Greetings,

 

I am seeing METRo pavement forecast output with very poor run-to-run
consistency for locations under the following conditions:

-          There are no observations being fed back into the pavement
model

-          The atmospheric forecast (air temperature, cloud cover,
precipitation, etc.) is very consistent

 

In other words, despite a consistent atmospheric forecast and no
observations to steer the forecast otherwise, METRo pavement forecasts
vary by as much as 20 degrees over a 12 hour run-to-run period.  



Attached is a recent example of this behavior from forecasts generated
on September 8th, 2010 for a location that does not report observations.
The 'pave chart' tab shows the run-to-run pavement forecast output for
the 00z, 03z, 06z, 09z and 12z METRo model runs.  The 'pavement' tab
shows the raw data in tabular form.  In the table, I've highlighted the
12z Valid Date and Time to really highlight how the forecast changed
throughout the night despite the fact that there are no observations for
this location and despite the fact that the atmospheric forecast (air
temperature, cloud cover, precipitation amount) was very consistent over
this same time period.  

 

I assume this may be caused by the METRo model using the previous hours'
forecast as the observation and continuing from there, almost like a
self-feeding problem.  It causes forecast generated in the evening to
get progressively colder as new model runs come out and forecasts
generated in the morning to get progressively warmer as new model runs
come out.

 

Any ideas on how to resolve this?

 

Thanks,

 

Jeremy

 

Attachment: METRo run-to-run example (09.08.2010).xlsx
Description: METRo run-to-run example (09.08.2010).xlsx

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