Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1257 AM EDT Sun Sep 16 2018

Valid Sep 16/0000 UTC thru Sep 19/1200 UTC

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

00Z NAM/GFS evaluation with preliminary preferences and confidence
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...Overall preference for the lower 48...
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Preference: 00Z GFS/12Z ECMWF blend (not including Florence)
Confidence: Average

The 00Z GFS has trended toward the remaining model consensus
regarding a mid-level shortwave tracking through southern Canada
on Monday and a related surface low/cold front extending across
the Great Lakes. Minor differences exist with an trough along the
West Coast on Monday but a blend of the 00Z GFS and 12Z ECMWF fits
closest to the middle of the latest spread.

Elsewhere across the CONUS (outside of Florence described below),
the models show relatively minor differences -- which may be
largely addressed by a general model compromise.

...Tropical Storm Florence...
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Preference: 12Z ECMWF/UKMET blend closest to 03Z NHC advisory

Large scale differences between the deterministic models and the
03Z NHC advisory track for Florence begin to grow on Monday. The
00Z NAM/GFS are north/quicker with the track of Florence whereas
the 12Z ECMWF/UKMET show better agreement to each other and NHC.
The 12Z CMC splits the difference between the two camps. The 12Z
UKMET is a bit stronger with the low-mid level circulation of
Florence compared to the remaining models, however. The past 4
ensemble scatter low plots also show more support for the
NHC/ECMWF/UKMET positioning heading into Tuesday and early
Wednesday than for the NAM/GFS.

Please see NHC advisories/discussions for the latest forecast
track and thoughts concerning Florence.

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

Otto