Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1207 AM EST Sat Feb 02 2019

Valid Feb 02/0000 UTC thru Feb 05/1200 UTC

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

00Z NAM/GFS Evaluation...with Preliminary Preferences and
Confidence
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...Overall Pattern across the CONUS...
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Preference: 00Z NAM/GFS blend
Confidence: Average

The upper pattern across the lower 48 through Tuesday will remain
active across the West Coast with a series of mid-upper level
waves to cross the region. Two surface lows will track through the
upper Midwest, with the second and stronger low affecting the
northern Plains to Great Lakes Sunday night into Monday. Across
the Southeast, cyclogenesis will occur along a coastal boundary on
Sunday but should track far enough offshore to only have minor
impacts for the coastal Carolinas.

Across the West with the West with the closed low, minor timing
differences show up with the newer 00Z NAM/GFS preferred over the
slightly slower 12Z ECMWF/UKMET/CMC given better initialization of
the upper low position. Differences across the West with this
system are relatively minor at this point given landfall within
the next 24 hours.

A weak surface low tracking across the upper Mississippi Valley
Sunday shows good agreement in the models outside of the 12Z UKMET
which does not match the 500 mb vorticity max consensus or surface
low consensus shown by the remaining models. A second and more
significant surface low for Sunday night/Monday morning shows
timing differences between the models with the 00Z NAM fastest,
followed by the 00Z GFS, the 12Z ECMWF/UKMET were slower but the
12Z CMC was slowest. The 00Z GFS blended with the faster 00Z NAM
appeared best here given the GFS/NAM show better initialization
with the ongoing closed low in the eastern Pacific and trends in
the ensemble scatter low plots have been generally been quicker
despite relatively good agreement.

Generally good agreement was observed in the latest deterministic
guidance with a weaker shortwave nearing the California coast late
Sunday night between the 00Z NAM, 00Z GFS and 12Z ECMWF but the
12Z UKMET/CMC were slower. However, The next closed low to set up
near the Pacific Northwest Coast for Monday shows no significant
differences between the latest available models.

Off of the Southeast coast, individual cycles show minor
differences, with the favored ensemble mean surface low positions
best represented by a 00Z NAM, 00Z GFS and 12Z ECMWF blend.

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

Otto