Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1245 AM EDT Fri Sep 06 2019

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

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

00Z Model Evaluation with Preferences and Forecast Confidence
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...Overall Pattern Across the CONUS...
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Preference: Non-UKMET Blend
Confidence: Average

Models are generally in good agreement with the evolution of the
synoptic pattern across the country. A trough in the eastern U.S.
will deamplify quickly as Dorian exits to the northeast, and zonal
flow will develop by this weekend to the east of the Rockies.
Meanwhile, a trough will be arriving on the West Coast this
weekend. The most significant differences are associated with this
Pacific trough. The 12Z UKMET split the associated trough into two
main segments, eventually closing off a mid-upper level low over
southern California by 09.00Z. This has no substantial ensemble
support, and has downstream effects over the Northern Plains -- by
Monday it has shortwave ridging where other models have a trough,
and its height forecast aloft generally lies outside of the
ensemble envelope. For these reasons, the UKMET is not included in
the model preference. Otherwise, model spread was rather limited
and a general blend that excludes the 12Z UKMET was preferred.


...Hurricane Dorian...
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Please refer to the official National Hurricane Center forecast
track. With the latest (03Z) NHC Advisory, there is good agreement
with the latest model suite through 48 hours as Dorian continues
northeast and begins extratropical transition, interacting with an
approaching shortwave trough from the Great Lakes region. The 00Z
NAM, and to a lesser extent the 12Z CMC, were slower and slightly
east of the NHC forecast. The other global models (12Z UKMET, 12Z
ECMWF and 00Z GFS) were reasonably close.


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

Lamers