Just a refinement of my interpretation
HH being the commencement hours of the TAF, in this case HH 0200, HH+3 is 0500......
Lets also insert temperatures for the example, 28 31 33 34
So for the relative Time QNH Temp, I use a simple layout for interpolation as below-
0200 1010 28
0500 1011 31
0800 1012 33
1100 1013 34
So now in the above scenario we may simply interpolate, for eg, with an ETA of 0400 I would use a QNH of 1011 for estimated altimeter settings(or 1010 for the performance charts for my estimated RTOW BRW), and a temperature of 30 degrees.
I hope this clears some confusion
