the GEFS ensemble members show a more
amplified ridge across the southern Plains (joined by the 12Z
UKMET), while the 12Z ECMWF and its ensemble members are more
suppressed. Given the position of the upstream trough axis well to
the west (near S CA and S NV), the preference is to lean closer to
the GFS in this region with some weight still given to the ECMWF.


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

Lamers