Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1230 AM EDT Mon Jul 08 2019

Valid Jul 08/0000 UTC thru Jul 11/1200 UTC

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

00Z Model Evaluation Including Preference and Forecast Confidence
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...Overall Pattern Across the CONUS...
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Preference: General model blend except non-NAM day 2/3 northern
tier U.S.
Confidence: Slightly above average

Fairly typical summertime pattern expected over the next 3 days
across the CONUS with a relatively active northern stream along
the US/Canadian border while weakness in the ridge and a residual
surface low meanders down into the Gulf. Building heights are
expected by the end of the forecast period across the southwest /
Four Corners region while the Pacific Northwest sees another
shortwave by Thursday.

Overall, the latest guidance is in decent agreement with the large
scale setup and features. The two areas of concern where model
differences were observed are across the northern tier of the US
with respect to the stronger shortwave energy coming out into the
Dakotas on Wednesday. The NAM again remains too strong with its
500 mb heights, closing off while the rest of the guidance remains
neutral and open. As expected, the NAM surface low evolution is
too strong and too far to the northwest compared to the rest of
the deterministic and ensemble guidance. So for now, the NAM on
Day 2/3 was discarded in this region of the CONUS.

Elsewhere, a general model blend can be applied for the mass
fields. How a weak remnant trough over the southeast US evolves in
the coming days remains uncertain but most of the guidance takes
the low toward the central Gulf Coast by Day 3 (with the bigger
uncertainty in the medium range...). So for now, will lean on the
consensus approach given the relatively good agreement in the 500
mb heights and surface fields.


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

Taylor