Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1245 AM EDT Thu Jun 07 2018

Valid Jun 07/0000 UTC thru Jun 10/1200 UTC

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

00Z Model Evaluation...with Preliminary Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Broader model analysis for the entire CONUS...

General Preference: General model blend
Overall Confidence: Average

Models show good agreement overall with respect to their mass
fields across the country. There is some small variability, but
generally not systematic enough to prefer or exclude any specific
models. Some of the greater differences appear to be convectively
driven -- particularly from the Midwest into the Mid Atlantic as
multiple shortwaves embedded in the flow around a Central US ridge
focus several rounds of thunderstorms. So while there is high
confidence in the overall pattern, uncertainty does exist for some
of the details, and therefore the forecast confidence is rated as
average. For many locations, a general model blend should account
for some of these detail differences.


...Focus Area: Midwest into the Mid Atlantic...

A more prominent difference exists in the surface pattern from the
Midwest into the Mid Atlantic, especially from Friday into
Saturday. The 00Z GFS shows a surface front further south than
most of the other global models, with the ensemble means following
their operational counterparts. The 00Z NAM is slightly further
north than the GFS, but not as far north as the other global
models (12Z runs thus far). However, models are already struggling
with the position of several large convective clusters in the
Plains and central US, and generally have their precipitation too
far north at the current time. Therefore, despite better agreement
centered around the further north scenario, the GFS, GEFS Mean,
and NAM cannot be discounted. Additionally, MCS tracks can often
end up south of model consensus during the warm season. A general
model blend here may wash out a lot of the details and magnitude
of certain weather elements (such as QPF), when the primary issue
is related to placement. Right now, the WPC preference is for a
frontal position and QPF axis that is south of the non-NCEP global
model consensus, but not as far as the GFS. This may be reasonably
approximated by the NAM, but further adjustments will likely be
made to WPC QPF and front forecasts.


...Focus Area: Pacific Northwest...

Preference: Non-GFS Blend

The 00Z GFS continues to push the trough faster into the
Northwest, with the lead shortwave and mid-upper level vorticity
maximum reaching near 110W longitude by 10.12Z (Sunday morning),
while most other models have it around 5-10 degrees longitude
further west at the same time. The preference here is for a
non-GFS blend, which has much better model support, and is a
large-scale feature that should not be predominately convectively
driven.


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

Lamers