Display Screen or Portion Thereof with Transitional Graphical User Interface

FIG. 1 is a front view of the first image in a sequence for a display screen or portion thereof with transitional graphical user interface, showing our new design;

FIG. 2 is a second image thereof;

FIG. 3 is a third image thereof;

FIG. 4 is a fourth image thereof; and,

FIG. 5 is a fifth image thereof.

The appearance of the transitional images sequentially transition between the images shown in FIGS. 1 through 5 .

The subject matter of this patent includes a process or period in which an image changes into another image. This process or period forms no part of the claimed design.

The outer perimeter broken lines in the drawings represent a display screen or portion thereof and form no part of the claimed design. The remaining broken lines in the drawings illustrate portions of an animated graphical user interface that form no part of the claimed design.