Russia Weather

[LoneRunner]

I noticed a post from Old Crow in 2023 regarding Russian weather. He indicated that Russian weather effects had been recently modified. I'm guessing Russia needed help regarding air attacks in bad weather and making Russian weather worse offset some of the impact. That's my guess. Anyway, Old Crow mentioned that weather in Russia Zone 5 was determined as follows:

• September 21 to November 30: Chance of mud 75%, frozen 15%, rain 55%.
  December: Chance of rain 40%, snow 45%, mud 45%, frozen 55%.
  December 21 to March 20: Chance of snow 80%

My questions are:
Since the percentages listed add up to more than 100%, would I be correct that, for example, on September 21 the AI rolls the dice and determines if mud occurs with a 75% chance. If mud is rolled, then the AI stops and mud is the weather. If mud is not rolled, then the AI rolls for frozen with 15% chance. If frozen is not rolled, then the AI rolls for rain with 55% chance. If rain is not rolled then the weather is clear. And the rolls are repeated every turn.

I hope that makes sense. Please let me know if I'm wrong. Also, I'm wondering what part of the map is Zone 5? I'm guessing it's in Russia but Russia probably has several zones. How can I see zones? I'd definitely be interested in the European zones. And where can I see percentage chances of weather?