Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1246 AM EDT Sat Mar 16 2019
Valid Mar 16/0000 UTC thru Mar 19/1200 UTC
...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...
00Z Model Evaluation Including Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: 12Z ECMWF, 12Z ECMWF Ensemble, 12Z CMC
Confidence: Slightly Above Average
The synoptic pattern over North America should be persistent over
the next few days -- this weekend into early next week -- with a
highly amplified ridge along the West Coast providing some
blocking. This amplifying ridge was downstream of a North Pacific
Jet extension, and is typical of that jet evolution. Meanwhile,
broad surface high pressure will settle over much of the CONUS.
This should yield limited to zero precipitation over most of the
US, with 0.25+ inch amounts generally restricted to south Texas
and Florida. Therefore, minor model differences should not have a
substantial impact on the precipitation forecast.
Most model variation exists with some of the northern stream
shortwaves cycling through the relatively stagnant pattern. One
such shortwave will dig into the Canadian Prairies today and the
Ohio Valley on Sunday. Models forecast a swath of light QPF in the
region. The 00Z GFS continued a trend of being further north and
wetter than other global models. With the region well removed from
any significant tropospheric moisture, the preference was to lean
toward models with lighter QPF -- in this case the 12Z ECMWF,
UKMET and CMC, and the 12Z ECMWF ensemble mean.
Another shortwave will approach the coast of British Columbia
today, and eventually round the Northern Rockies. This eventually
should support some precipitation in the central Plains by Monday
Night. The 00Z NAM and 12Z UKMET lag the trough near Wyoming in
almost a rex block, while the other models show much greater
progression. The preference is to lean toward the consensus of the
ECMWF, GFS and CMC.
Given these individual preferences, the overall preference will be
a stronger lean toward the 12Z ECMWF and 12Z ECMWF ensemble mean,
with some 12Z CMC also included. Overall, though, model
differences will not lead to significant QPF differences.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
Lamers