## Trying to aggregate by avg in one dimension, sum in another

Hi,
I have the following data that shows car counts by hour filtered by day of week (6, saturday). What I would like to do is coalesce this into a single average by hour for Saturday, so I can overlay live data for comparison. Because the data arrives in bursts during an hour it the measure Currentcount is by default summed, which usually serves perfectly well.

In this case I want to sum up Currentcount at the < hourly level, but average across days (ie average of 11-12 am over {today, last saturday, previous saturday......})

Generated with this:

WITH
SET [~FILTER] AS
{[Device.SiteID].[55]}
SET [~Date_Date.YWD_Week of year] AS
Exists({[Date.YWD].[Week of year].Members}, [~Date_Date.YWD_Day of week])
SET [~Date_Date.YWD_Day of week] AS
{[Date.YWD].[2017].[19].[6], [Date.YWD].[2017].[20].[6], [Date.YWD].[2017].[21].[6], [Date.YWD].[2017].[22].[6], [Date.YWD].[2017].[23].[6], [Date.YWD].[2017].[24].[6], [Date.YWD].[2017].[25].[6]}
SET [~COLUMNS] AS
Hierarchize({[~Date_Date.YWD_Week of year], [~Date_Date.YWD_Day of week]})
SET [~ROWS] AS
{[Time.HMS].[Hour].Members}
SELECT
NON EMPTY CrossJoin([~COLUMNS], {[Measures].[Currentcount]}) ON COLUMNS,
NON EMPTY [~ROWS] ON ROWS
WHERE [~FILTER]

Closest I have gotten is this:
WITH
MEMBER [Measures].[avgHourLocal2] AS
Avg(Descendants([Time.HMS].[Hour].Currentmember), [Measures].[Currentcount])
SET [~ROWS] AS
{[Time.HMS].[Hour].Members}
SELECT
NON EMPTY {[Measures].[avgHourLocal2]} ON COLUMNS,
NON EMPTY [~ROWS] ON ROWS