Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1213 AM EDT Wed Apr 10 2019

Valid Apr 10/0000 UTC thru Apr 13/1200 UTC

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

00z Model Evaluation with Preferences and Confidence
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...Amplifying through Intermountain West by Wed spurring deep
Plains cyclone, Wed into Thurs...
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Preference: Non-NAM blend
Confidence: Above average

00z NAM showed some signs of slowing, but still resolves a strong
shortwave in Southern Canada that leads to the NAM shifting north
after 12/00z and more importantly shifting the deformation zone
and QPF axis much further northwest...enough so to suggest its
removal from the blend.  Otherwise, the guidance (particularly in
mass fields) and a bit less so in the QPF are remarkably strong to
support a non-NAM blend at above average confidence.  There is
some minor agreement/convective differences toward the end of Day
3 for the trailing/stalled frontal zone in the Lower MS, an
appears to be driven more in the mesoscale and small scale
moisture intersections.


...Pair of Northern Pacific Shortwaves, amplify larger scale
Southwest Trof Fri/Sat...
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Preference: General model(w/low NAM weight) or Non-NAM blend
Confidence: Slightly above average

Models appear to be coming into strong congruence with the three
main features initially to set up the expansion, deepening of a
broad larger scale trof through the Southwest Fri into Sat.  The
first is the strength/placement of the anticyclone in the
Southwest Prairies of Central Canada, the closed low in the Gulf
of AK currently, and the timing/strength of the Pacific jet that
shears the waves through the Pacific Northwest by Thursday.  The
mass fields suggest the 00z NAM may be a bit too fast swinging
energy through the base into the Southern Plains by Fri, leading
to a slight eastward translation and away from the growing
consensus/ensemble suite.  Otherwise, the placement of the mass
fields and frontal zones are solid enough to support a non-NAM
blend, though the NAM is not too out of place to support some low
weight inclusion, particularly through Day 2/3.  

Note: the greatest difference is related with the QPF at the end
of Day 3 across the Lower MS River, the return flow and available
moisture is strong but some guidance is more aggressive (steeper)
with frontal slope and therefore greater/more efficient with
convection...this is smaller mesoscale interaction that is always
difficult to pin-point on day 3, yet the larger scale signal is
there to have confidence toward potential QPF related hazards. 
Please refer to WPC Day 3 ERO for more details.


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

Gallina