Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
332 PM EDT Sun Sep 01 2019

Valid Sep 01/1200 UTC thru Sep 05/0000 UTC

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

12Z Model Evaluation, Confidence, and Preferences
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...Overall Pattern Across the CONUS...
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Preference: General model blend of 12Z guidance
Confidence: Average

19Z Update: The 12Z CMC and 12Z UKMET trended more toward the
NCEP/ECMWF guidance with respect to the Pacific Northwest energy,
splitting off some and holding it back into Day 3. With this in
mind, a general model blend can be applied across the CONUS,
outside of the southeast U.S. (Hurricane Dorian).

---previous discussion---
The overall synoptic pattern across the CONUS is expected to
feature an active northern stream with general troughing over the
Great Lakes and Northeast U.S. while ridging aloft builds and
expands from the southwest U.S. toward the southern Plains. The
biggest model differences revolve around a piece of energy
currently offshore the Washington State coast and how it will
translate eastward over the next 3 days. In general, the non-NCEP
guidance (CMC/UKMET) do not break off any of the energy and takes
the shortwave through the northern Plains by Day 2 with more
ridging over the Pacific Northwest in its wake. Meanwhile, the
NCEP guidance plus the ECMWF suggest a closed low lingering over
the Pacific Northwest through Day 2 - 2.5, then it gets picked up
toward the northern Rockies and northern Plains by Day 3. Given
the support from the GEFS and ECENS, the preference is for the
NCEP/ECMWF guidance (non-CMC, non-UKMET) blend especially for the
northern tier US.


...Hurricane Dorian...
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Please refer to the official National Hurricane Center forecast
track

The latest GFS/UKMET/ECMWF are tightly clustered to the 15Z NHC
track through Day 3, and lies within the model spread and near the
middle of the consensus. The CMC is considerably too far west
while the NAM is on the right side of the consensus and track.

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

Taylor