Display screen or portion thereof with transitional graphical user interface

FIG. 1 is 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 the fourth image thereof;

FIG. 5 is the fifth image thereof;

FIG. 6 is the sixth image thereof;

FIG. 7 is the seventh image thereof;

FIG. 8 is the eighth image thereof;

FIG. 9 is the ninth image thereof;

FIG. 10 is the tenth image thereof;

FIG. 11 is the eleventh image thereof;

FIG. 12 is the twelfth image thereof;

FIG. 13 is the thirteenth image thereof;

FIG. 14 is the fourteenth image thereof;

FIG. 15 is the fifteenth image thereof;

FIG. 16 is the sixteenth image thereof;

FIG. 17 is the seventeenth image thereof;

FIG. 18 is 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. 19 is the second image thereof;

FIG. 20 is the third image thereof;

FIG. 21 is the fourth image thereof;

FIG. 22 is the fifth image thereof;

FIG. 23 is the sixth image thereof;

FIG. 24 is the seventh image thereof;

FIG. 25 is the eighth image thereof;

FIG. 26 is the ninth image thereof;

FIG. 27 is the tenth image thereof;

FIG. 28 is the eleventh image thereof;

FIG. 29 is the twelfth image thereof;

FIG. 30 is the thirteenth image thereof;

FIG. 31 is the fourteenth image thereof;

FIG. 32 is the fifteenth image thereof;

FIG. 33 is the sixteenth image thereof; and,

FIG. 34 is the seventeenth image thereof.

The outermost broken lines show the display screen or portion thereof and form no part of the claimed design.

The remaining broken lines in the figures depict portions of the transitional graphical user interface which form no part of the claimed design.

The appearance of the transitional graphical user interface sequentially transitions between the images shown in FIGS. 1-17 and in FIGS. 18-34 , respectively. The process or period in which one image transitions to another forms no part of the claimed design.