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Model Diagnostics Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1834Z Jan 24, 2020)
 
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Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
145 PM EST Fri Jan 24 2020

Valid Jan 24/1200 UTC thru Jan 28/0000 UTC

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

12z Model Evaluation with Final Preferences and Forecast Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Shortwave tracking from the Pacific Northwest to the Mid MS
Valley Sun...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 00z GFS/12z ECMWF blend
Confidence: Average

Both the 12z GFS/12z NAM are close to the consensus as the short
wave energy tracks across Vancouver Island and WA this evening and
reaches the Northern Plains around 26/00z. After this time, the
12z GFS becomes slower than the consensus, dropping the short wave
energy into the Mid MS Valley by 27/12z. The 00z GFS was more
consistent with the 12z ECMWF/00z ECMWF ensemble mean timing, so
it is preferred over the 12z GFS across the Mid MS Valley during
this time.

Because of the differences in the way the 12z GFS handles the mid
level system, it was not included in the preferred model blend.
Otherwise, there is decent model agreement with the evolution of
the mid level system, and based on the outlier 12z GFS, model
confidence is average.


...Shortwave trough crossing the West Coast Sun...reaching the
Southwest Mon...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Slightly above average

The 12z NAM/GFS are close to the consensus as the short wave
crosses the Northern and Central CA coast around 27/12z. After
this time, the 12z NAM becomes faster than the consensus by the
end of the period, making it the eastern edge of the solution
envelope. The 12z GFS/12z GEFS mean and the 12z ECMWF/00z ECMWF
ensemble mean formed a tight cluster with the trough position over
eastern NM by the end of the period.

Both the 12z CMC/UKMET joined the consensus with the placement of
the evolving long wave trough over the Southwest. However, there
remains a latitudinal difference in the placement of the surface
low over north central TX. The 12z CMC/UKMET have been more
consistent with a more southerly low placement, while the 12z
ECMWF/GFS are more consistent with a more northerly placement. At
this distance, the difference can be split on the position of the
surface low, resulting in a general model blend with slightly
above average confidence.


...Closed mid level low tracking from the Mid MS Valley across
Ohio Valley Sat into the Northeast Sun...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: 12z GFS/12z ECMWF/12z UKMET blend
Confidence: Slightly above average

The 12z NAM/12z GFS are close to the consensus with the mid level
low crossing the OH Valley into the Northeast through 27/00z.
After that time, the 12z NAM becomes faster than the consensus,
reaching the Gulf of St Lawrence by the end of the period. The 12z
GFS also becomes after that the consensus, though it is in good
agreement with the 12z ECMWF/00z ECMWF ensemble mean.

At the surface, both the 12z NAM/GFS are close with the placement
of the secondary low as it crosses ME through 27/00z. Beyond that
time, there has been a slight shift to the north with the
placement of the surface low as it moves across ME in the 12z
UKMET/12z ECMWF, moving them closer to the 12z GFS. Both the 12z
NAM and 12z CMC appear to be too fast when compared to the
tightening model cluster here. With this in mind, the overall
preference did not change.

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

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