Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1145 PM EST Mon Jan 07 2019

Valid Jan 08/0000 UTC thru Jan 11/1200 UTC

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

00Z Model Evaluation...with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: 00z GFS/NAM, 12z ECMWF blend
Confidence: Slightly above average

Over the next few days, the upper level pattern across the the
CONUS will transition from troughing across the central US (with
ridging along the west/east coasts) to a deeper trough across the
northeastern US, ridging/zonal flow across the central US, and a
pair of shortwave troughs moving across the western US. One
weather system will impact the northeast US Tuesday while another
west coast system brings locally heavy rain to parts of the west
Tuesday night into Wednesday. Relatively quiet weather is expected
in between.

For the northeast US system Tuesday into Wednesday, there is
better model agreement with the early look into the 00z guidance.
A surface low is expected to develop across NY then deepen off the
coast as it lifts through Nova Scotia. The 00z GFS is in very good
agreement with the 12z ECMWF and overall model spread has
decreased in the past couple of cycles. The NAM appears to be a
tad fast still but well within the ensemble spread.

For the west coast, a strong surface low is advertised to approach
the southern B.C. coast by Wednesday. Here, model agreement is
relatively good. As that system lifts into Canada, a secondary
surface low is expected to form off the California coast by
Friday. Model spread is much higher with this system, where the
GFS is on the northern spread of the guidance, while the NAM is
much more south. Here the ECMWF solution would be a good
compromise. 

In general, with the above considerations, a blend of the
GFS/ECMWF/NAM is recommended for the WPC preference this cycle.


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

Taylor