Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1234 PM EDT Thu Mar 26 2020
Valid Mar 26/1200 UTC thru Mar 30/0000 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
12Z Initial Model Evaluation with Preferences and Confidence
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...Mid-level trough over the Southwest becoming a low as it tracks
northeast from Colorado across Central Plains and the Great Lakes
Fri night through Sun morning...
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Preference: 00Z ECMWF/ECENS/06Z GEFS Blend with some 12Z GFS on
Day 2 and 12Z NAM on Day 3
Confidence: Average
The 00Z UKMET and 00Z CMC are the first to close the low at 500 mb
on Day 2 and are thus much slower than the rest of the guidance
through Day 3. The 12Z NAM is the last to close the low, so while
it is the fastest solution on Day 2, it comes well into the fold
on Day 3. The 00Z ECMWF is right within its ensemble mean and is
the preferred model solution. The 06Z GEFS mean tracks right along
with the EMCWF/ECENS which is a little slower than the 06Z/12Z
operational GFS (which has a different model core than the GEFS).
The 12Z GFS did slow just a bit compared to the 06Z, so it is able
to be used on Day 2 (similar precip pattern to the preference),
but remains flatter/farther east with the track on Day 3.
...Shortwave and surface cold front approaching Pacific Northwest
Sat and shifting down the California coast through Sun...
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Preference: 12Z GFS/00Z ECMWF blend
Confidence: Average
There is good model agreement on the trough shifting southeast off
the Pacific Northwest before reaching the CA coast on Day 3. The
main differences are with timing and strength of the reinforcing
shortwave trough that amplifies the trough down the CA Coast. The
00Z ECMWF is the slowest/most amplified with the reinforcing
trough with the position still off the southern CA coast by the
end of Day 3 (30/00Z). The rest of the guidance is flatter, more
eastward progressive with the 12Z NAM and 00Z CMC the most and the
00Z UKMET not far behind. The QPF among the latest GFS and ECMWF
are pretty similar given their similar patterns, so they are
preferred at this time.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Jackson