Is it possible for two hurricanes to combine? Or would the frontal boundaries cause them to repel each other? If they combined, what would the weather be like?
I get this question every once in a while ... so be assured you are far from the first. Tropical systems do merge at times, but what many people wonder is: "do they become 'twice' as strong?"
The answer is ... No ... thankfully!
A well-developed tropical system requires a "favorable" surrounding environment to keep it churning. When two of these systems approach one another (within a few hundred miles of one another), storm "A" tends to disrupt the "favorable" conditions for storm "B", and visa-versa. When a "merger" does occur, typically one system is sacrificed to (or more often stated as "absorbed by") the other system.
Now, it is true that we may then see the survivor strengthen, but this post-absorption strengthening is more likely the result of a return to more "favorable" environmental conditions following the absorption process rather than an energy-gain resulting from "eating" the other storm.
There is also an interesting phenomenon referred to as the "Fujiwara Effect," where two systems may briefly "dance" with each other. My understanding is that the two systems, due to their circulations, develop a linked rotation, effectively spinning around one another. This tends to be a very brief effect, and if the storms don't go their separate ways, the merging process will usually begin. The Fujiwara is mainly a Pacific storms effect, because it requires hundreds (thousands?) and miles of open water for two large storms to "tango."
Hope this helps.
WAFB Storm Team