When there are two areas of low pressure near one another they fight for control.  One storm will usually strength by taking the energy from the other storm....the strong storm will take over by absorbing the weaker one...ultimately forming one large storm system.  When the transfer of energy takes place there is a zone that will end up staying mainly dry or warm enough to keep the precipitation from accumulation....called the "ripoff zone"!  It is the area that kind of get skipped over when the storms are phasing from two storms to one and is least affected by the storms...basically, these locations get ripped off!