Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
301 PM EDT Mon Oct 22 2018

Valid Oct 22/1200 UTC thru Oct 26/0000 UTC

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

12Z Model Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: Blend of 12Z ECMWF, 12Z GFS
Confidence: Average

---19Z UPDATE---
No change to the preliminary preference.

---PREVIOUS DISCUSSION---
A blend of the ECMWF and GFS is the preference today, as they
provide a forecast most consistent with ensemble means and
relatively good continuity with previous forecasts. The GFS had
previously been further east and weaker with the surface low
developing near Maine, but it has trended much closer to the ECMWF
over the past several model cycles. This was the most notable
discrepancy over the past couple days.

The 12Z NAM was largely excluded as it has exhibited a typical
bias for overdeveloping some of the waves pushing across the
country -- notably the one in the Canadian Prairies by Thursday,
and the one moving from New Mexico to the southern Plains from
Wednesday into Thursday. The 00Z UKMET was near the outer fringes
of some of the ensemble height forecast spread with the evolving
Plains trough and Western ridge, leading to much higher heights
than model consensus over the West, and the trough axis being
displaced east in the Central US. Therefore, the UKMET was also
largely excluded from the preference today. Finally, the 00Z CMC
shows very different evolution of the cyclone near Maine and a
Gulf Coast low as compared to other models, and it was generally
not included in the preference as well.

...Hurricane Willa...
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Please refer to the National Hurricane Center for the latest
information on the forecast for Hurricane Willa, as well as
discussion of model preferences and forecast reasoning.

The NHC forecast generally lies between the 12Z UKMET (on the
faster end of model guidance with the approach of the hurricane to
Mexico) and the remainder of the deterministic models -- 12Z NAM,
GFS, ECMWF and CMC.

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

Lamers