Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1236 PM EDT Mon Mar 25 2019

Valid Mar 25/1200 UTC thru Mar 29/0000 UTC

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

12Z Model Evaluation With Preferences and Confidence
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...Overall Pattern Across the CONUS...
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Preference: General model blend, slight lean to 00Z ECMWF
Confidence: Slightly above average

GEFS and ECMWF ensemble spreads show that the greatest sources of
model variability at the moment are with the amplitude of two
waves by mid-week -- one off the West Coast, and the other in the
vicinity of Florida. Overall, though, model agreement is fairly
good over the next several days of the CONUS, with similar QPF.

The preference was for a general model blend overall given the
large degree of similarity between the QPF. Slightly greater
weight was applied to the 00Z ECMWF as it provides greater
consistency with the previous WPC forecast. Additionally, on the
West Coast, it has greater support from other deterministic models
(00Z UKMET and CMC) and ensemble members on the placement of QPF
in northern California. Those models tend to show a more focused
jet slightly further north, while the GFS distributes the QPF
further south along the Sierra. Nevertheless, the GFS and NAM were
included in the model blend as well, just with slightly lower
weights. There was no systematic bias that would argue for the
exclusion of any one model as an unreasonable possibility.

In the vicinity of Florida on Day 1 and 2, greater emphasis was
also placed on hi-res models, as they seem to capture the expected
precipitation enhancement on the north side of the weak surface
low and/or inverted trough better than some of the global models.


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

Lamers