Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
406 PM EDT Sat Apr 06 2019

Valid Apr 06/1200 UTC thru Apr 10/0000 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

12Z Model Evaluation with Preferences and Confidence
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...Northern Tier of CONUS...
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Preference: Non-CMC blend
Confidence: Slightly above average

---19Z UPDATE---
The 12Z CMC has generally converged closer to the other models and
could be incorporated into a model blend. However, the preference
is still for less weight on the CMC.

---PREVIOUS DISCUSSION---
A zonal flow pattern will more-or-less persist across the northern
U.S. over the next several days, with a trough digging into the
West Coast Monday Night. Ensemble spread of various height and
temperature fields are amplified by the strong gradients
associated with the northern stream jet -- small differences in
placement lead to fairly large spread. However, the agreement on
timing and placement of major synoptic features seems reasonably
close and thus a general model blend is preferred. The one
exception is with the 00Z CMC, which has a considerably stronger
shortwave pushing through the Great Lakes on Sunday Night and
Monday, which has consequences for the flow pattern in that region
for the remainder of the period.


...Southern stream system affecting Gulf Coast...
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Preference: Non-ECMWF blend
Confidence: Average

---19Z UPDATE---
The 12Z ECMWF shows a focused band of QPF further inland over the
Southeast now, more similar to the other models. However, the
progression of the trough continues to be faster than the other
models (likely due to less amplification). The preference is still
to place less weight on the ECMWF and more weight on the GFS.

---PREVIOUS DISCUSSION---
The major difference with the southern stream trough and
associated surface low is that the 00Z ECMWF and many of its
ensemble members have a weaker trough and low. This leads to a
southward shift in QPF, less focused and located closer to the
Gulf Coast. Most other models show more substantial cyclogenesis
just inland over the Southeast, which leads to a more focused band
of QPF further inland. Given the lack of support for the ECMWF
from other models, the preference is to lean closer to the 12Z
GFS, which is supported to varying extents by the NAM, UKMET, CMC
and NAEFS.

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

Lamers