Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1144 AM 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 NAM/GFS Evaluation with Preferences and Forecast Confidence
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...Shortwave tracking from the Pacific Northwest to the Mid MS
Valley Sun...
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Preference: 00z GFS/00z 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
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 00z 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...
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Preference: 12z GFS/00z ECMWF 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. Both the 00z CMC and 00z UKMET become slower after
27/12z. The 12z GFS/00z GEFS mean and the 00z ECMWF/00z ECMWF
ensemble mean formed a tight cluster with the trough position over
eastern NM by the end of the period.
Based on this, a blend of the 12z GFS/00z ECMWF is preferred, as
they have the support of their respective ensemble means. Given
the narrowing spread of the remaining guidance, forecast
confidence has improved to slightly above average.
...Closed mid level low tracking from the Mid MS Valley across
Ohio Valley Sat into the Northeast Sun...
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Preference: 12z GFS/00z ECMWF/00z 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 00z 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. Once again,
after that time, both models are a bit faster than the consensus,
but in the general envelope of solutions. The 00z UKMET, which has
been consistent with the secondary low, was included in the
preference with the system as well. Based on the better
clustering, the forecast confidence is slightly above average.
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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