YandaB
Newbie
I wasn't sure so I did myself a worked example (let's hope that I have it right!):OK. I see what you are getting at. But by the time your score has been de-sloped the impact on your Index will be minimal if at all.
I took the Carnoustie Championship Course, White tees. CR 75.2 and Par of 72. There are 2 holes on the back 9 (15,16) which could be a stroke higher given their length so a possible Par 74.
If we take a scratch player who happens to par all of the first 10 holes before the storm, they will then get a bogie plus 7 pars. 9 holes = 36, 10th = 4 so 40 actual shots. Add the remaining holes = 32 + 1 (for the bogie) gives an adjusted gross score of 73.
Score Differential = 113/139 x 73-75.2 = -1.8
Now pretend that the same course had added an extra shot to 15/16 to make par for the back 9 = 38. This would give an adjusted gross score of 75.
Score Differential = 113/139 x 75-75.3 = -0.2
This is a delta of 1.6 which likely changes the handicap by an extra -0.2 - as you say fairly minimal.
I also did the exercise for a 15 handicapper (as that would be 1 shot per hole CH) and that gave differentials of 13.7 and 15.3, so the same 1.6 delta.
Apologies to those for whom this is obvious, it helps me to see it all worked out
The number of times that this will happen is also pretty small so the impact overall is miniscule.