Complex sentence: Strong upper-level winds battered the storm from the northwest and sheared away Gordon's upper-level convection while polluting the storm with colder and dryer air that weakened its lower level convection.
Split into simpler sentences: Strong upper-level winds battered the storm from the northwest. They sheared away Gordon's upper-level convection while polluting the storm with colder and dryer air that weakened its lower level convection.