Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
318 PM EDT Sat Jul 07 2018

Valid Jul 07/1200 UTC thru Jul 11/0000 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: Blend of 12Z GFS; 00Z ECMWF; 12Z NAM
                    (NAM only included through first 48 hours)
General Confidence: Average

---18Z UPDATE---

No change to the preliminary preferences or reasoning. A consensus
of the ECMWF and GFS is still preferred, with the NAM also
providing a reasonable forecast through the first 48 hours.

---PREVIOUS DISCUSSION---

Model agreement is generally very good over the first 48 hours or
so, with very little difference in the mass fields, and the
greatest uncertainty related to T.D. 3 off the East Coast.
Otherwise, a large ridge will dominate the weather pattern over
most of the CONUS. The WPC QPF forecast did prefer the 00Z ECMWF
and 12Z GFS more in the Upper Mississippi River Valley for the
position of the heavy rainfall axis, relative to the 00Z CMC and
00Z UKMET.

Beyond the first 48 hours, greater differences exist with the
trough that will be digging into the Northeast. The 00Z UKMET has
the trough axis (and upstream ridge axis) displaced further west
compared to the other models, and the 00Z CMC is much flatter with
the trough through the Mid Atlantic Region (extending the upper
level high further east than the other models). The 12Z NAM,
meanwhile, shows the the trough digging more than other models.
The preference, therefore is to trend toward a blend of the ECMWF
and GFS, which is close to the ECMWF and GEFS ensemble means.


...Tropical Depression Three off the East Coast...

Preference: 12Z GFS/NAM closest to 15Z NHC Advisory
Confidence: See NHC products for more information

The 12Z runs of the ECMWF, UKMET and CMC have slowed down TD 3 and
do not advance it to the northeast as quickly as previous
forecasts. The 12Z runs of the NAM and GFS are closest to the 15Z
NHC Advisory, and show the tropical system beginning to advance
northeast early next week. Please see the latest NHC products for
the official forecast and an evaluation of forecast confidence.


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

Lamers