Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1237 PM EDT Tue Mar 26 2019

Valid Mar 26/1200 UTC thru Mar 30/0000 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
            Greatest weight to 00Z ECMWF, least to 12Z NAM
Confidence: Slightly above average

Models are in good agreement on the overall synoptic pattern and
show limited spread for most of the dominant features over the
next several days. The most model spread exists for a trough that
will evolve on Friday from a phasing of a shortwave kicking
through the West and a shortwave digging out of Canada.
Differences with that phasing play a big role in the downstream
speed of the system and timing of QPF.

The 12Z GFS generally avoids phasing the two waves leading to a
weaker, faster, and elongated low relative to the 00Z ECMWF. A
compromise of the timing and phasing extremes is preferred by Day
3 (Thursday Night and Friday), although it should be noted that a
fair number of ECMWF ensemble members show more rapid
amplification of the trough over the Midwest, likely from more
ideal phasing than even the deterministic model shows. If that
scenario unfolded, it could look more like the 00Z CMC which has a
deeper surface low developing just beyond the Day 3 period.

On Day 2, the 12Z GFS shows convective precipitation developing
further south into the warm sector over the southern Plains, and
this seems to be aligned better with the model instability axis.
There will probably be a frontal precip maximum further north, but
the GFS may show better placement of convective precipitation on
Thursday.


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

Lamers