Display Screen or Portion Thereof with Transitional Graphical User Interface

FIG. 1 is the first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing my new design according to a first embodiment;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing my new design according to a second embodiment;

FIG. 6 is the second image thereof;

FIG. 7 is the third image thereof; and,

FIG. 8 is the fourth image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1 to 4 and 5 to 8 , respectively. The process or period in which one image transitions to another image forms no part of the claimed design.

The outer perimeter shown in dashed broken lines in the figures illustrates a display screen or portion thereof and forms no part of the claimed design. The dot-dash broken lines in the figures illustrate a boundary line that forms no part of the claimed design. The remaining dashed broken lines in the figures illustrate portions of the graphical user interface that form no part of the claimed design.