Display screen or portion thereof with transitional graphical user interface

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

FIG. 2 is a front view showing a second image of the first embodiment;

FIG. 3 is a front view of a second embodiment of the claimed design;

FIG. 4 is a front view showing a second image of the second embodiment;

FIG. 5 is a front view showing a third image of the second embodiment;

FIG. 6 is a front view of a third embodiment of the claimed design;

FIG. 7 is a front view showing a second image of the third embodiment;

FIG. 8 is a front view of a fourth embodiment of the claimed design;

FIG. 9 is a front view showing a second image of the fourth embodiment;

FIG. 10 is a front view showing a third image of the fourth embodiment;

FIG. 11 is a front view of a fifth embodiment of the claimed design;

FIG. 12 is a front view showing a second image of the fifth embodiment;

FIG. 13 is a front view of a sixth embodiment of the claimed design;

FIG. 14 is a front view showing a second image of the sixth embodiment;

FIG. 15 is a front view showing a third image of the sixth embodiment;

FIG. 16 is a front view of a seventh embodiment of the claimed design;

FIG. 17 is a front view showing a second image of the seventh embodiment;

FIG. 18 is a front view of an eighth embodiment of the claimed design;

FIG. 19 is a front view showing a second image of the eighth embodiment; and,

FIG. 20 is a front view showing a third image of the eighth embodiment.

The transitional graphical user interface transitions between the figures. The appearance of the transition is sequential from FIG. 1 to FIG. 2 in the first embodiment, from FIG. 3 to FIG. 5 in the second embodiment, from FIG. 6 to FIG. 7 in the third embodiment, from FIG. 8 to FIG. 10 in the fourth embodiment, from FIG. 11 to FIG. 12 in the fifth embodiment, from FIG. 13 to FIG. 15 in the sixth embodiment, from FIG. 16 to FIG. 17 in the seventh embodiment, and from FIG. 18 to FIG. 20 in the eighth embodiment. The process or period in which an image transitions to another image forms no part of the claimed design.

The longer-length broken-line showing of a display screen and the intermediate-length broken-line showing of a display screen boundary, are included for the purpose of illustrating environmental structure and form no part of the claimed design. The remaining broken lines show elements of the graphical user interface that form no part of the claimed design.