Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1258 PM EDT Mon Jul 16 2018

Valid Jul 16/1200 UTC thru Jul 20/0000 UTC

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

12Z Model Evaluation...with Final Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Overall Model Analysis for the CONUS...

Overall Preference: A general non-UKMet blend, weighted more
toward ECMWF
General Confidence: Slightly above average

The models continue to exhibit reasonable consensus with respect
to the upper level pattern through Thursday, as the broad
mid-upper level ridge that has been controlling the weather
pattern over the CONUS becomes increasingly suppressed and
confined more to the Southwest. This will foster numerous
shortwaves across the northern tier, with the evolution toward an
overall longwave trough (though with an embedded shortwave
ridging) over the eastern CONUS by the middle-latter part of the
week. As typical, the difference among the models is in the
details -- especially with regard to the timing/depth/amplitude of
the shortwaves, and particularly the one over the north-central
CONUS Wed-Thu. The 12Z NAM was again excluded from the preference
for convective feedback issues from an MCS activity over the
central Plains on Tuesday. Meanwhile, the 12Z GFS also indicates
some convective feedback with the MCV over the northern Plains Tue
night into Wed morning (closing off a 500 mb low underneath the
shortwave ridge). Overall though the NAM/GFS/ECMWF ultimately end
up with a fairly similar mass field depiction by 00Z Friday, with
by that time the NAM on the slower/western edge of the guidance
spread while the operational GFS is faster/farther east. The 00Z
UKMet meanwhile was the most de-amplified and thus progressive
model among the global guidance, especially in the mid-Atlantic
and Southeast by Thursday, and as such was not utilized in the
preferred model blend. The 00Z ECMWF solution offered a nice
middle ground from the NAM and GFS, and thus was given
considerable weight with the preferred blend toward the end of the
period (by day 3). As is typical for the summer months, a
considerable amount of the QPF uncertainty is related to the
convective nature of the rain.

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

Hurley