My thought is to put everything into GMT - so that 10am is 10am everywhere, and track the offset in a new column in my data. I believe this would work, but am having trouble completely wrapping my head around it:
Focusing on a watershed that cross from CST into EST - if it was raining at 10am EST, and also raining at 9am CST (raining at the timezone division, with weather stations on either side of the timezone division), it's raining at the same time, we are just marking the 'time' differently in each location. However, if I transformed my date/time into GMT, with a new column tracking the offset (maybe to convert it back later), it would be the same GMT time in both locations that the rain was occurring? In effect, it is just shifting all the weather into the same time zone, and then merging based on IDW.
Does anyone have any simple solutions I am overlooking?