Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
308 AM EDT Mon Jul 27 2020
Valid Jul 27/0000 UTC thru Jul 30/1200 UTC
...See NOUS42 KWNO (ADMSDM) for the status of the upper air
ingest...
00Z Model Evaluation Including Preferences and Forecast Confidence
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07Z update: No significant changes noted in the 00Z guidance and
the model blend preferences remain.
...Mid-upper level troughing over the northern CONUS...
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Preference: General model blend
Confidence: Above average
Mid to upper-level energy over southern Canada is expected to
close off before settling over Ontario later in the period, while
the larger scale trough deepens over the Great Lakes region. At
the surface, a pronounced cold front is forecast to march across
the northern tier into the Great Lakes while upstream ridging
builds over the Canadian Rockies. In the increasingly amplified
pattern, the models have converged on a similar idea and show very
good agreement through 84 hours with the synoptic pattern.
...Mid-level energy over California/Great Basin...
...Energy advancing southeast across the Plains by Wednesday...
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Preference: General Model Blend through 60 hours; ECMWF/GFS blend
after
Confidence: Average
A piece of mid-level energy over southern/south-central California
lifts through the Great Basin over the next couple of days. As it
reaches the Rockies and into the Front Range, it amplifies as
heights build upstream and troughing settles over the Great Lakes.
The NAM is the fastest to eject the energy into the Central Plains
while the CMC bottles it up back over Wyoming through the period.
The UKMET also amplifies the ridge too much, so the model
preference is for a blend of the GFS/ECMWF, beyond 60 hours.
...Shortwave troughs approaching CA/Pacific Northwest...
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Preference: General model blend
Confidence: Above average
Models have come into slightly better agreement with the
development of a large closed low well offshore the Pacific
Northwest late in the forecast period. With the increasingly
amplified pattern characterized by ridging anchored over the Great
Basin into the Interior West, the upper level low upstream stalls
and deepens. The models have converged on a similar synoptic
pattern and no real significant issues in the mass fields were
noted. A general model blend is preferred.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
This product will terminate August 15, 2020:
www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_termination.
pdf
Taylor