North Shore City
The new edition introduced the variant weather rule:
28.2 Random 3-Day Storm
Until Turn 12, re-roll a Weather die roll of 1 until something other than a 1 is rolled. On Turns 12-22, if a storm is rolled it lasts for 3 turns. After the 3-day storm ends, roll for weather normally.
When I first read it my brain parsed it as meaning that in the game there would be a single 3 day storm and no other storm turns, but as my diligent opponent has noted it says to roll for storm turns normally after the 3 day storm has occurred. Of course he is right but I wonder if that is the intent of the rule. Our 3 day storm has turned into a 4 day storm after another '1' was rolled and this seems pretty devastating for the Allies.
I noted that that seems to make the random 3 day storm rule much tougher for the Allies than the historical storm variant but he correctly noted that the random gives you no guarantees that a storm will even occur.
Aside from the intent which rule is, on average, better/worse for the Allies/Germans:
Standard rules: a 3 day storm is unlikely but the risk is spread throughout the game and can hit you right in the early game and hence be more painful for the Allies
Historical: A guaranteed 3 day storm
Random: No guarantees but if you do get a 3 day storm early in the potential turns for a 3 day storm (say turn 12 or 13) then your odds of getting a far greater number of storm turns than you would normally get through statistical variance under the normal rules is increased.
Mark has commented that your rule understanding (or rather, your opponent's) is correct.
A storm is still possible after the 3-day storm. Effectively, you are ignoring (on average) 2 storms during turns 1 - 12 (12 turns with a 1/6 chance of storm each day). Those two storms you are 'ignoring' get tacked on to the first storm you roll (hence the '3-day storm'). However, the rest of the statistical probability then remains the same.
So the game effect should be slightly pro-Allied, as they will get the same number of storms <on average>, but are guaranteed to NOT have storms during the critical initial build-up phase (turns 1 - 12).
Active Developer, N'44