Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1216 PM EDT Mon Mar 18 2019
Valid Mar 18/1200 UTC thru Mar 22/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation Including Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: 00z ECMWF/GFS/CMC for central/eastern US
General model blend for western US
Confidence: Above Average
The biggest model discrepancies in the forecast period are focused
on the digging shortwave trough across the Plains
Tuesday-Wednesday and then as it rounds the base of the longwave
trough over the southeast US. Across southern California and the
southwest US, a longwave trough will gradually move eastward and
likely close off over the Four Corners region.
For the Plains shortwave, the 00z UKMET is considered an outlier
with its over amplified solution and also is considerably slower
than the rest of the guidance. The 12z NAM has trended faster with
its progression, which is plausible, but also is much faster than
some of the 00z guidance, particularly the ECMWF/GFS/CMC. The
consensus at this point is for a general blend of the
ECMWF/GFS/CMC for this feature, which seems to be well within the
ensemble spread.
As the shortwave trough moves toward the east coast, the NAM spins
up a surface low off the NC coast with an axis of heavier QPF
right along the NC/SC coast. For now this is considered an
outlier, so the NAM will be not included for the central/eastern
US.
For the western US as the trough moves onshore, the NAM appears to
be in better shape spatially and temporally, and the UKMET is also
a reasonable solution. As such, a general model blend appears
sufficient.
The rest of the CONUS has relatively benign weather and for the
mass fields, the models are in pretty good agreement so a general
model blend, leaning on the ECMWF/GFS solutions, is the overall
recommendation.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Taylor