Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
117 AM EDT Fri Jul 06 2018

Valid Jul 06/0000 UTC thru Jul 09/1200 UTC

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

00Z NAM/GFS evaluation...with preliminary preferences
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

Preference: 12Z ECMWF
Confidence: Average

The greatest area of uncertainty is in southern Canada where a
pair of shortwaves will be crossing over Alberta and Saskatchewan
Saturday night. Run to run consistency in the guidance has been
poor and ensemble spread is large. The impacts on the U.S. relate
to a cold front in the northern Plains/upper Mississippi Valley on
Sunday with the 00Z GFS the most aggressive with the frontal
boundary pushing south. Here, a 12Z ECMWF/12Z UKMET blend was
favored.

In the western Atlantic, NHC is still monitoring the possibility
of a tropical cyclone with a 50% chance of development over the
next 5 days via the 00Z Tropical Weather Outlook. With this
system, the 12Z UKMET is strongest by Monday morning off of the
Carolinas as the system interacts with a frontal boundary, and the
00Z GFS is even closer to the coast but not as strong as the
UKMET. The 00Z ECMWF is closest to the ensemble means with
ensemble scatter low plots showing very weak support for a defined
low through Monday morning near the East Coast.

Elsewhere, there is good agreement with the remaining systems
across the lower 48 through Monday morning and given the
similarity of the mass fields, a general model blend is
recommended. The primary uncertainties will be related to
convectively influenced boundaries and how they may drive QPF in
future days of the forecast. This is typical of the summer months,
though, and the overall forecast confidence is rated as average.

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

Otto