Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
231 AM EDT Fri Aug 17 2018

Valid Aug 17/0000 UTC thru Aug 20/1200 UTC

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

00Z Model Evaluation...with Preferences and Confidence
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...Overall Synoptic Pattern across the CONUS...
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Preference: Blend of 00Z ECMWF, 00Z CMC, 00Z GFS
Confidence: Average

---06Z UPDATE---
No change to the preliminary preferences or reasoning. The 00Z
UKMET, CMC and ECMWF were fairly consistent with their prior runs.
The UKMET did trend slightly toward the consensus.

---PREVIOUS DISCUSSION---
Over the next few days, the ECMWF, CMC and GFS offer decent
agreement and all three deterministic models are contained well
within the ensemble spread envelope for their various mass fields.
Greater differences begin to emerge just beyond the time period
that is the scope of this discussion, into next week, as a surface
low begins to take shape in the Midwest. Nevertheless, in this
time period, they are close enough that a blend of the three is
preferred. The 00Z NAM shows a notably faster progression and
digging with the trough pushing into the West Coast on Sunday. It
is also out of phase with the Northeast trough as compared to the
other models. The 12Z UKMET shows better alignment with the
troughs and ridges, but its heights are notably higher east of the
Rockies by Sunday, and occasionally near the outer extent of the
ensemble spread envelope. Therefore, the NAM and UKMET were
excluded for these reasons.


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

Lamers