Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1244 AM EDT Mon Jul 22 2019

Valid Jul 22/0000 UTC thru Jul 25/1200 UTC

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

00Z Preliminary Model Evaluation, Including Preference and
Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...Much of the CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General Model Blend
Confidence: Slightly Above Average

The overall model envelope is minimal even by day 3 with both the
temporal and spatial evolution of a cold front swinging across the
east, dropping an impressive longwave trough with it. The GFS may
be a bit on the fast edge and is quicker than its ensemble mean,
while the NAM lags the consensus a bit with its timing. However,
even these are acceptable differences at synoptic scales, and see
nothing of significant to rule out any of the global suite at this
time.


...Desert SW...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Non-NAM Blend
Confidence: Above Average

With a ridge developing across the desert SW which will funnel
some monsoonal moisture northward through the period, the NAM is
very robust with a shortwave breaking down into the center of the
ridge and then rotating westward beneath it days 1-2. This is not
echoed by any other guidance, and produces QPF that is much
greater across NM/AZ than the remaining suite. The ridge is
strong, and it seems unlikely a shortwave of this intensity could
break it down so robustly as shown by the NAM. Do expect some
higher QPF in the southwest this period, and this is reflected in
the remaining guidance, but the NAM should be used with caution
across this area.

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

Weiss