Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
302 AM EDT Mon May 27 2019

Valid May 27/0000 UTC thru May 30/1200 UTC

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

00Z Model Evaluation Including Preferences and Forecast
Confidence...
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...Overall CONUS Overview...
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Preference: Through 29.00z - General model blend
            After 29.00z - ECMWF/GFS blend
Confidence: Average

07z update: No significant changes needed to the model blend
preference with the rest of the 00z guidance now available.

---previous discussion---
Amplified and active weather pattern will continue to evolve over
the CONUS through the next 3 days. The anomalous closed low over
southern California will push out into the central Plains by
Tuesday while the strong subtropical ridge over the southeast US
is slowly shunted south. By Thursday morning, the closed low will
open up over the mid-MS River Valley while another piece of
northern stream energy skirts the northern Great Lakes.

Through 48 hours /29.00z/ the latest deterministic guidance is
really good agreement with the large scale mass fields, showing
the closed low over California moving to the front range of
Colorado. Both spatially and magnitude are similar with the new
00z guidance in relation to the previous trends. Day 3 exhibits
the largest model differences, as the open wave becomes absorbed
with the northern stream energy as well as works against the
ridging over the southeast US. How fast this happens or progresses
is the main question, with the NAM and UKMET on the end of the
model guidance. Meanwhile, the GFS is slowest, keeping the
shortwave closed back over Nebraska. The CMC and ECMWF are more of
a middle approach.

A general model blend can be applied for the first 48 hours
/29.00z/ then the preference is for a GFS/ECMWF blend, given the
trends with the closed low opening up over the Midwest and the
strength of the downstream ridge.


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

Taylor