To change the length of time between the two actions, you could insert the word 'just' to show that the second action followed immediately (or very closely) after the first had ended. In this case, your connecting word changes to 'when'. They had just arrived in New York when the storm hit:

Past Perfect Continuous

In our section on Past Perfect Continuous, we observed that its main focus (its Reference Point - R) is the overall duration of an ongoing action in the past, and here we can place Action 2 at a specific point of interruption that can even suggest when the action began. For example, if we say, We had been arguing for three hours when the 6 o'clock news came on, we can figure out that Action 1 (arguing) began at 3 o'clock (three hours earlier). In this case, the 6 o'clock news is an interruption, and it didn't go unnoticed by whoever is telling the story. The act of arguing may have continued, but the person telling the story was aware that the news was on. Maybe the argument stopped, and they watched the news. Either way, the Reference Point of the sentence is at the point of interruption. It's at 6 o'clock:

Future Continuous

Predicting the future is a tricky business, but most of us do it based on the information we have. This is known in English-speaking countries as an 'educated guess'. Maybe you'll look at the Weather app on your phone and say, It will be raining tomorrow; or you'll look in the mirror and think, I'll get my hair cut at the weekend. However, if you think that Action 1 might be interrupted or met by another action, you'll usually use words like 'when' or 'by the time' to connect the two actions. Here's an example:

This is an educated guess, because you can predict your future status based on past behaviour and your routine. You don't have to be a fortune-teller to figure out this tense!