Display Screen or Portion Thereof with Transitional Graphical User Interface

FIG. 1 is a front view of a display screen or portion thereof with a transitional graphical user interface showing a first image of the claimed design;

FIG. 2 is a front view of a second image thereof;

FIG. 3 is a front view of a third image thereof;

FIG. 4 is a front view of a fourth image thereof;

FIG. 5 is a front view of a fifth image thereof; and,

FIG. 6 is a front view of a sixth image thereof.

The appearance of the animated image sequentially transitions between the images shown in FIGS. 1 - 6 . The process or period in which one image transitions to another forms no part of the claimed design. In another embodiment, the appearance of the animated image sequentially transitions between the images shown in FIGS. 1 and 2 . In another embodiment, the appearance of the animated image sequentially transitions between the images shown in FIGS. 1 and 3 . In another embodiment, the appearance of the animated image sequentially transitions between the images shown in FIGS. 1 and 4 . In another embodiment, the appearance of the animated image sequentially transitions between the images shown in FIGS. 1 , 5 and 6 . In another embodiment, the appearance of the animated image sequentially transitions between the images shown in FIGS. 5 and 6 .

The outermost broken lines in FIGS. 1 - 6 illustrate a display screen or portion thereof and form no part of the claimed design. The remaining broken lines illustrate portions of the graphical user interface and form no part of the claimed design.