Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
238 AM EDT Fri Jul 20 2018

Valid Jul 20/0000 UTC thru Jul 23/1200 UTC

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

00Z Model Preferences and Confidence Intervals
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Convective frontal wave emerging from Southeast
and moving up the Eastern Seaboard Saturday & Sunday
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: ECMWF/Canadian/NAM/UKMET compromise
Confidence: Slightly below average

The guidance takes what is a broad convective frontal wave (with
very high precipitable water values) near Vidalia, GA presently
and moves it to the coast Friday afternoon, which spurs various
forms of convective redevelopment/gridscale feedback in the
guidance.  The 00z GFS is the quickest, but the guidance as a
whole has shifted the track for this system more westerly than
seen earlier.  The National Hurricane Center believes any tropical
cyclone development potential here is low, which is supported by
GFS and Canadian-derived simulated satellite imagery which shows a
low with a developing comma head moving up the East coast from
late Saturday onward (when north of the Gulf Stream).  A
compromise of the 00z ECMWF, 00z Canadian, 00z NAM, and 00z UKMET
is preferred with slightly below average confidence considering
the significant shifts seen in the model suite over the past
twelve hours.


System moving across the Northwest & Northern Plains
Upper trough/low dropping southward into the Southeast
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The guidance shows good agreement with these features, thus a
compromise of the 00z GFS, 00z NAM, 00z UKMET, 00z Canadian, and
00z ECMWF is preferred with above average confidence.

Roth