Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
200 PM EST Sat Mar 07 2020
Valid Mar 07/1200 UTC thru Mar 11/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Model Evaluation with Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: General model blend;
Exception: 00Z ECMWF, 00Z UKMET, 00Z CMC along West Coast
Confidence: Slightly above average
---19Z UPDATE---
No change to the preliminary preference. The GFS and NAM continue
to appear too fast with the approach of the closed low along the
West Coast relative to the 12Z runs of the remaining guidance.
---PREVIOUS DISCUSSION---
Models are in fairly good agreement with their mass fields and the
timing and placement of precipitation over the central and eastern
United States over the next few days. The 12Z GFS and NAM may be
slightly more progressive in the eastward progression of a broad
trough from the Plains to the Appalachians on Monday and Tuesday,
but overall the differences are relatively minor.
Larger differences exist with a closed low that will develop over
the northeast Pacific this weekend, and then slowly approach the
California coast early next week. The 12Z GFS continues to be on
the faster side, with the 12Z NAM slightly less so. This is a
typical bias for the GFS, and it is not favored in this case as
strong closed lows (particularly with multiple closed 60m
isoheights) tend to progress more slowly. The GEFS mean is slower
than the deterministic GFS, as are the 00Z ECMWF, UKMET, CMC and
ECMWF Ensemble Mean. Therefore, the preference is to trend toward
these slower models along the West Coast, particularly on Monday
and Tuesday.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Lamers