Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
230 AM EDT Sat Jun 29 2019

Valid Jun 29/0000 UTC thru Jul 02/1200 UTC

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

00Z Model Evaluation...with Final Confidence and Preferences
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...Overall Pattern Across the CONUS...
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Preference: General model blend, less weight 00Z NAM, 00Z UKMET
Confidence: Slightly above average

---06Z UPDATE---
No change to the preliminary preference. Models are still in
relatively good agreement, and less weight is placed on the NAM
and UKMET which have less ensemble support.

---PREVIOUS DISCUSSION---
Models remain in fairly good agreement overall through the next
few days with a relatively persistent pattern: a broad ridge over
much of the CONUS, troughs in the Northwest and Northeast, and an
upper level low drifting underneath the ridge over Texas. Model
spread is limited with forecast mass fields generally similar and
tightly clustered. The preference, therefore, is for a broad-based
model blend.

The most noteworthy differences seem to be related to the
latitudinal position of a swath of heavy rainfall in the Upper
Midwest early next week, and there is some model spread with the
amplitude of the subtropical ridges over the Southeast and
Southwest (adjacent to the upper level low over Texas). The 12Z
UKMET shows a consistent trend toward higher heights through much
of the ridge. Meanwhile, the 00Z NAM shows greater amplitude to a
trough in the lee of the Canadian Rockies and lower heights in the
Northern High Plains. These models have less ensemble support, so
they are weighted less in the model preference -- as these
variations to the overall pattern likely have an influence on the
position of QPF maxima in the Upper Midwest.


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

Lamers