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 according to a first embodiment;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 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 according to a second embodiment;

FIG. 5 is the second image thereof;

FIG. 6 is the third image thereof;

FIG. 7 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 according to a third embodiment;

FIG. 8 is the second image thereof;

FIG. 9 is the third image thereof;

FIG. 10 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 according to a fourth embodiment;

FIG. 11 is the second image thereof;

FIG. 12 is the third image thereof;

FIG. 13 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 according to a fifth embodiment;

FIG. 14 is the second image thereof;

FIG. 15 is the third image thereof;

FIG. 16 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 according to a sixth embodiment;

FIG. 17 is the second image thereof;

FIG. 18 is the third image thereof;

FIG. 19 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 according to a seventh embodiment;

FIG. 20 is the second image thereof;

FIG. 21 is the third image thereof;

FIG. 22 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 according to an eighth embodiment;

FIG. 23 is the second image thereof;

FIG. 24 is the third image thereof;

FIG. 25 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 according to a ninth embodiment;

FIG. 26 is the second image thereof;

FIG. 27 is the third image thereof;

FIG. 28 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 according to a tenth embodiment;

FIG. 29 is the second image thereof; and,

FIG. 30 is the third image thereof.

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

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-3, 4-6, 7-9, 10-12, 13-15, 16-18, 19-21, 22-24, 25-27 , and 28 - 30 , respectively. The process or period in which one image transitions to another image forms no part of the claimed design.