Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1236 AM EDT Tue Sep 17 2019

Valid Sep 17/0000 UTC thru Sep 20/1200 UTC

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

00Z Guidance Evaluation with Preferences and Forecast Confidence
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...Full latitude Western trough over the west and reinforcing
trough Thu...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General Model Blend
Confidence: Above average

Initial troughing over the west coast will lift northeast into the
northern Rockies and northern Plains through Day 1 and then is
reinforced by a secondary closed mid-level wave currently over the
Gulf of Alaska and drop it toward Vancouver Island. Overall, model
consensus has come into better agreement the past few cycles such
that a general model blend can be applied.


...Gulf of Mexico Tropical Wave...
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Preference: 18Z GEFS, 12Z ECMWF, 00Z UKMET
Confidence: Average through 19/00z, Below Average after that time

There is fairly good consensus in the weak tropical wave pushing
onshore the Texas gulf coast in the next day or so and then the
mid-level wave associated with it becoming gradually absorbed into
the troughing over the western US. The synoptic pattern is fairly
tightly clustered through 84 hours; the biggest differences lie
more in the mesoscale features that are a bit more problematic to
diagnose at this scale. For QPF, the operational GFS was much
lower compared to much of the other guidance but also
significantly lower than the most of the GEFS members. The ECMWF
and UKMET offered much higher amounts. For this cycle, a blend of
the 18Z GEFS, 12Z ECMWF, and 00Z UKMET is preferred.


...Hurricane Humberto...
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Preference: Official NHC Forecast
Best Proxy: Non-UKMET through 24 hours; GFS/ECMWF after 24 hours
Confidence: Slight Below Average

The NAM and UKMET continue to be too fast compared with the
official NHC forecast, particularly after 24 hours. The
GFS/ECMWF/CMC are fairly good proxies through 36-48 hours, then
the CMC becomes too slow and to the right of the latest track. The
00Z GFS and 12Z ECMWF at this time offer the best continuous proxy
for the next 3 days, though forecast confidence drops off
considerably after 48-60 hours across the board.


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

Taylor